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Planning implications of a carbon dioxide-induced global warming in the Vancouver area Brooks, Kathy 1984

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PLANNING IMPLICATIONS OF A CARBON DIOXIDE-INDUCED GLOBAL WARMING IN THE VANCOUVER AREA by KATHY BROOKS B.A. The U n i v e r s i t y of B r i t i s h Columbia, 1978 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF ARTS i n THE FACULTY OF GRADUATE STUDIES (School o f Community and Regional Planning) We accept t h i s t h e s i s as conforming to the r e q u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA September 1984 © Kathy Brooks, 1984 In presenting t h i s thesis i n p a r t i a l f u l f i l m e n t of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y a v a i l a b l e for reference and study. I further agree that permission for extensive copying of t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the head of my department or by h i s or her representatives. I t i s understood that copying or p u b l i c a t i o n of t h i s t h e s i s for f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of /JmmJU/nAJAj fi &><j^Q(r\<xL P(mywnc^ The University of B r i t i s h Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3 Date Qjf, . IS JS4 DE-6 (3/81) ABSTRACT T h i s t h e s i s determines the planning i m p l i c a t i o n s i n the Vancouver area of a p o s s i b l e carbon d i o x i d e - i n d u c e d g l o b a l warming, based upon an e x t e n s i v e l i t e r a t u r e review and i n t e r v i e w s with people knowledgeable about the a c t i v i t i e s t h a t c o u l d be a f f e c t e d . P o s s i b l e s c e n a r i o s of Vancouver's c l i m a t e under g l o b a l warming c o n d i t i o n s are c r e a t e d by comparing the r e s u l t s from three d i f f e r e n t s e t s of a n a l y s e s : (1) a review of computer models of g l o b a l c l i m a t e , (2) a review of p a l e o c l i m a t i c evidence and (3) a review o f r e c e n t recorded data. These three methods each suggest Vancouver's c l i m a t e would be warmer and wetter i f the g l o b a l average s u r f a c e temper at u r e i n c r e a s e s as a r e s u l t of i n c r e a s e d atmospheric carbon d i o x i d e . Evidence suggests t h a t by 2050, annual p r e c i p i t a t i o n would i n c r e a s e by approximately 10 per cent and average annual s u r f a c e temperature would be 13°C to 15°C compared to the p r e s e n t average of 9.8°C. A warmer and wetter c l i m a t e has i m p l i c a t i o n s f o r many human a c t i v i t i e s i n the Vancouver area. T h i s t h e s i s examines the i m p l i c a t i o n s f o r (1) a g r i c u l t u r a l p r a c t i c e s , (2) f l o o d i n g c o n d i t i o n s , (3) water supply, and (4) human se t t l e m e n t p a t t e r n s (1) A g r i c u l t u r e i n the Vancouver area c o u l d b e n e f i t from i n c r e a s e d atmospheric carbon d i o x i d e because warmer temperatures would allow a wider range of c r o p s , a longer growing season and i n c r e a s e d p r o d u c t i v i t y . Wetter c o n d i t i o n s would demand l e s s i r r i g a t i o n . However, a longer growing season and i n c r e a s e d pro-d u c t i v i t y would p l a c e i n c r e a s e d demands on the s o i l and could l e a d to i n c r e a s e d pest and d i s e a s e problems. (2) The p r e s e n t annual t h r e a t of f l o o d i n g by the F r a s e r River would probably decrease because o f decreased p r e c i p i t a t i o n i n the i n t e r i o r drainage b a s i n . However, e x t e n s i v e f l o o d i n g c o u l d occur as a r e s u l t of p o l a r i c e m e l t i n g and subsequent sea l e v e l r i s e . (3) Increased p r e c i p i t a t i o n and i n c r e a s e d temperature c o u l d r e q u i r e changes to the water supply system. I f snowpack i s decreased, a d d i t i o n a l r e s e r v o i r c a p a c i t y may be r e q u i r e d . (4) Human Settlement may be a f f e c t e d by changes i n a g r i c u l t u r a l p r a c t i c e s o r water supply, but w i l l most l i k e l y be more s e v e r e l y a f f e c t e d by sea l e v e l r i s e and i n c r e a s e d r u n o f f . Many s t r a t e g i e s can be i n i t i a t e d i n response to the carbon d i o x i d e - i n d u c e d warming. Pre v e n t i n g the b u i l d - u p o f carbon i n the atmosphere seems a d i f f i c u l t and u n l i k e l y response g i v e n the problems of unknown t e c h n o l o g i e s , t i m i n g , and the need f o r i n t e r n a t i o n a l c o o p e r a t i o n . Research, m o n i t o r i n g , contingency p l a n n i n g and a d a p t i v e s t r a t e g i e s appear to be the more e f f e c t i v e f o r the immediate decades. These s t r a t e g i e s i i s u g g e s t m o n i t o r i n g c h a n g e s and r a t e o f c h a n g e , a p e r i o d i c r e -e v a l u a t i o n o f management p o l i c i e s i n l i g h t o f new i n f o r m a t i o n f r o m r e s e a r c h and m o n i t o r i n g , a p e r i o d i c r e - a s s e s s m e n t o f r e s e a r c h p r i o r i t i e s and t h e d i s s e m i n a t i o n o f i n f o r m a t i o n l i k e l y t o a i d i n t h e i m p l e m e n t a t i o n o f c o n t i n g e n c y p l a n s when t h e y become n e e d e d . I n g e n e r a l , t h e human s y s t e m s a f f e c t e d by a g l o b a l w a r m i n g need t o be made more r e s i l i e n t t o r e s p o n d t o c h a n g i n g c o n d i t i o n s . i n t h e V a n c o u v e r a r e a a t t e n t i o n s h o u l d be f o c u s s e d on t h e f o l l o w i n g i s s u e s : (1) A f u r t h e r a n a l y s i s o f t h e h a z a r d s due t o s e a l e v e l r i s e and a n a n a l y s i s o f t h e p o s s i b l e r e s p o n s e s i n c l u d i n g a d d i t i o n a l d y k e c o n s t r u c t i o n and e v a c u a t i o n and r e s e t t l e m e n t . (2) A f u r t h e r e v a l u a t i o n o f t h e i m p a c t s o n a g r i c u l t u r e . (3) F u r t h e r a n a l y s i s o f t h e e x t e n t and m a g n i t u d e o f o t h e r i m p a c t s n o t a n a l y s e d i n t h i s t h e s i s s u c h a s t h e i m p a c t s on f o r e s t r y , f i s h e r i e s , w i l d l i f e and m a j o r i n f r a s t r u c t u r e s u c h a s sewage d i s p o s a l f a c i l i t i e s . As w e l l a more d e t a i l e d a n a l y s i s o f t h e p o s i t i v e i m p a c t s i s n e c e s s a r y . A l l o f t h e s e s t r a t e g i e s r e q u i r e p u b l i c s u p p o r t i f t h e y a r e t o be i n i t i a t e d and e f f e c t i v e . A p u b l i c e d u c a t i o n p r o g r a m i s r e q u i r e d t o d e v e l o p u n d e r s t a n d i n g o f p o s s i b l e o u t c o m e s , t o b u i l d c o n c e n s u s on what s h o u l d be done and t o p r o v i d e s u p p o r t f o r a c t i o n s t h a t a r e i n i t i a t e d . A c o o r d i n a t i n g b o d y , p r e f e r a b l y t h e G r e a t e r V a n c o u v e r R e g i o n a l D i s t r i c t , i s r e q u i r e t o e n s u r e the n e c e s s a r y a c t i o n s a r e t a k e n and t o p r o v i d e l i a i s o n w i t h o t h e r government departments and a g e n c i e s t h a t would be i n v o l v e d . i v TABLE OF CONTENTS Page ABSTRACT i TABLE OF CONTENTS v LIST OF TABLES v i i i LIST OF FIGURES x ACKNOWLEDGEMENT x i Chapter 1. INTRODUCTION 1 Chapter 2. WHAT IS A CARBON DIOXIDE-INDUCED GLOBAL WARMING? 7 2.1 The Carbon Cycle 7 2.2 Human Impact i n the Carbon Cycle .... 12 2.3 Effects of Increased Atmospheric Carbon Dioxide 16 2.4 "But the Earth i s Cooling" and Other Controversies 19 2.5 Major Uncertainties 22 2.6 B e n e f i c i a l or Harmful 23 Chapter 3. DEVELOPMENT OF CLIMATIC SCENARIOS FOR VANCOUVER 25 3.1 What are Scenarios? 25 3.2 How are Scenarios Developed? 26 3.3 How can Scenarios be Used i n the Study of Global Warming 27 3.4 How are Climate Scenarios Developed?. 30 3.5 The Use of Climate Models 31 3.5.1 The Search for Suitable Models 31 3.5.2 The Atmospheres of Other Planets as Models 31 3.5.3 Computer Modelling 33 3.5.4 Results of Computer Models ... 36 3.5.5 Implications for Vancouver's Climate 4 0 3.5.6 The Present Climatic Influences i n Vancouver 41 3.5.7 Present Climatic Influences and Model Results 46 3.5.8 Net Result: A Scenario for Vancouver's Climate 48 v Page 3.6 P a l e o c l i m a t i c Evidence f o r Scenario Development 49 3.6.1 The Method Explained 49 3.6.2 L i m i t a t i o n s o f P a l e o c l i m a t i c Evidence 51 3.6.3 P a l e o c l i m a t i c Evidence from the L i t e r a t u r e 52 3.6.4 P a l e o c l i m a t i c Evidence i n the Vancouver Region 5 5 3.6.5 C l i m a t i c S c e n a r i o f o r Vancouver based on P a l e o c l i m a t i c Evidence 58 3.7 The Use o f Recent Recorded Data 59 3.7.1 The Method Explained 59 3.7.2 L i m i t a t i o n s of Recent Recorded Data 59 3.7.3 Survey of the L i t e r a t u r e 60 3.7.4 A C l i m a t i c S c e n a r i o f o r Vancouver Based on Analyses o f Recent Recorded Data .... 71 3.8 Summary of C l i m a t i c Scenarios 71 Chapter 4. IMPLICATIONS OF THE SCENARIOS 7 5 4.1 I m p l i c a t i o n s f o r A g r i c u l t u r e 75 4.1.1 I m p l i c a t i o n s f o r A g r i c u l t u r e i n General 7 6 4.1.2 The Sc e n a r i o : A g r i c u l t u r a l I m p l i c a t i o n s 8 4 4.2 I m p l i c a t i o n s f o r F l o o d i n g 90 4.2.1 ( i ) C o a s t a l Inundation 90 ( i i ) R u n o f f and F l o o d i n g 96 4.2.2 The S c e n a r i o : I m p l i c a t i o n s f o r C o a s t a l Inundation, Runoff and Fl o o d i n g 9 6 4.3 Water Supply 104 4.4 Human Settlement 106 4.4.1 Human Settlement & A g r i c u l t u r e 107 4.4.2 Human Settlement, C o a s t a l Inundation, F l o o d i n g and Runoff .. . 108 4.4.3 Human Settlement and Water Supply 10 9 v i Page 4.4.4 Human Settlement and P o l l u t i o n 109 4.4.5 Human Settlement and Fog I l l 4.5 Summary of Environmental, S o c i a l and Economic I m p l i c a t i o n s 113 Chapter 5. APPROPRIATE ACTIONS 115 5.1 What are the Choices? 115 5.2 Are There P r e v e n t i v e S t r a t e g i e s 118 5.3 What S t r a t e g i e s are Ap p r o p r i a t e f o r an Unstable Climate? 121 5.4 Can the Systems be Made More R e s i l i e n t ? 125 5.5 What I n t e r n a t i o n a l S t r a t e g i e s Can be Adopted? 127 5.6 What S t r a t e g i e s can be I n i t i a t e d i n the Vancouver area 130 5.7 C o n c l u s i o n : Where to Now? 135 BIBLIOGRAPHY 138 v i i LIST OF FIGURES Page. 1. The Greater Vancouver Regional D i s t r i c t (GVRD) .... 2 2. The Carbon C y c l e : Average Annual Fluxes 8 3. T e r r e s t r i a l Fluxes and Pools of Carbon 9 4. Monthly averages of atmospheric carbon d i o x i d e a t Mauna Loa with seasonal v a r i a t i o n removed 13 5. The e f f e c t s of atmospheric carbon d i o x i d e on incoming and outgoing r a d i a t i o n 17 6. The decrease i n mean g l o b a l temperature s i n c e 1940 an the p o s s i b l e range of f l u c t u a t i o n with or without the carbon d i o x i d e e f f e c t 20 7. The complexity of the c l i m a t i c system 3 2 8. I n t e g r a t i o n of three models - a world energy model an atmospheric temperature mode and a carbon c y c l e model 35 9. Estimates of average s u r f a c e a i r temperature change due to a d o u b l i n g o f carbon d i o x i d e i n 34 c l i m a t e models 38 10. Probable l a t i t u d i n a l v a r i a t i o n i n temperature i n c r e a s e a c c o r d i n g to c l i m a t i c models 40 11. Annual mean, maximum and minimum temperature and p r e c i p i t a t i o n i n Vancouver 4 2 12. Schematic i l l u s t r a t i o n o f the formation of cyc l o n e s and a n t i c y c l o n e s 45 13. Changes i n temperature and p r e c i p i t a t i o n as suggested by the c l i m a t e models 50 14. P r o j e c t e d l a t i t u d i n a l v a r i a t i o n i n annual s u r f a c e temperatures and annual p r e c i p i t a t i o n 56 15. An approximate d e p i c t i o n of the r e g i o n s i n the world which were wetter or d r i e r than the present d u r i n g the A l t i t h e r m a l P e r i o d about 4000-8000 years ago .. 57 16. A s c e n a r i o of p o s s i b l e s o i l moisture p a t t e r n s on a warmer e a r t h 58 v i i i Mean annual s u r f a c e temperature changes from c o l d to warm years Mean annual p r e c i p i t a t i o n changes from c o l d to warm years D i f f e r e n c e s i n s u r f a c e temperature between the mean of the 10 warmest A r c t i c w i nters and the long-term mean of the remaining winters i n the 1900-1969 p e r i o d , D i f f e r e n c e s i n s u r f a c e temperature between the mean of the 10 warmest A r c t i c summers and the long-term mean of the remaining summers i n the 1900-1969 p e r i o d D i f f e r e n c e s i n p r e c i p i t a t i o n i n North America between the mean of the 10 warmest A r c t i c winers and the long-term mean of the remaining w i n t e r s i n the 1900-1969 p e r i o d , D i f f e r e n c e s i n p r e c i p i t a t i o n i n North America between the mean of the 10 warmest A r c t i c summers and the long-term mean of the remaining summers i n the 1900-1969 p e r i o d Summary o f Scenarios The s c e n a r i o o f Vancouver's c l i m a t e with a carbon d i o x i d e - i n d u c e d g l o b a l warming , C3 and C4 P l a n t s , Annual p r o d u c t i o n of C 3 and C 4 p l a n t s by l a t i t u d e Percentage i n c r e a s e s over p l a n t s grown a t 330 ppm of carbon d i o x i d e i n r a t e o f p h o t o s y n t h e s i s , l e a f a rea, and dry weight accumulation i n f o u r p l a n t types g i v e n 12 weeks of exposure to e l e v a t e d (660 ppm) c o n c e n t r a t i o n s of carbon d i o x i d e , Rate of p h o t o s y n t h e s i s of a l f a l f a , sugarbeets, and tomatoes exposed to high c o n c e n t r a t i o n s of carbon d i o x i d e f o r 80 minutes i n f u l l sun i x Page 29. Changes i n A n t a r c t i c i c e cover with a 5° to 10°C warming 92 30. Summary of s c e n a r i o s o f f u t u r e sea l e v e l r i s e i n c e n t i m e t e r s 94 31. Areas i n Richmond, D e l t a and South Vancouver a f f e c t e d by a 5 metre r i s e i n sea l e v e l ... 99 32. Days with fog from approximately 1940 to 1978 .... 112 33. Crop y i e l d s showing p r o f i t maximizing y i e l d , and t y p i c a l s u r p l u s e s and d e f i c i t s during good and bad years 123 34. Through technology and management techniques s o c i e t y s t r i v e s t o produce the p r o f i t maximizing y i e l d and d e l e t e s u r p l u s e s and d e f i c i t s 124 x ACKNOWLEDGEMENT A t h e s i s of t h i s type which i n v o l v e s numerous d i s c i p l i n e s would not have been p o s s i b l e without the he l p o f many people. I would p a r t i c u l a r l y l i k e to thank Dr. A.H.J. Dorcey f o r being so kind and s u p p o r t i v e . Dr. Dorcey p r o v i d e s encouraging, c o n s t r u c t i v e advice and spends a g r e a t d e a l o f time with each o f h i s students and I a p p r e c i a t e t h i s v e r y much. Dr. D. Steyn o f the Department of Geography deserves s p e c i a l thanks f o r h e l p i n g t h i s " f r u s t r a t e d c l i m a t o l o g i s t . " I a l s o thank Gary S h a e f f e r o f AES f o r h e l p i n g me formulate my ideas and t a k i n g the time to read an e a r l y d r a f t . I am a l s o indebted to Sandra Smith o f the M i n i s t r y o f E n v i r o n -ment. Thanks t o the many who helped me a t the GVRD, the M i n i s t r y o f A g r i c u l t u r e and Food, the Canadian Climate Centre and the Departments of A g r i c u l t u r e and Oceanography a t UBC. And, f i n a l l y , thank you Rick f o r never doubting my a b i l i t i e s . x i CHAPTER 1 1 INTRODUCTION Accord i n g to records and analyses of i c e c o r e , t r e e r i n g and o t h e r h i s t o r i c a l evidence, the amount of carbon d i o x i d e i n the atmosphere has i n c r e a s e d over the l a s t century and i s c o n t i n u i n g to i n c r e a s e . Although there i s not complete agree-ment among s c i e n t i s t s , the growing concensus i s t h a t i n c r e a s e d l e v e l s of atmospheric carbon d i o x i d e w i l l l e a d to a g l o b a l warm-in g . The purpose of t h i s t h e s i s i s to determine the p l a n n i n g i m p l i c a t i o n s i n the Vancouver area"*" of such a g l o b a l warming. Despite c o n s i d e r a b l e u n c e r t a i n t y , the t o p i c warrants a t t e n t i o n by planners who are i n t e r e s t e d i n c o n s i d e r i n g a l t e r -n a t i v e f u t u r e s and planning so as to a v o i d i n f l i c t i n g s o c i a l and economic har d s h i p on f u t u r e g e n e r a t i o n s . A "wait and see" approach r i s k s being unable to prevent or adapt to c l i m a t i c change without e x p e r i e n c i n g c o n s i d e r a b l e adjustment and hard-s h i p . Planners have a r o l e to p l a y i n a s s u r i n g t h a t informed d e c i s i o n s are made. The s o l u t i o n to the g l o b a l warming problem i s not to be reached s o l e l y through more s c i e n t i f i c r e s e a r c h , although t h i s can reduce u n c e r t a i n t y and i d e n t i f y means of 1. For purposes of t h i s t h e s i s , the Vancouver area i s d e f i n e d as the p o l i t i c a l boundaries of the Greater Vancouver Regional D i s t r i c t (GVRD; see F i g u r e 1 ) . In some cases, the area of i n t e r e s t extends o u t s i d e the boundaries of the GVRD but i n other cases, due to l a c k of data or due to time c o n s t r a i n t s , the area of i n t e r e s t may be f u r t h e r d e f i n e d w i t h i n the GVRD. 3 reducing r i s k . Means do e x i s t to am e l i o r a t e the carbon d i o x i d e problem but most r e q u i r e s u b s t a n t i a l r esource commitment and i n t e r n a t i o n a l c o o p e r a t i o n . The ch o i c e of s t r a t e g i e s r e q u i r e s v a l u e judgements concerning the kind o f f u t u r e s o c i e t y d e s i r e s . These judgements r e q u i r e the combined e f f o r t s o f people from many d i s c i p l i n e s and, perhaps most important, an understanding of the problem by a l l members of the p u b l i c . Science has a r o l e t o p l a y i n p r o v i d i n g i n f o r m a t i o n but cannot be s o l e l y respon-s i b l e f o r the d i r e c t i o n the f u t u r e dates. In o r d e r to determine the plann i n g i m p l i c a t i o n s , the e f f e c t s of a g l o b a l warming on the climate"'" o f the Vancouver area must be determined. Researchers have used the f o l l o w i n g three methods to determine r e g i o n a l c l i m a t i c impact i n other areas: (a) numerical m o d e l l i n g o f the g l o b a l c i r c u l a t i o n system i n combination with knowledge of the present c l i m a t i c i n f l u e n c e s i n the area; (b) a n a l y s i s of p a l e o c l i m a t i c evidence of past warm era s ; (c) a n a l y s i s of the temperature and p r e c i p i t a t i o n data f o r the area to determine i f there i s a r e l a t i o n s h i p between p r e c i p i t a t i o n and temperature i n recent warm years. 1. Climate i s d e f i n e d as the average value of weather events such as temperature, p r e c i p i t a t i o n and winds observed over a p e r i o d o f time long enough to be able to d i s c e r n extreme from average occurrences (Mead & K e l l o g g , 1980). In t h i s t h e s i s , examination o f the l i t e r a t u r e r e l a t i n g to these three methods i s used to develop s c e n a r i o s o f p o s s i b l e c l i m a t e f u t u r e s f o r the Vancouver area. The s c e n a r i o s are then examined to determine the s o c i a l , environmental and economic i m p l i c a t i o n s , i . e . , What do the s c e n a r i o s imply i n terms of change f o r human se t t l e m e n t p a t t e r n s , m i g r a t i o n , a g r i c u l t u r e , water supply, f l o o d p r o t e c t i o n , p o l l u t i o n , fog, and economic a c t i v i t y ? What w i l l be the extent and magnitude of change? W i l l the change be harmful o r b e n e f i c i a l to s o c i e t y ? These ques t i o n s are f i r s t addressed at a g e n e r a l l e v e l throughout the t h e s i s and then a t a more s p e c i f i c l e v e l w i t h i n the context o f the Vancouver a r e a . F i n a l l y the p o s s i b l e responses to i d e n t i f i e d changes are examined, i . e . , What can be done i n terms of a d a p t i v e , a m e l i o r a t i v e o r p r e v e n t i v e responses to cope with the i d e n t i f i e d changes? What are the b a r r i e r s t h a t w i l l make responses d i f f i -c u l t to implement? In l i g h t o f the p o s s i b l e g l o b a l impacts, the impacts i n the Vancouver r e g i o n p a l e s i g n i f i c a n t l y . At a g l o b a l l e v e l , a carbon d i o x i d e - i n d u c e d g l o b a l warming has p o s s i b l e i m p l i c a t i o n s f o r i n t e r n a t i o n a l t r a d e , f o r world food supply and f o r migra-t i o n . Increased imbalance or d i s r u p t i o n o f these g l o b a l a c t i v i t i e s c ould l e a d to mounting i n t e r n a t i o n a l t e n s i o n , economic c o l l a p s e and p o l i t i c a l chaos, e v e n t u a l l y t h r e a t e n i n g world peace. In t h i s t h e s i s , however, the impacts are examined at the r e g i o n a l l e v e l because: 5 (a) The carbon d i o x i d e - i n d u c e d warming and i t s e f f e c t s can be an amorphous, d i f f i c u l t to understand i s s u e f o r the l a y - p e r s o n o r policymaker because the i m p l i c a t i o n s are so d i v e r s e and i n t e r r e l a t e d . By l o o k i n g a t the i s s u e a t a r e g i o n a l l e v e l a b e t t e r understanding of p o s s i b l e impacts i s achieved. (b) The g l o b a l i m p l i c a t i o n s cannot be c l e a r l y assessed u n t i l the r e g i o n a l impacts are understood. Schneider (198 2) notes t h a t i t i s p r e f e r a b l e to focus on a sm a l l number of regi o n s r a t h e r than make vague g e n e r a l g l o b a l assessments. U l t i m a t e l y , the f o c u s s i n g on r e g i o n s should allow us t o make more s p e c i f i c g l o b a l assessments. (c) The e x i s t i n g p l a n n i n g j u r i s d i c t i o n s are l o c a l i n s c a l e r a t h e r than g l o b a l . The Vancouver area was chosen because of i t s p r o x i m i t y to the r e s e a r c h e r . The f o l l o w i n g c hapter w i l l e x p l a i n what i s meant by a carbon d i o x i d e - i n d u c e d g l o b a l warming and d i s c u s s the c o n t r o v e r s y and u n c e r t a i n t i e s a s s o c i a t e d with the i s s u e . In Chapter 3, s c e n a r i o s o f the c l i m a t e o f Vancouver are developed assuming t h a t atmospheric carbon d i o x i d e w i l l continue to i n c r e a s e . These s c e n a r i o s are developed using evidence from computer m o d e l l i n g , p a l e o c l i m a t i c s t u d i e s and r e c e n t recorded data. Chapter 4 examines the s c e n a r i o s to determine the environmental, s o c i a l and economic i m p l i c a t i o n s f o r a g r i c u l t u r e , f l o o d i n g , water supply and human se t t l e m e n t . In c o n c l u s i o n , Chapter 5 examines the v a r i o u s s t r a t e g i e s t h a t s o c i e t y can take i n response to a carbon d i o x i d e -s p e c i f i c s t r a t e g i e s t h a t can be d e a l with the impacts i d e n t i f i e d induced warming and o u t l i n e s the taken i n the Vancouver area to i n Chapter 4. CHAPTER 2 WHAT IS A CARBON DIOXIDE - INDUCED GLOBAL WARMING? Chapter 2 w i l l explain what i s meant by a carbon dioxide-induced global warming by examining the carbon cycle, the impact of burning f o s s i l fuels and the role of atmospheric carbon dioxide. The controversy and uncertainties and f i n a l l y , the potential benefits or detrimental e f f e c t s of a carbon dioxide-induced warming are examined. 2.1 The Carbon Cycle There are four major global reservoirs or "pools" of carbon: the atmosphere, the oceans, the biosphere (including s o i l s ) and the sediments. The term carbon cycle indicates carbon i s mobile; exchanges or "fluxes" occur between the reservoirs through various processes. In Figure 2 the major pools and fluxes are i l l u s t r a t e d . Estimates of the quantities of carbon in each pool and the amounts exchanged annually are also i l l u s t r a t e d . By far the largest pool i s the sediments with an estimated 20,000,000 b i l l i o n metric tons of carbon. Because fluxes between sediments and other pools occur very slowly over m i l l i o n s of years, the sediments are considered v i r t u a l l y a stationary pool for most purposes. The other pools are much more active, exchanging s i g n i f i c a n t quantities of carbon annually. The cycling of carbon i s quite d i f f e r e n t on land than i n the oceans. Figure 3 i l l u s t r a t e s the t e r r e s t r i a l fluxes and Plants on Land Dead Organic Matter ^00) OCEAN Phytopiank-fon (5) .assimilation -SeaSur-fiice Layers (zo) Z o o p l a n R t o n , R s h US) Dead Organic Matter (sood) water exchange. &5> " 5 ^ 1 ' ( W O O ) 5 e d t m e n + s C l o , 0 0 o , 0 0 0 ) Coal and Oil Go,00o) FIGURE 2I T h e C a r b o n Cycle: Average Annual Fluxes. A l l quantities in b i l l i o n s of metric tons. SOURCE: Adapted from B o l i n , 1970, p. 130. i Car ho n Dioxide. FIGURE 3: SOURCE: TERRESTRIAL FLUXES AND POOLS OF CARBON. ADAPTED FROM BOLIN, 1970, P, 126, 10 p o o l s . The process begins with the a s s i m i l a t i o n o f atmospheric carbon d i o x i d e by p l a n t s through p h o t o s y n t h e s i s (35 b i l l i o n m e t r i c tons per y e a r ) . P l a n t s r e t u r n some carbon d i o x i d e to the atmosphere through r e s p i r a t i o n (10 b i l l i o n m e t r i c tons per year) but the net p r o d u c t i v i t y o f p l a n t s - p h o t o s y n t h e t i c g a i n minus r e s p i r a t o r y l o s s - r e s u l t s i n a storage o f carbon i n o r g a n i c compounds i n the le a v e s and r o o t s o f p l a n t s (450 b i l l i o n m e t r i c t o n s ) . Approximately 35 b i l l i o n m e t r i c tons of carbon i s f i x e d i n t o o r g a n i c compounds by t e r r e s t r i a l p l a n t s every year. The p l a n t s c o n t a i n i n g carbon e v e n t u a l l y become food f o r animals, i n c l u d i n g humans, or d i e and decompose. If consumed, some carbon i s l o s t through r e s p i r a t i o n by the animals; the remainder i s s t o r e d i n animal t i s s u e . When p l a n t s and animals d i e , the l i t t e r i s o x i d i z e d through a s e r i e s o f processes t h a t occur i n the s o i l . The end r e s u l t i s t h a t the carbon s t o r e d i n the t i s s u e i s r e l e a s e d to the atmosphere as carbon d i o x i d e (25 b i l l i o n m e t r i c tons a n n u a l l y ) . The amount of carbon d i o x i d e a s s i m i l a t e d by p l a n t s through p h o t o s y n t h e s i s every year roughly balances the amount of carbon d i o x i d e r e t u r n e d to the atmosphere through r e s p i r a t i o n and decomposition every year. A c t u a l l y over a p e r i o d o f m i l l i o n s o f ye a r s , a sma l l amount of carbon i n decaying p l a n t s and animals i s removed from t h i s c y c l e and i n c o r p o r a t e d i n the ea r t h ' s c r u s t as f o s s i l f u e l s o r sediments. In the ocean, the primary f i x e r s o f carbon d i o x i d e are the phytoplankton i n the near s u r f a c e waters. The phytoplankton 11 pr o v i d e food f o r zooplankton and f i s h which, i n t u r n , p r o v i d e food f o r l a r g e r animals. The f e c a l matter from these organisms and any dead organisms f a l l i n t o deeper waters where the carbon o x i d i z e s , removing f r e e oxygen and t r a n s f e r r i n g carbon to the deep oceans. The ocean depths are the second l a r g e s t p o o l of carbon (34,500 b i l l i o n m e t r i c t o n s ) . Deep l a y e r s of the ocean mix with s u r f a c e l a y e r s very s l o w l y : at l e a s t 1,000 years i s r e q u i r e d f o r the deepest waters to be completely r e p l a c e d by s u r f a c e waters. The atmosphere and the ocean s u r f a c e waters exchange carbon d i o x i d e by d i f f u s i o n . 100 b i l l i o n m e t r i c tons of atmospheric carbon d i o x i d e i s estimated to d i s s o l v e a n n u a l l y i n the near s u r f a c e waters of the ocean through wind and wave a c t i o n . Roughly the same amount of carbon d i o x i d e i s t r a n s f e r r e d from the ocean to the atmosphere each year. S i m i l a r l y to the c y c l i n g o f carbon on l a n d , a minute amount of carbon i n the ocean c y c l e i s " l o s t " every year and st o r e d i n sediments and f o s s i l f u e l s . Before the presence of humans, i t i s g e n e r a l l y b e l i e v e d the carbon c y c l e on l a n d , i n the oceans and i n the atmosphere was i n a steady s t a t e : the amount of atmospheric carbon d i o x i d e a s s i m i l a t e d by p h o t o s y n t h e s i s and by the ocean waters was equal to t h a t returned to the atmosphere by r e s p i r a t i o n of organisms or exchange by ocean waters (Pytkowicz and Small, 1977). 12 2.2 Human Impact i n the Carbon C y c l e Human impact i n the carbon c y c l e began 5,000 to 9,000 years ago with s l a s h and burn a g r i c u l t u r e , but has o n l y had a s i g n i f i c a n t impact s i n c e the I n d u s t r i a l R e v o l u t i o n (Lamb, 1977). Since about 1860, l a r g e amounts of f o s s i l f u e l s have been burned, r e l e a s i n g carbon to the atmosphere t h a t was f i x e d by ph o t o s y n t h e s i s m i l l i o n s of years ago. In 1981 an estimated 5.3 m i l l i o n m e t r i c tons of carbon were added to the atmosphere by burning of f o s s i l f u e l s ( C l a r k , e t a l . , 1982). From 1860 to the mid-1970's the use of carbon-based f u e l s i n c r e a s e d a t an expon-e n t i a l r a t e of 4.3 per cent per year (Krenz, 1978; Abelson, 1983). Many a n a l y s t s b e l i e v e t h i s r a t e i s lowering somewhat to 2.5 per cent per year ( C l a r k , 1982) which s t i l l i n d i c a t e s a do u b l i n g of prese n t consumption by the mid 21st Century. Hoffman e t a l . , (1983) conclude t h a t there i s l i t t l e i n d i c a t i o n these r a t e s w i l l drop s i g n i f i c a n t l y due to the i n c r e a s e d use of a l t e r n a t e sources. Monthly mean atmospheric carbon d i o x i d e c o n c e n t r a t i o n has been measured i n many areas of the world. The r e c o r d from the Mauna Loa weather s t a t i o n i n Hawaii i s most o f t e n quoted because of the l e n g t h and c o n s i s t e n c y o f the re c o r d s and the remoteness of the s t a t i o n from l o c a l sources of p o l l u t i o n . Figure 4 i l l u s t r a t e s the steady i n c r e a s e i n the annual mean c o n c e n t r a t i o n of atmospheric carbon d i o x i d e as evidenced a t Mauna Loa: an i n c r e a s e from 315 to 339 ppm by volume from 1958 to 1982. P r e - i n d u s t r i a l (mid 1800's) atmospheric carbon d i o x i d e 13 FIGURE 4 : M o n t h l y a v e r a g e s of a t m o s p h e r i c c a r b o n d i o x i d e at Mauna Loa w i t h s e a s o n a l v a r i a t i o n removed. S o u r c e : C o u n c i l on E n v i r o n m e n t a l Q u a l i t y , 1 9 8 1 , p . 2 . Based on d a t a f rom C D . K e e l i n g and C o - w o r k e r s , S c r i p p s I n s t i t u t i o n of Oceanography . c o n c e n t r a t i o n s are estimated to have been approximately 270 to 290 ppm (IIASA, 1983; S i e d a l and Keyes, 1983), i n d i c a t i n g a 15 to 20 per cent i n c r e a s e over approximately 100 y e a r s . E i g h t p ercent of t h i s i n c r e a s e i s estimated to have occurred s i n c e 1958 (Hoffman, e t a l . , 1983). I f the carbon d i o x i d e r e l e a s e d by burning of f o s s i l f u e l s was not removed i n any way, the amount of atmospheric carbon d i o x i d e would be expected t o i n c r e a s e . The p r e s e n t f o s s i l f u e l consumption r a t e of 5 to 6 b i l l i o n m e t r i c tons per year would be expected to i n c r e a s e the c o n c e n t r a t i o n o f carbon d i o x i d e i n the atmosphere by 2.3 p a r t s per m i l l i o n per year ( B o l i n , 1970). The measured i n c r e a s e i n atmospheric carbon d i o x i d e accounts f o r o n l y approximately a t h i r d of t h a t r e l e a s e d . According to Lamb (1977), the r e s t c y c l e s i n t o the oceans and the biosphere. The r o l e of the oceans and the biosphere i n the a s s i m i l a t i o n of atmospheric carbon d i o x i d e i s not f u l l y understood due to a l a c k of knowledge about ocean dynamics and the e f f e c t s of d e f o r e s t a t i o n . Many r e s e a r c h e r s have concluded t h a t the oceans are the primary s i n k f o r f o s s i l f u e l carbon d i o x i d e (CC>2 Assessment Committee, 1983). At present carbon d i o x i d e d i f f u s e s back and f o r t h between the atmosphere and the ocean; the t r a n s f e r depend ent on the carbon d i o x i d e g r a d i e n t i n both the upper ocean and the atmosphere, and the a c t i o n of wind and waves. Carbon d i o x i d e i n the ocean and nearby atmosphere i s a l s o absorbed by phytoplankton through p h o t o s y n t h e s i s ( C O 2 Assessment Committee, 1983). S c i e n t i s t s s p e c u l a t e t h a t the f r a c t i o n of atmospheric carbon d i o x i d e taken up by the ocean, v i a d i f f u s i o n and phytoplankton could change i n a carbon d i o x i d e - r i c h e n v i r o n -ment (Ausubel, 1983). Determining whether t h i s change w i l l be a p o s i t i v e feedback ( i . e . , enhancing i n c r e a s e d atmospheric carbon d i o x i d e l e v e l s ) or a negative feedback ( i . e . , reducing the c o n c e n t r a t i o n ) r e q u i r e s a g r e a t d e a l o f knowledge about ocean dynamics. Due to the v a s t n e s s and depths of the oceans and the expense of data c o l l e c t i o n , knowledge of the ocean i s l i m i t e d . One such p o s s i b l e feedback mechanism i n v o l v e s the r e l a t i o n s h i p between oc e a n i c c i r c u l a t i o n , p r o d u c t i v i t y and atmospheric carbon d i o x i d e . S c i e n t i s t s s p e c u l a t e t h a t a g l o b a l warming may reduce o c e a n i c c i r c u l a t i o n because the l a t i t u d i n a l c o n t r a s t i n temperature t h a t d r i v e s t h i s c i r c u l a t i o n would decrease. If c i r c u l a t i o n were slowed, v a l u a b l e n u t r i e n t s i n the ocean depths may not c i r c u l a t e to s u r f a c e waters i n necessary q u a n t i t i e s . The r e s u l t would be reduced p h o t o s y n t h e s i s and t h e r e f o r e carbon normally a s s i m i l a t e d from s u r f a c e waters by phytoplankton would not be a s s i m i l a t e d . T h e r e f o r e , s u r f a c e waters and phytoplankton may be l e s s able to absorb i n c r e a s e d amounts of atmospheric carbon d i o x i d e (Baes, 1982). Evidence suggests t h a t l o n g - l i v e d p l a n t s , p a r t i c u l a r l y t r o p i c a l f o r e s t s a c t as s i g n i f i c a n t s i n k s f o r atmospheric carbon d i o x i d e . Whittaker and Likens (1973) estimate t r o p i c a l f o r e s t s accumulate 32 per cent of the t o t a l amount of carbon s t o r e d on 16 l a n d . According t o the Food and A g r i c u l t u r a l O r g a n i z a t i o n of the United N a t i o n s , these f o r e s t s are being c u t down a t a r a t e of 110,000 sq. km per year (IIASA, 1981). Lemon (1977) c a u t i o n s t h a t because regrowth i n t r o p i c a l f o r e s t s o ccurs so q u i c k l y , t here i s some c o n t r o v e r s y whether d e f o r e s t a t i o n r e s u l t s i n a net l o s s o f carbon d i o x i d e a s s i m i l a t o r s . 2.3 E f f e c t s o f Increased Atmospheric Carbon Dioxide Why should we be concerned about the steady i n c r e a s e i n f o s s i l f u e l consumption and the a s s o c i a t e d i n c r e a s e i n atmospheric carbon d i o x i d e ? We cannot see, smell or t a s t e t h i s gas, nor does i t a f f e c t our h e a l t h a t these c o n c e n t r a t i o n s , or change the c o l o r o f the sky. I n d u s t r i a l s a f e t y l i m i t s i n the United S t a t e s are now 5,000 ppm f o r c h r o n i c exposure to carbon d i o x i d e . Some energy e f f i c i e n t houses are estimated to have carbon d i o x i d e c o n c e n t r a t i o n s of almost 1,500 ppm. Even the most generous estimates of p o s s i b l e f u t u r e c o n c e n t r a t i o n s of atmospheric carbon d i o x i d e do not approach these l e v e l s ( C l a r k e t a l . , 1982). The reason f o r concern i s t h a t the atmospheric carbon d i o x i d e p r o v i d e s a b a r r i e r to the escape o f heat t h a t i s r a d i a t e d from the e a r t h . The incoming shortwave v i s i b l e and u l t r a v i o l e t r a d i a t i o n from the sun i s not a f f e c t e d by the carbon d i o x i d e but the outgoing longwave thermal i n f r a r e d r a d i a t i o n from the Earth's s u r f a c e i s absorbed and r e r a d i a t e d back to Ear t h (see F i g u r e 5 ) . Heat, normally r a d i a t e d i n t o o u t e r space 1 7 earth NORMAL C0 9 CONTENT INCREASED C0 2 CONTENT FIGURE 5: The effect of atmospheric carbon dioxide on incoming and outgoing radiation. Short wavelength solar energy strikes the earth and is transformed into longwave heat radiation, some of which i s absorbed and reradiated back to the earth by the carbon dioxide in the atmosphere. As carbon dioxide content increases more heat is retained and the atmosphere becomes warmer. SOURCE: G. Tyler M i l l e r , 1975, p. E5. i 18 i s trapped j u s t as the g l a s s i n a greenhouse t r a p s heat. This i s why the warming t h a t could be caused by i n c r e a s e d atmospheric carbon d i o x i d e has been r e f e r r e d to as the "greenhouse e f f e c t " . In f a c t , the analogy i s not q u i t e c o r r e c t because carbon d i o x i d e does not t r a p heat the way g l a s s i n a greenhouse does. In a greenhouse, the g l a s s p r o v i d e s a p h y s i c a l b a r r i e r t r a p p i n g s e n s i b l e thermal energy so t h a t i t can not be convected away from the warm s u r f a c e s w i t h i n the e n c l o s u r e . Schneider (1977) notes t h a t the f i r s t 10% i n c r e a s e i n atmospheric carbon d i o x i d e o c c u r r e d over a p e r i o d of approximately 110 y e a r s . I f the e x p o n e n t i a l nature of the consumption of f o s s i l f u e l s c o n t i n u e s the next 10% i n c r e a s e could occur i n o n l y 20 years and the next 10% i n o n l y 10 y e a r s . The continued use of f o s s i l f u e l s and the estimated i n c r e a s e i n atmospheric carbon d i o x i d e l e a d many s c i e n t i s t s to s p e c u l a t e on the e f f e c t s of what could be a "runaway greenhouse" - a green-house t h a t gets h o t t e r and h o t t e r , e v e n t u a l l y burning e v e r y t h i n g i n s i d e i t , because the heat i n p u t c o n t i n u e s to i n c r e a s e and no heat i s being d i s s i p a t e d . I t i s u n l i k e l y t h a t the e a r t h w i l l become a "runaway greenhouse" because the atmosphere would become s a t u r a t e d with carbon d i o x i d e or o t h e r pools such as the ocean would i n c r e a s e t h e i r r a t e of carbon d i o x i d e and heat exchange with the atmosphere. There i s g e n e r a l agreement amongst s c i e n t i s t s t h a t i f carbon d i o x i d e c o n t i n u e s to c o l l e c t i n the atmosphere, the 19 GAST"*" w i l l i n c r e a s e . Because a g l o b a l warming has i m p l i c -a t i o n s f o r atmospheric c i r c u l a t i o n p a t t e r n s , p r e c i p i t a t i o n p a t t e r n s and could u l t i m a t e l y a f f e c t many human a c t i v i t i e s , t h ere i s a reason to be concerned. 2.4 "But the Ear t h i s C o o l i n g " and Other C o n t r o v e r s i e s Perhaps c o o l i n g e f f e c t s , such as changes i n the Earth's o r b i t or v o l c a n i c e r u p t i o n s , w i l l o f f s e t the e f f e c t s o f a carbon d i o x i d e - i n d u c e d warming. Indeed, s i n c e 1940 r e c o r d s show th a t the average s u r f a c e temperature over most o f the E a r t h has decreased. Some a n a l y s t s b e l i e v e a c o o l i n g c y c l e , perhaps due to a i r b o r n e a e r o s o l s or v o l c a n i c dust d e c r e a s i n g atmospheric transparency, has masked the u n d e r l y i n g warming trend t e m p o r a r i l y (Budyko, 1978; Lamb, 1977; Mercer, 1978; Mead & K e l l o g g , 1980). Soon, these a n a l y s t s say, the f u l l e f f e c t s o f in c r e a s e d atmospheric carbon d i o x i d e w i l l predominate over the " c l i m a t i c n o i s e " . F i g u r e 6 i l l u s t r a t e s : (1) the decrease i n mean g l o b a l temperature s i n c e 1940 and (2) the range o f f l u c t u a t i o n o f " c l i m a t e n o i s e " that can be expected with and without the carbon d i o x i d e e f f e c t . Idso (1982) - a " v o c a l m i n o r i t y o f v i r t u a l l y one" (Budiansky, 1982), c l a i m s the decrease i n temperature s i n c e 1940 i s evidence s c i e n t i s t s r e a l l y do not know the e f f e c t s of i n c r e a s e d atmospheric carbon d i o x i d e on c l i m a t e . TT GAST i s the g l o b a l average s u r f a c e temperature, p r e s e n t l y estimated to be 15° C (IIASA, 1981). More a c c u r a t e l y , the term "mean" r a t h e r than average should be used. 20 1850 1900 1950 2000 2050 2100 FIGURE 6l T n e decrease i n mean global temperature since 1940 and the possible range of f l u c t u a t i o n with or with-out the carbon dioxide e f f e c t . SOURCE: Council on Environmental Quality, 1981, p. 10. (Based on unavailable source: M i t c h e l l , J r . , J.977) . 21 Other s c i e n t i s t s argue t h a t many f a c t o r s lead t o c l i m a t i c v a r i a t i o n over the long term, such as changes i n the s o l a r constant or c o n t i n e n t a l d r i f t , and t h a t carbon d i o x i d e i s o n l y another f a c t o r t h a t w i l l be i m p e r c e p t i b l e amongst the o t h e r s . Others p o i n t out th a t carbon d i o x i d e i s d i f f e r e n t from o t h e r c l i m a t i c i n f l u e n c e s because i t i s the f i r s t human-induced change t h a t may have g l o b a l impacts. M i t c h e l l (1978) suggests t h a t i n c r e a s e d atmospheric carbon d i o x i d e w i l l extend the presen t i n t e r g l a c i a l " ' " p e r i o d i n which we are l i v i n g but t h a t the n a t u r a l c y c l e s o f the Earth w i l l e v e n t u a l l y predominate. H i s t o r i c evidence r e v e a l s t h a t there has been a s e r i e s o f i c e ages i n t e r r u p t e d by p e r i o d s o f warming of c o n t r o v e r s i a l o r i g i n (but probably not due to carbon d i o x i d e ) . Carbon d i o x i d e - i n d u c e d warming may lead t o the f i r s t " s u p e r - i n t e r g l a c i a l " l a s t i n g much lo n g e r and perhaps b r i n g i n g warmer c o n d i t i o n s than any oth e r i n t e r g l a c i a l ( M i t c h e l l , 1978). Schwarzbach (1963) suggests t h a t many b e l i e v e we may be l i v i n g i n a " p o s t g l a c i a l " p e r i o d i n which g l a c i a t i o n w i l l not re o c c u r r a t h e r than an i n t e r g l a c i a l . Another c o n t r o v e r s i a l i s s u e i n v o l v e s the a b i l i t y o f the ocean to s t o r e heat: the f i r s t three metres of the ocean are estimated to s t o r e as much heat as the atmosphere ( B a r n e t t i n G r i b b i n , 1978). Perhaps the oceans co u l d a c t as enormous r e c e p t a c l e s absorbing more heat, thereby s t a b i l i z i n g the T~i I n t e r g l a c i a l r e f e r s t o the warm p e r i o d s t h a t s c i e n t i s t s b e l i e v e have a l t e r n a t e d with c o l d , g l a c i a l p e r i o d s d u r i n g the l a s t m i l l i o n years (Massachusetts I n s t i t u t e of Technology, 1971). 22 c l i m a t e f o r some time even though atmospheric carbon d i o x i d e were to i n c r e a s e . However, although the a b s o r p t i o n o f heat i n t o the wind-mixed l a y e r i s q u i t e r a p i d , the t r a n s f e r o f heat to deeper l e v e l s i s much slower. Quite p o s s i b l y the atmospheric temperature could reach e q u i l i b r i u m with the wind-mixed l a y e r w i t h i n a decade or so, thus d e l a y i n g the atmospheric warming f o r o n l y a s h o r t while ( N a t i o n a l Academy of S c i e n c e , 1979). G e n e r a l l y , most s c i e n t i s t s agree t h a t g i v e n our r e l i a n c e on f o s s i l f u e l s , atmospheric carbon d i o x i d e w i l l c o n t i n u e to i n c r e a s e . Much more c o n t r o v e r s i a l are the "how much" and "how f a s t " q u e s t i o n s and q u e s t i o n s concerning the impacts. 2.5 Major U n c e r t a i n t i e s There are major u n c e r t a i n t i e s i n v o l v e d i n the carbon d i o x i d e - i n d u c e d g l o b a l warming i s s u e t h a t should not be over-looked or deemphasized. In p r e v i o u s s e c t i o n s 2.1 through 2.4, the f o l l o w i n g u n c e r t a i n t i e s have been d i s c u s s e d : (a) S o c i a l and economic u n c e r t a i n t i e s - The r a t e a t which f o s s i l f u e l s are consumed. - The types o f energy sources used i n the f u t u r e . - The r a t e a t which d e f o r e s t a t i o n o c c u r s . (b) B i o p h y s i c a l response u n c e r t a i n t i e s - C o o l i n g e f f e c t s t h a t may o f f s e t warming. - The r a t e at which warming co u l d o c c u r . - The amount of warming t h a t c o u l d occur. 23 - The r a t e of biomass uptake i n c l u d i n g the u n c e r t a i n t y a s s o c i a t e d with the impacts o f d e f o r e s t a t i o n . - The oc e a n i c response to in c r e a s e d atmospheric carbon d i o x i d e . 2 . 6 B e n e f i c i a l o r Harmful? W i l l a carbon d i o x i d e - i n d u c e d warming be b e n e f i c i a l o r harmful to s o c i e t y ? Answering t h i s q u e s t i o n i s not easy; probably some s e c t o r s of s o c i e t y w i l l b e n e f i t but o t h e r s w i l l not. S i m i l a r l y , c e r t a i n c o u n t r i e s o r groups of people may b e n e f i t and o t h e r s may not. The b e n e f i t s or harm t h a t could r e s u l t need t o be examined f o r each s e c t o r and each r e g i o n . Changes i n one r e g i o n that c o u l d have s i g n i f i c a n t impacts i n another r e g i o n a l s o need to be examined. For example, much of the world depends on s u r p l u s g r a i n p r o d u c t i o n i n the United S t a t e s and Canada. Even a s l i g h t r e d u c t i o n i n t h i s a v a i l a b l e s u r p l u s could mean h a r d s h i p f o r many c o u n t r i e s (Mead & K e l l o g g , 1980). Much of the remainder of t h i s t h e s i s i s d i r e c t e d a t determining the impacts - both b e n e f i c i a l and harmful - of a carbon d i o x i d e - i n d u c e d warming i n one r e g i o n : the Vancouver area. In order to f u l l y answer the q u e s t i o n posed - W i l l a carbon d i o x i d e - i n d u c e d warming be b e n e f i c i a l o r harmful to s o c i e t y ? - many such s t u d i e s of many r e g i o n s w i l l be r e q u i r e d . Even when these s t u d i e s are complete, the q u e s t i o n w i l l be d i f f i c u l t to answer c o n c l u s i v e l y because there w i l l s t i l l remain 24 many uncertainties about the possible impacts, but more importantly because answers to such questions involve value-based personal judgements of what i s harmful and what i s b e n e f i c i a l . In addition, a carbon dioxide-induced warming may be very harmful to society i f we are not prepared and ready for the r e s u l t i n g changes. If however, we can anticipate and plan how to take advantage of the changes, a carbon dioxide induced warming may be b e n e f i c i a l . 25 CHAPTER 3 DEVELOPMENT OF CLIMATIC SCENARIOS FOR VANCOUVER Chapter 3 begins by examining the r o l e o f s c e n a r i o s i n the study of a g l o b a l warming. The chapter then examines the use of c l i m a t e models i n s c e n a r i o development, and develops a c l i m a t e s c e n a r i o f o r Vancouver based on these models. The use of p a l e o c l i m a t i c data i n the development of s c e n a r i o s i s then examined and what i s known about the c l i m a t e of the West Coast of North America i s used to develop a s c e n a r i o f o r Vancouver's c l i m a t e . The chapter then examines the l i t e r a t u r e t h a t has analysed r e c e n t recorded data i n order to develop a t h i r d c l i m a t e s c e n a r i o f o r Vancouver. F i n a l l y , the s c e n a r i o s developed by the three methods are summarized. 3.1 What are s c e n a r i o s ? S c e n a r i o s are d e s c r i p t i o n s o f a l t e r n a t i v e f u t u r e s . Kahn and Weiner (1967), the f i r s t to use the term ' s c e n a r i o ' i n pla n n i n g d u r i n g the 1950's, d e f i n e d i t as "a h y p o t h e t i c a l sequence of events c o n s t r u c t e d f o r the purpose of f o c u s i n g a t t e n t i o n on c a u s a l processes and d e c i s i o n p o i n t s " (p. 6 ) . Sce n a r i o s are not intended t o p r e d i c t the f u t u r e but r a t h e r to make people aware of a range of p o s s i b l e f u t u r e s and the circumstances that may b r i n g these f u t u r e s about. Essen-t i a l l y , s c e n a r i o s are not an end i n themselves but r a t h e r are 26 considered an a i d to t h i n k i n g . A n a l y s t s , policy-makers and o t h e r s are encouraged to broaden t h e i r range o f t h i n k i n g by (1) c o n s i d e r i n g many a l t e r n a t i v e f u t u r e s and (2) determining how t h e i r a c t i o n s may prevent, d i v e r t or f a c i l i t a t e the f u t u r e d e s c r i b e d by a s c e n a r i o . A b a s i s i s provided from which to develop a n t i c i p a t o r y , f l e x i b l e approaches t o management and policy-making and f o r e v a l u a t i n g p r e s e n t s t r a t e g i e s . T h i s i s not to imply the f u t u r e w i l l be without s u r p r i s e s but such an approach helps to d i s c e r n s u r p r i s e s before they f u l l y develop. 3.2 How are s c e n a r i o s developed? A v a s t number of s c e n a r i o s can o f t e n be imagined. S e l e c t i o n of a key few should be based on the f o l l o w i n g c r i t e r i a : r e l e v a n c e to the s u b j e c t a t hand, c r e d i b i l i t y , u s e f u l n e s s and i n t e l l i g i b i l t y (Wilson, 1978). U s u a l l y more than one s c e n a r i o i s developed to i n d i c a t e t h a t there i s a range o f p o s s i b l e f u t u r e s . Wilson suggests using at l e a s t f o u r s c e n a r i o s i n c l u d i n g (1) a benchmark o r " s u r p r i s e - f r e e " s c e n a r i o ; (2) a s c e n a r i o to demonstrate what can be expected i f present p a t t e r n s c o n t i n u e ; (3) a "best o f a l l p o s s i b l e worlds" s c e n a r i o ; and (4) a "worst o f a l l p o s s i b l e worlds" s c e n a r i o . When onl y two s c e n a r i o s are developed, one o f t e n i s pe r c e i v e d as 'good' and the other as 'bad 1. When three are used, the one t h a t can be i d e n t i f i e d as the 'middle of the road' s c e n a r i o i s o f t e n assumed to be most d e s i r a b l e . A t t a c h i n g value 27 i n t h i s way to c e r t a i n s c e n a r i o s should be avoided; s c e n a r i o s are not intended to suggest or p a i n t a p i c t u r e of what the f u t u r e should be, but r a t h e r what i t could be. Because of the nature of the task - working wi t h sketchy data about p o s s i b l e f u t u r e s and c o n t r a d i c t i n g p o s s i b i l i t i e s -s c e n a r i o development n a t u r a l l y i n v o l v e s some judgement i n the s e l e c t i o n and use of d a t a . To some, the development of s c e n a r i o s may seem to be "educated guesswork". 3.3 How can s c e n a r i o s be used i n the study of g l o b a l warming?  Scen a r i o s can be developed to d e s c r i b e a p o s s i b l e range o f c l i m a t i c c o n d i t i o n s t h a t could occur with an i n c r e a s e i n the g l o b a l average s u r f a c e temperature. S o c i a l , economic and environmental c o n d i t i o n s can then be evaluated i n terms of these a l t e r n a t e f u t u r e s and subsequently, management p o l i c i e s can be reviewed. C l a r k (1982) c a u t i o n s t h a t " l i k e any t o o l , s c e n a r i o approaches can be misused to provide s e n s a t i o n a l i s t treatments of the carbon d i o x i d e i s s u e . But r e s p o n s i b l y a p p l i e d , s c e n a r i o s have a l s o been an e f f e c t i v e means of b r i n g i n g the best of s c i e n t i f i c understanding to bear on i s s u e s t h a t p o l i c y people can do something about " (p. 35). S c e n a r i o s can be developed to i n d i c a t e a range of p o s s i b l e c o n d i t i o n s during a s e t p e r i o d of time and/or i n a p a r t i c u l a r r e g i o n . U s u a l l y a time p e r i o d of a hundred years i s u s e f u l . For purposes of e v a l u a t i n g the s o c i a l , economic and 28 environmental i m p l i c a t i o n s of the c l i m a t e s c e n a r i o s , a time p e r i o d of approximately 80-100 years i s u s e f u l because: (1) the estimated d o u b l i n g time f o r atmospheric carbon d i o x i d e i s approximately the mid-20th c e n t u r y o r 70 to 80 years from now (IIASA, 1981); (2) g l a c i a l response to a g l o b a l warming i s estimated to begin about 50 years from now when c r i t i c a l warm temperatures are reached (Mercer, 1978); and (3) major i n f r a s t r u c t u r e such as dams, dykes, t o x i c waste d i s p o s a l s i t e s and t r a n s p o r t a t i o n systems have u s e f u l l i f e t i m e s o f approximately 100 y e a r s . Many of these p r o j e c t s could spend most of t h e i r u s e f u l l i v e s under a l t e r e d or a l t e r i n g c l i m a t i c c o n d i t i o n s . S c e n a r i o s should not o n l y i n d i c a t e the magnitude o f change but the r a t e o f change over time. S o c i a l , environmental and economic response to change i s o f t e n l e s s t r a u m a t i c i f change oc c u r s g r a d u a l l y over a long time p e r i o d r a t h e r than suddenly over a s h o r t time p e r i o d . C l i m a t i c s c e n a r i o s f o r p a r t i c u l a r r e g i o n s can be ve r y u s e f u l . There i s g e n e r a l agreement amongst r e s e a r c h e r s t h a t the impacts of a g l o b a l warming would vary s i g n i f i c a n t l y from r e g i o n to r e g i o n even w i t h i n the same l a t i t u d i n a l zone ( K e l l o g g , 1978, 1979, 1982; P i t t o c k & S a l i n g e r , 1982; Wigley, Jones & K e l l y , 1980). T h e r e f o r e , i n order t o develop a p p r o p r i a t e energy p o l i c i e s and s o c i a l and economic s t r a t e g i e s , policymakers and plann e r s need to understand the p o s s i b l e r e g i o n a l impacts. 29 The i n f o r m a t i o n contained i n c l i m a t i c s c e n a r i o s depends on the purpose o f the s c e n a r i o s . In order t o determine the i m p l i c a t i o n s f o r a g r i c u l t u r e , f l o o d i n g , water supply and human se t t l e m e n t , the f o l l o w i n g i n f o r m a t i o n i s u s e f u l : ( i ) A g r i c u l t u r e - P r e c i p i t a t i o n , temperature and s o i l m o i sture c o n d i t i o n s on a seasonal b a s i s i n d i c a t e growing c o n d i t i o n s . ( i i ) F l o o d i n g - P r e c i p i t a t i o n and temperature c o n d i t i o n s on a monthly b a s i s i n d i c a t e r u n o f f c o n d i t i o n s and p o t e n t i a l sea l e v e l r i s e . ( i i i ) Water Supply - P r e c i p i t a t i o n and temperature c o n d i t i o n s on a seasonal b a s i s i n d i c a t e p o s s i b l e shortages o r s u r p l u s e s , storage needs and p o s s i b l e h e a l t h concerns. (i v ) Human Settlement - P r e c i p i t a t i o n , temperature, l o c a l wind and fog c o n d i t i o n s on a seasonal b a s i s i n d i c a t e p o s s i b l e c o n s t r a i n t s to human sett l e m e n t such as r u n o f f , f l o o d i n g , water supply problems, t r a n s p o r t a t i o n r e s t r i c t i o n s and p o l l u t i o n problems. T h e r e f o r e , f o r purposes o f t h i s t h e s i s , the c l i m a t i c s c e n a r i o s are most u s e f u l i f they i n d i c a t e p r e c i p i t a t i o n , temperature, s o i l , m oisture, and fog c o n d i t i o n s and the seasonal v a r i a t i o n of each of those c o n d i t i o n s . Depending on the method used to determine the s c e n a r i o s , i t i s not always p o s s i b l e to i n d i c a t e how a l l of these c o n d i t i o n s may be a f f e c t e d . K e l l o g g and Schware (1981) recommend t h a t s c e n a r i o s be developed using a l l a v a i l a b l e evidence i n c l u d i n g the r e s u l t s o f 30 climate model experiments and studies of past climate change. Unfortunately, these data w i l l not always be available or i f available, may be fragmentary and sometimes contradictory. The use of data w i l l involve some s u b j e c t i v i t y on the part of the scenario developer. 3.4 How are climate scenarios developed? There are three methods described in the l i t e r a t u r e for developing regional scenarios of c l i m a t i c change: (1) the use of numerical models of the global c i r c u l a t i o n system combined with knowledge of the present c l i m a t i c influences, (2) the use of paleoclimatic evidence, and (3) the use of recent recorded data. Pittock and Salinger (1982) used each of these methods in trying to determine the impact of global warming on Aus t r a l i a and New Zealand. The authors r e a l i z e d none of the methods were capable of predicting c l i m a t i c conditions with any cert a i n t y , thus they suggest using as many methods as possible and then comparing the r e s u l t s . In t h e i r study a l l three methods yielded s i m i l a r r e s u l t s which increased confidence i n the methods. The following explains each of the methods and how they are used to come to some conclusions about the implications of global warming for the Vancouver region. 31 3 . 5 The use of climate models 3 . 5 . 1 The search for suitable models S c i e n t i s t s r e a d i l y admit the c l i m a t i c system i s one of the most complex of natural systems (see Figure 7 ) . In order to better understand the c l i m a t i c system and test the e ffects of increasing atmospheric carbon dioxide, a model or representation of the r e a l system i s useful. Such a model can be a three dimensional physical, or a numerical, or analogous representation. Designing a three dimensional physical model i s d i f f i c u l t because no laboratory i s large or complex enough to contain such a model. Because of these l i m i t a t i o n s , s c i e n t i s t s look for other ways of representing the c l i m a t i c system: through numerical representation of the processes involved or by finding analogous situations to study. 3 . 5 . 2 The Atmospheres of Other Planets as Models The atmospheres of other planets can serve as 'models' of what could happen on Earth. Of course conditions can not be manipulated as they could in an ideal model, but various exi s t i n g conditions can be studied. Examination of data from space probes of Mars and Venus has i l l u s t r a t e d a r e l a t i o n s h i p between carbon dioxide and surface temperature: Venus with an atmosphere composed of 97% carbon dioxide has a surface temperature of 720° Kelvin. Earth's atmosphere contains about 0.032% carbon dioxide and has a surface temperature of 288° Kelvin. (The freezing point of water i s 2 7 3 . 1 6 ° Kelvin.) These Solar radiation Atmospheric optical properties Surface roughness Current Mixing depth FIGURE 7 The c o m p l e x i t y of the c l i m a t i c s y s t e m . S o u r c e : K e l l o g g and S c h n e i d e r , 1974, p. 1164. s u r f a c e temperatures c o i n c i d e f a i r l y w e l l with s c i e n t i f i c hypotheses of the e f f e c t s of carbon d i o x i d e i n the atmosphere ( C 0 2 / C l i m a t e Review Panel, 1982; S i e d e l & Keyes, 1983; Budyko, i n G r i b b i n , 1978). 3.5.3 Computer M o d e l l i n g ; A more complex model i s a v a i l a b l e : the g l o b a l c l i m a t e can be simulated by using mathematical r e p r e s e n t a t i o n s of the processes i n v o l v e d with the a i d of a computer. These models attempt to s i m u l a t e the major processes i n v o l v e d i n c l i m a t e which a r e : ( i ) incoming s o l a r r a d i a t i o n ( i i ) d i s t r i b u t i o n of energy over e a r t h ' s s u r f a c e ( i i i ) the e f f e c t of s u r f a c e albedo (i v ) the r a d i a t i v e e f f e c t s of v a r i o u s gases i n the atmosphere ( i n c l u d i n g carbon d i o x i d e ) and (v) the heat exchanges between the atmosphere, Earth and the oceans. Due to our l i m i t e d knowledge of c l i m a t e theory and computer l i m i t a t i o n s , c l i m a t e models must s i m p l i f y or omit p a r t s o f the system e n t i r e l y . In p a r t i c u l a r , ocean dynamics are not w e l l understood thus are u s u a l l y modelled r a t h e r u n s o p h i s t i -c a t e d l y with l i t t l e i n t e r a c t i o n with the atmosphere. Despite l i m i t a t i o n s , models have been developed which s i m u l a t e present c l i m a t e s reasonably w e l l ( i n c l u d i n g seasonal v a r i a t i o n ) , and i c e age c o n d i t i o n s f a i r l y r e a l i s t i c a l l y . A l s o encouraging i s the 34 knowledge t h a t models developed by v a r i o u s r e s e a r c h e r s have y i e l d e d s i m i l a r r e s u l t s . Idso (1982) claims the s i m i l a r r e s u l t s are to be expected because a l l of the r e s e a r c h e r s have made the same i n a c c u r a t e assumptions independently. Var i o u s models have been developed to determine the impact of in c r e a s e d atmospheric carbon d i o x i d e . To determine these impacts, c e r t a i n assumptions must be made concerning such f a c t o r s as (1) the r a t e and amount of f u t u r e f o s s i l f u e l consumption (based on p o p u l a t i o n and economic growth), (2) the amount of carbon d i o x i d e absorbed by the biomass and the oceans and (3) the impact o f c l o u d s , (4) the r o l e of topography and (5) the amount of heat t r a n s f e r r e d by ocean c u r r e n t s . U s u a l l y a range of assumptions i s used, y i e l d i n g a number of p o s s i b l e outcomes (see Hansen e t a l . , 1981, and Hoffman e t a l . , 1983). The EPA r e p o r t by S i e d a l and Keyes (198 3) i n t e g r a t e d three models - a world energy model, an atmospheric temperature model and a carbon c y c l e model - to determine the c l i m a t i c impact of a range of energy f u t u r e s . F i g u r e 8 i l l u s t r a t e s the study methodology used. Probably the most advanced models used are the G l o b a l C i r c u l a t i o n Models o r G.C.M.'s (see Manabe & Wetherald, 1975, and 1980). With these models the v a r i o u s mathematical r e p r e s e n t a t i o n s o f the r o l e of carbon d i o x i d e are manipulated. In many cases, the c o n c e n t r a t i o n of atmospheric carbon d i o x i d e has been doubled and the impacts observed. WORLD ENERGY MODEL • estimate changes in population and productivity • estimate, -fuel costs and demand . estimate. COi emission rates • estimate energy t&aeincy /mprcA/MneHte 35 ATMOSPHERIC TEMPERATURE MODEL . estimate COa - Temperature sensitivity . estimate thermal dif-fusity * project concentrations erf other greenhouse gase£. CARBON CYCLE MODEL . simulate atmospheric, oceanic and laiospheric stocKs • estfmate COz emissions • estimate impact o{ land clearing and re-farestation FIGURE 8: I n t e g r a t i o n of t h r e e m o d e l s - a w o r l d energy m o d e l , an a t m o s p h e r i c t e m p e r a t u r e model and a c a r b o n c y c l e m o d e l . S o u r c e : S i e d e l and K e y e s , 1983, p . 3 - 2 . 36 3.5.4 R e s u l t s o f Computer Models: C l a r k (1982) has summarized the r e s u l t s o f 34 d i f f e r e n t c l i m a t e models (see F i g u r e 9 ) . A l l o f the models show an i n c r e a s e i n GAST with a d o u b l i n g o f atmospheric carbon d i o x i d e . Although p r e d i c t e d GAST v a l u e s v a r y , there i s some concensus d e v e l o p i n g . G e n e r a l l y the f o l l o w i n g statements can be made: ( i ) The GAST would i n c r e a s e by 0.8°C t o 3.6°C with a value o f 2.5°C being widely quoted (Manabe & Wetherald, 1975; Mead & K e l l o g g , 1980). 2.5°C a l s o i s the mean value i n F i g u r e 8. The most s i g n i f i c a n t f i n d i n g of the models i s the l a t i t u d i n a l v a r i a t i o n i n warming: the Poles would warm a p p r e c i a b l y more (10°C to 15°C) than the Equator (1.5°C t o 3°C). T h i s i s due to m e l t i n g i c e , i n c r e a s i n g water vapour and the subsequent change i n the Earth's albedo p r o v i d i n g p o s i t i v e feedback ( S i e d e l & Keyes, 1983; and Watts, 1980, D i c k i n s o n i n C l a r k , 1982). Figure 10 i l l u s t r a t e s the probable l a t i t u d i n a l v a r i a t i o n i n temperature. ( i i ) Because the temperature g r a d i e n t between the Poles and the equator would be l e s s than a t p r e s e n t , the s t r e n g t h o f wind p a t t e r n s and ocean c u r r e n t s t h a t p r e s e n t l y attempt to e q u a l i z e t h i s imbalance, would decrease. ( i i i ) Although there i s c o n f l i c t i n g evidence (MacDonald, 198 2), i t appears warming i n the A r c t i c would be g r e a t e r i n winter than summer because heat s t o r e d by the ocean would be r e l e a s e d i n winter ( D i c k i n s o n i n C l a r k , 1982). 37 Source-- A^CQ . Plass (1956) . 3.7 Kaplan (1960) 1.7 Moller (1963) 9.6 Manabe and Wetherald (1967) 2.3 Manabe (1971) 1.9 Rasool and Schneider (1971) 0.8 Ramanathan (1974) 1.5 ' Sellers (1974) 1.3 Weare and Snell (1974) 0.7 Manabe and Wetherald (1975) 2.9 Schneider (1975) 2.9 Temkin and Snell (1976) 1.7-Wang et al. (197fi)-FTT 3.2 _ Wann et al. (1976)-FTA 2.1 ' Augustsson and Ramanathan (1977)-FTT 3.2 Autrustsson and Ramanathan (1977)-FTA 2.0 Hansen (1978) 3.5 OhrinK and Adler (1978) 0.8 Rowntree and Walker (1978) 1.4 Haiuh and Pyle (1979) 2.5' Hansen (1979) 3.9 Hunt and Wells (19791 1.8 MatDonald et al. (1979) . .2 .4-Manabe and Stouffer (1979) "2.0' ' Newell and Dopplick (1979) 0.25 Potter (1979) 2.1-; Ramanathan et al. (1979) ' 3.0 G;:tes and Cook (1980) 0.2 Idso(1980) 0.1 Manabe and Wetherald (1980) 3.0 Cess and Goldenberg (1981) 1.5-1.8 Hansen et al. (1981 )-FTT 2.8 Hansen et al. (1981 )-FTA 1.4 Wetherald and Manabe (1981) 2.4-^FIGURE 9: E s t i m a t e s of average s u r f a c e a i r t e m p e r a t u r e change due t o a doub'Htiig of ca rbon d i o x i d e i n 34 c l i m a t e m o d e l s . S o u r c e : Adapted f rom C l a r k , 1 9 8 2 , p . 2 4 . 38 30 40 50 60 70 Latitude (degrees I FIGURE 10: P r o b a b l e l a t i t u d i n a l v a r i a t i o n i n t e m p e r a t u r e i n -c r e a s e a c c o r d i n g to c l i m a t i c m o d e l s . S o u r c e : M a c D o n a l d , 1 9 8 2 , p . 1 9 5 . 39 (i v ) A number of c l i m a t i c models i n d i c a t e an i n c r e a s e i n the a c t i v i t y of the h y d r o l o g i c a l c y c l e with p r e c i p i t a t i o n i n c r e a s e s of about 10 per cent i n a band poleward of 40° l a t i t u d e (MacDonald, 1982). (v) D e p l e t i o n by m e l t i n g o f the A r c t i c i c e (mostly f l o a t i n g i c e ) would occur much sooner than i n the A n t a r c t i c where most of the i c e i s more than 250 m t h i c k and land-based. At present the c l i m a t i c asymmetry of the two hemispheres i s r e s p o n s i b l e f o r a whole s e t of c l i m a t i c phenomena. If the north pole were to be g e n e r a l l y i c e - f r e e while the south pole remained i c e - c o v e r e d , t h i s assymmetry would be emphasized. Atmospheric c i r c u l a t i o n p a t t e r n s would a d j u s t , p o s s i b l y s h i f t i n g c l i m a t i c zones 200 o r more k i l o m e t r e s poleward. For the m i d - l a t i t u d e s t h i s i n d i c a t e s a p o t e n t i a l l y s i g n i f i c a n t warming and d r y i n g (Watts, 1980; Flohn i n C l a r k , 1982). The G.C.M.'s have not been used to estimate when an i n c r e a s e of 2.5°C i n the GAST can be expected. At p r e s e n t the models are simply run with doubled atmospheric carbon d i o x i d e l e v e l s and the r e s u l t s observed. In a r e a l world s i t u a t i o n , of course, the carbon d i o x i d e l e v e l s would i n c r e a s e g r a d u a l l y . Estimates can be made of the probable timing of a 2.5°C i n c r e a s e , based on present energy usage, p o p u l a t i o n and economic growth and o t h e r f a c t o r s . These es t i m a t e s show t h a t u n l e s s there are major changes i n g l o b a l energy sources o r p o l i c y , a 2.5°C warming co u l d occur by the middle of the next c e n t u r y ( S i e d e l & Keyes, 1983; and IIASA, 1981). The concensus i s t h a t 40 the warming w i l l take p l a c e g r a d u a l l y i n a l i n e a r manner but the p o s s i b i l i t y of the warming o c c u r r i n g i n a s e r i e s of steps cannot be r u l e d out. 3.5.5 I m p l i c a t i o n s f o r Vancouver's Climate; The f o l l o w i n g s e c t i o n s w i l l examine what the r e s u l t s o f the computer models suggest f o r the c l i m a t e of Vancouver. Determining the impacts of g l o b a l warming on a p a r t i c u l a r r e g i o n i s not a simple matter of adding 2.5°C to present temperatures. An i n c r e a s e i n GAST w i l l have r e p e r c u s s i o n s i n the atmospheric, h y d r o s p h e r i c and c r y o s p h e r i c 1 systems t h a t c o u l d l e a d to c l i m a t i c change t h a t we can o n l y attempt to e s t i m a t e . The r e g i o n a l c l i m a t i c changes w i l l depend on many f a c t o r s i n c l u d i n g p r o x i m i t y to water bodies, topography and p r e v a i l i n g winds. At p r e s e n t the G.C.M.'s do not i n c l u d e these l o c a l f a c t o r s nor has another model been developed to r e p r e s e n t r e g i o n a l c h a r a c t e r i s t i c s . The complexity of l o c a l systems and the expense of models are d e t e r r i n g f a c t o r s . However, the e x i s t i n g models do i n d i c a t e how the macro-climate i n the m i d - L a t i t u d e s may vary and t h i s can be combined with knowledge of l o c a l c l i m a t i c i n f l u e n c e s to develop s c e n a r i o s of a r e g i o n ' s c l i m a t e . 1. The cryosphere i s the p a r t of the world t h a t i s snow or i c e (Hoffman e t a l . , 1983). 3.5.6 The Present C l i m a t i c I n f l u e n c e s i n Vancouver; Vancouver's temperate c l i m a t e i s c h a r a c t e r i z e d by warm summers and g e n e r a l l y m i l d , cloudy r a i n y w i n t e r s . F i g u r e 11 summarizes e x i s t i n g c o n d i t i o n s . The f o l l o w i n g i n f l u e n c e s shape Vancouver's c l i m a t e : ( i ) Oceanic and topographic i n f l u e n c e s : The nearby ocean and c o a s t a l mountains s i g n i f i c a n t l y a f f e c t the r e g i o n ' s c l i m a t e d i s t i n g u i s h i n g i t from the c l i m a t e more t y p i c a l o f the r e s t of Canada i n the same l a t i t u d e . The ocean has a moderating e f f e c t on the l o c a l c l i m a t e because of i t s l a r g e thermal c a p a c i t y , which determines that ocean waters must absorb f i v e times as much thermal energy to r a i s e t h e i r temperature by the same amount as a comparable mass of d r y s o i l . When subsequently co o l e d , oceans have a tremendous amount of s t o r e d heat to be r e l e a s e d : a metre t h i c k l a y e r of ocean water when cooled by as l i t t l e as 0.1°C w i l l r e l e a s e enough heat to r a i s e the temperature of approximately a 30 m t h i c k a i r l a y e r by 10°C (Barry and C h o r l e y , 1982). T h e r e f o r e , the temperatures i n the Vancouver r e g i o n are moderated i n summer by the a b s o r p t i o n of heat by the nearby ocean. In winter, temperatures r a r e l y are very c o l d because of the r e l e a s e of s t o r e d heat by the ocean. A i r moving over the ocean f o r a time w i l l a l s o absorb m o i s t u r e . Thus Vancouver's incoming a i r w i l l o f t e n be m o i s t . Once t h i s moist a i r meets the c o a s t a l mountains and i s f o r c e d to 42 MONTH FIGURE 11: Annual mean, maximum and minimum t e m p e r a t u r e and p r e c i p i t a t i o n i n V a n c o u v e r . (Based on c l i m a t i c no rmals f o r 1 9 5 1 - 8 0 a t Vancouver I n t e r n a t i o n a l A i r p o r t ^ A t m o s p h e r i c Env i ronment S e r v i c e s , 1 9 8 2 ) . 43 r i s e , i t c o o l s and condenses l e a d i n g to cl o u d formation and p r e c i p i t a t i o n . ( i i ) C y c l o n i c i n f l u e n c e : Another major c l i m a t i c i n f l u e n c e i s c y c l o n i c a c t i v i t y . At a g l o b a l l e v e l c y c l o n i c a c t i v i t y p l a y s an important r o l e i n t r a n s p o r t i n g heat from warmer low l a t i t u d e s to c o o l e r high l a t i t u d e r e g i o n s . The E a r t h i s not warmed un i f o r m l y by the sun because the s o l a r z e n i t h angles at low l a t i t u d e s are on the average s m a l l e r than those a t high l a t i t u d e s . In an attempt to compensate f o r t h i s imbalance, the warm moist a i r a t the equator expands, r i s e s and flows poleward and the c o l d dry p o l a r a i r condenses, s i n k s and flows toward the equator. However, o n l y between the equator and about 30° i s the c i r c u l a t i o n system c l e a r l y dominated by north-south a i r movement as d e s c r i b e d . T h i s c i r c u l a t o r y system i s r e f e r r e d to as the Hadley c e l l . At the p o l e s , there i s b e l i e v e d to be a much weaker and l e s s p e r s i s t e n t c e l l with a s i m i l a r c i r c l a t o r y system. T h i s i s because the r o t a t i o n o f the Earth o r the C o r i o l i s e f f e c t d i s r u p t s the thermal c i r c u l a t i o n . As a r e s u l t the m e r i d i o n a l (north-south) c i r c u l a t i o n t h a t would be expected i f the C o r i o l i s e f f e c t d i d not e x i s t i s r e p l a c e d by zonal or l a t i t u d i n a l east-west c i r c u l a t i o n . In these areas dominated by zonal c i r c u l a t i o n , frequent l a r g e "eddies" o r c y c l o n i c d i s t u r b a n c e s p l a y an important r o l e i n t r a n s p o r t i n g heat from warmer to c o o l e r r e g i o n s (Barry and Chorley, 1982). These eddies form when the predominant w e s t e r l y winds i n the nor t h e r n and southern hemisphere develop troughs and r i d g e s 44 u l t i m a t e l y breaking up and forming eddies of moving a i r - the c l o c k w i s e moving eddies being high pressure a n t i c y c l o n e s and the c o u n t e r c l o c k w i s e moving edd i e s being low pressure c y c l o n e s . F i g u r e 12 shows s c h e m a t i c a l l y how these break-ups may occur. The reason f o r the break-ups and subsequent formation of c y c l o n e s and a n t i c y c l o n e s i s not c l e a r : the f a s t zonal flow appears to be u n s t a b l e . When the g e n e r a l g l o b a l c i r c u l a t i o n i s s t r o n g e s t i n winter, the break-ups occur more r e g u l a r l y (Barry and Chorley, 1982). In Vancouver, c y c l o n i c d i s t u r b a n c e s are very common, p a r t i c u l a r l y i n w i n t e r . Incoming warm moist a i r masses flow inward to the low pressure area, the a i r expands and r i s e s , c o o l i n g as i t does so. As i t c o o l s the water vapour c a p a c i t y of the a i r decreases which o f t e n l e a d s to s a t u r a t i o n , condensation, c l o u d formation and p r e c i p i t a t i o n . In summer, with a lower temperature g r a d i e n t between the p o l e s and equator, the Westerly flow i s weakened thus there i s l e s s c y c l o n i c a c t i v i t y . South o f Vancouver, the impact o f the W e s t e r l i e s l e s s e n s s i g n i f i c a n t l y as we near the P a c i f i c a n t i c y c l o n e r e g i o n where a i r movement r e s u l t s i n s t a b l e high p r e s s u r e a r e a s . Often i n summer, t h i s h i g h presure r e g i o n extends north to Vancouver. Often a high p r e s s u r e a n t i c y c l o n i c system w i l l s i t o f f the c o a s t " d e f l e c t i n g " o t h e r incoming a i r masses away from Vancouver. The r e s u l t i s the Vancouver area s i t s w i t h i n a high p r e s s u r e a i r mass e x p e r i e n c i n g " a i r mass" as opposed to " f r o n t a l " weather with c l e a r s k i e s a l l o w i n g s o l a r FIGURE 12: S c h e m a t i c i l l u s t r a t i o n of the f o r m a t i o n of c y c l o n e s ' and a n t i c y c l o n e s . (A) W e s t e r l i e s a re s t r o n g , p r e s s u r e systems have a p r e d o m i n a n t l y e a s t - w e s t o r i e n t a t i o n . L i t t l e n o r t h - s o u t h a i r mass e x c h a n g e . (B) and (C) J e t expands and i n c r e a s e s i n v e l o c i t y and u n d u l a t e s . (D) Complete b r e a k - u p and f r a g m e n t a t i o n of t h e z o n a l w e s t e r l i e s . F o r m a t i o n of c y c l o n e s and a n t i -cy l o n e s . S o u r c e : B a r r y and C h o r l e y , 1982 , p . 1 4 1 . 46 energy to reach the s u r f a c e . Temperatures could be q u i t e high d u r i n g the summer i f i t were not f o r the moderating e f f e c t o f the ocean. The "average" winter and summer c o n d i t i o n s t h a t have been d e s c r i b e d can both occur anytime of the year. Low p r e s s u r e d i s t u r b a n c e s i n summer are l e s s v i g o r o u s than i n winter, o f t e n with extended c l o u d cover and l i g h t e r winds. ( i i i ) A i r mass i n f l u e n c e ; A i r mass movements are an important f a c t o r i n Vancouver's c l i m a t e . There are f o u r major types of a i r masses c l a s s e d a c c o r d i n g to t h e i r area o f o r i g i n . Vancouver's c l i m a t e i s sometimes i n f l u e n c e d by two of these: the m o d i f i e d C o n t i n e n t a l A r c t i c and the m o d i f i e d Maritime T r o p i c a l . 3.5.7 Present C l i m a t i c I n f l u e n c e s and Model R e s u l t s The c l i m a t i c i n f l u e n c e s i n Vancouver c o u l d be s i g n i f i -c a n t l y a l t e r e d i f the r e s u l t s , suggested by the models of c l i m a t i c change, are r e a l i z e d . The r e s u l t s presented i n S e c t i o n 3.5.4 suggest the f o l l o w i n g s c e n a r i o f o r Vancouver's c l i m a t e : ( i ) The average s u r f a c e temperature would i n c r e a s e by approximately 3°C (see F i g u r e 10). Winters would warm more than summers. ( i i ) Due to i n c r e a s e d assymetry of the p o l e s , there would be a s h i f t i n the c l i m a t i c zones 200 km poleward. Due to the decreased temperature g r a d i e n t between the equator and the p o l e s , the s t r e n g t h of the W e s t e r l i e s would weaken. In w i n t e r , 47 the r e s u l t would be l e s s frequent c y c l o n i c d i s t u r b a n c e s . In summer, the e x t e n s i o n of the P a c i f i c a n t i c y c l o n i c regime c l o s e r to the Vancouver area would occur more o f t e n than a t p r e s e n t , c a u s i n g more high p r e s s u r e , c l e a r - s k y warm days. ( i i i ) A r c t i c warming and m e l t i n g o f the A r c t i c i c e and the i n c r e a s e i n moisture i n the A r c t i c due to i n c r e a s e d e v a p o r a t i o n would r e s u l t i n C o n t i n e n t a l A r c t i c a i r masses with much high e r moisture content as w e l l as high e r temperatures. Thus, although Vancouver would experience l e s s f requent c y c l o n i c d i s t u r b a n c e s and l e s s f r o n t a l a c t i v i t y , those f r o n t a l storms t h a t do occur would b r i n g more i n t e n s e p r e c i p i t a t i o n due to m o i s t e r a i r masses. ( i v ) The mountains and oceans would s t i l l have a g r e a t i n f l u e n c e on incoming a i r masses. The moisture content o f incoming Maritime T r o p i c a l a i r masses would be g r e a t e r than a t present because i n c r e a s e d temperatures would r e s u l t i n g r e a t e r e v a p o r a t i o n from the oceans. More p e r s i s t e n t a n t i c y c l o n e s o f f the c o a s t may prevent these a i r masses from reachi n g the Vancouver area i n the summer. (v) R a d i a t i o n fog would i n c r e a s e due to i n c r e a s e d calm c o n d i t i o n s and c l e a r s k i e s when a n t i - c y c l o n i c a i r masses dominate. T h i s type of fog i s e a s i l y d i s s i p a t e d i n the mornings by sun and a i r movement. G e n e r a l l y n o c t u r n a l c o o l i n g would not be s u f f i c i e n t f o r r a d i a t i o n fog to occur i n summer. More common may be a d v e c t i o n fog which c o u l d form more f r e q u e n t l y i n wint e r when a i r moving over the o f f s h o r e waters i n 48 the S t r a i t o f Georgia p i c k s up moisture and/or becomes s a t u r a t e d as i t begins to flow over the cooler- near shore waters. Advection fog would be more common because the ocean would be warmer than a t present, i n r e l a t i o n to the land s u r f a c e thus the a i r flowing over the ocean would be warmer. In a d d i t i o n , e v a p o r a t i o n from the warmer ocean would i n c r e a s e thus the incoming a i r masses would c o n t a i n more moi s t u r e . Because of the c o n t i n u a l flow of a i r over the ocean, a d v e c t i o n fogs can be q u i t e p e r s i s t e n t ; the sun's energy having l i t t l e e f f e c t on them. 3.5.8 Net R e s u l t : A S c e n a r i o f o r Vancouver's Climate The model r e s u l t s suggest the f o l l o w i n g s c e n a r i o f o r the c l i m a t e o f Vancouver as a r e s u l t o f a carbon d i o x i d e - i n d u c e d warming: 1 J ( i ) Winter: (a) Temperature - warmer. Average s u r f a c e a i r temperatures of approximately 5.5°C i n January as compared to present average of 2.5°C. (b) P r e c i p i t a t i o n - l e s s frequent p r e c i p i t a t i o n but more i n t e n s e when i t does occur. Probably more o v e r a l l . (c) Fog - i n c r e a s e d . More r a d i a t i o n fog d u r i n g (uncommon) a n t i - c y c l o n i c a c t i v i t y and more a d v e c t i o n fog. ( i i ) Summer: (a) Temperature - warmer. Average s u r f a c e a i r temperature of approximately 20°C i n J u l y as compared to pr e s e n t average of 17.3°C. (b) P r e c i p i t a t i o n - some i n c r e a s e due to m o i s t u r e -l a d e n a i r masses from over the ocean. (c) Fog - some i n c r e a s e . Perhaps a s l i g h t i n c r e a s e i n the amount of a d v e c t i o n fog. Figure 13 superimposes these changes i n temperature and p r e c i p i t a t i o n on e x i s t i n g c o n d i t i o n s . 3.6 P a l e o c l i m a t i c Evidence f o r S c e n a r i o Development 3.6.1 The method e x p l a i n e d T h i s method takes advantage of the temperature d a t a produced by c l i m a t e models by using the p r o j e c t e d temperature i n c r e a s e s as a s t a r t i n g p o i n t f o r a n a l y s i s . C l i m a t i c s c e n a r i o s are developed by l o o k i n g back i n time to p e r i o d s i n which there i s evidence t h a t the GAST was 2.5°C warmer, and by attempting to r e c o n s t r u c t p r e c i p i t a t i o n , atmospheric c i r c u l a t i o n and s o i l moisture c o n d i t i o n s d u r i n g those times. In t h i s way, an analogue i s developed f o r the c l i m a t e of the f u t u r e , i f a carbon d i o x i d e - i n d u c e d warming o c c u r s . Such warmer times are thought to have e x i s t e d 4,000 to 8,000 years ago d u r i n g the peak of the Holocene or A l t i t h e r m a l 5Q:, FIGURE 13: " C h a n g e s i n t e m p e r a t u r e and p r e c i p i t a t i o n as s u g g e s t e d by the c l i m a t e m o d e l s . Based on F i g u r e 10. 51 p e r i o d ( K e l l o g g , 1978) and a l s o approximately 120,000 years ago (Flohn, 1982). Evidence from these p e r i o d s such as t r e e r i n g s , i c e core i n t e r p r e t a t i o n s , p o l l e n data and f o s s i l s can g i v e some i d e a o f pa s t c l i m a t i c c o n d i t i o n s . The i c e core and f o s s i l a n a l y s e s are p a r t i c u l a r l y u s e f u l f o r proving t h a t temperatures were h i g h e r than p r e s e n t : the r a t i o o f d i f f e r e n t i s o t o p e s of oxygen (oxygen-16 and oxygen-18) present i n a i r and water i s dependent on temperature. Some of t h i s oxygen ge t s trapped i n i c e or f o s s i l s and the r a t i o i n d i c a t e s average temperatures. Combining t h i s knowledge with the determined age of the i c e or f o s s i l can g i v e a good i n d i c a t i o n o f past temperatures ( G r i b b i n , 1975). 3.6.2 L i m i t a t i o n s of P a l e o c l i m a t e evidence The use of r e c o n s t r u c t e d p a s t c l i m a t e s as analogues f o r c l i m a t i c c o n d i t i o n s under a carbon d i o x i d e - i n d u c e d warming has been c r i t i c i z e d because: ( i ) the boundary c o n d i t i o n s i n the past such as d i s t r i b u t i o n of v e g e t a t i o n or o t h e r s u r f a c e p r o p e r t i e s may have been q u i t e d i f f e r e n t (IIASA, 1981). In a d d i t i o n , human a c t i v i t i e s p a r t i c u l a r l y d e f o r e s t a t i o n have c o n t r i b u t e d to the very d i f f e r e n t c o n d i t i o n s t h a t e x i s t today. As a r e s u l t , a temperature i n c r e a s e a t present c o u l d have v e r y d i f f e r e n t r e p e r c u s s i o n s than i n the past (Wigley et a l . , 1982). ( i i ) the f a c t o r o r f a c t o r s t h a t l e d to an i n c r e a s e i n GAST i n the past were probably not due to i n c r e a s e d atmospheric 52 carbon d i o x i d e ( P i t t o c k and S a l i n g e r , 1982). Climate changes due to d i f f e r e n t f a c t o r s may vary s e a s o n a l l y , s p a t i a l l y , t e m p o r a l l y , o r i n magnitude. ( i i i ) the warming, p a r t i c u l a r l y d u r i n g the Holocene p e r i o d was " t i m e - t r a n s g r e s s i v e " o r i n other words, i t i s b e l i e v e d peak warming d i d not occur a t the same time i n a l l p l a c e s ( W i l l i a m s , 1980). The order i n which areas warmed c o u l d s i g n i f i c a n t l y a f f e c t atmospheric c i r c u l a t i o n p a t t e r n s which i n tu r n a f f e c t s c l i m a t e . ( i v ) there i s a l a c k o f data about c o n d i t i o n s i n the p a s t . Data are o f t e n i n f e r r e d i n d i r e c t l y from o t h e r evidence (e.g., p r e c i p i t a t i o n i s i n f e r r e d from ve g e t a t i o n ) and are t h e r e -f o r e q u a l i t a t i v e (e.g., wetter o r d r y e r than p r e s e n t ) . 3.6.3 P a l e o c l i m a t e evidence from the l i t e r a t u r e Due to the above l i m i t a t i o n s , c l i m a t e c o n d i t i o n s d u r i n g p r e v i o u s warmer p e r i o d s can not be accepted as exact r e p r e s e n t a t i o n s o f what might occur under a carbon d i o x i d e -induced warming. N e v e r t h e l e s s , the use of p a l e o c l i m a t i c evidence as an analogue has some advantages. Most important, t h i s method can g i v e us some idea o f the r e g i o n a l c o n d i t i o n s that cannot be a t t a i n e d through the use of c l i m a t e models. An encouraging p i e c e o f i n f o r m a t i o n , l e a r n e d from m a n i p u l a t i o n o f the c l i m a t e models, i s t h a t v a r i o u s warming i n f l u e n c e s (e.g., i n c r e a s e d atmospheric carbon d i o x i d e o r a change i n the s o l a r c o n s t a n t ) , have r e s u l t e d i n s i m i l a r p a t t e r n s of c l i m a t e change (Wigley e t . a l . , 1980). T h e r e f o r e , even though past warmer p e r i o d s were probably not due to carbon d i o x i d e perhaps s i m i l a r changes can be a n t i c i p a t e d . Flohn, (1982), argues p a l e o c l i m a t i c analogues have one over-r i d i n g advantage. They r e p r e s e n t r e a l i s t i c s o l u t i o n s of the complete s e t of equations t h a t o n l y nature can s o l v e , o n - l i n e and i n i t s own time (p.146) although he does r e c o g n i z e the problem of changing boundary c o n d i t i o n s . Flohn has examined a number of time p e r i o d s i n c l u d i n g the era of approximately 120,000 years ago when the g l o b a l average s u r f a c e temperature i s b e l i e v e d to have been 2.5°C warmer than p r e s e n t . Based on p a l e o c l i m a t i c evidence from t h i s time, Flohn puts together an "admittedly s p e c u l a t i v e y e t c a r e f u l l y c a l c u l a t e d " (IIASA, 1981, pp. i i i - i v ) s c e n a r i o of p o s s i b l e c o n d i t i o n s i f a 2.5°C warming were to occur again: A r c t i c d r i f t i c e would disappear completely but t h i c k A n t a r c t i c i c e would remain, r e s u l t i n g i n an i n c r e a s i n g imbalance between the two p o l e s . As a r e s u l t , i n the northern hemisphere the s u b t r o p i c a l b e l t would s h i f t to the north 100-200 km i n summer and 800 km or more i n w i n t e r . Areas of drought would extend northwest i n North America. Flohn makes an "educated guess" that such changes would l e a d to the l a t i t u d i n a l changes i n temperature and p r e c i p i t a t i o n i l l u s t r a t e d i n F i g u r e 14. K e l l o g g who b e l i e v e s "using the r e a l e a r t h f o r a model i s at l e a s t as good, and probably b e t t e r than, the t h e o r e t i c a l 54 FIGURE 14: P r o j e c t e d l a t i t u d i n a l v a r i a t i o n i n annual s u r f a c e t e m p e r a t u r e s and annual p r e c i p i t a t i o n . Note the Vancouver are at 49°N c o u l d be a p p r o x i m a t e l y 4° to 7°C warmer and p r e c i p i t a t i o n c o u l d i n c r e a s e by as much as 10%. Source: F l o h n , 1982, p. 166. numerical models" ( i n Bernard, 1980, p. 31), was the f i r s t to suggest the use of p a l e o c l i m a t i c evidence i n r e l a t i o n t o a carbon d i o x i d e - i n d u c e d warming. He l o o k s a t the peak of the Holocene or A l t i t h e r m a l p e r i o d , 4,000 to 8,000 years ago and has gathered more than 100 r e f e r e n c e s d e a l i n g with c o n d i t i o n s d u r i n g t h i s time i n order to develop a map i l l u s t r a t i n g what areas o f the e a r t h were wetter or d r i e r than a t presen t (see Figure 15). K e l l o g g c a u t i o n s t h a t the i n f o r m a t i o n on which t h i s map i s based i s p a r t i a l nor should i t be taken as a l i t e r a l i n d i c a t i o n of what w i l l happen i f the e a r t h i s warmed again ( K e l l o g g , 1979). S i m i l a r l y , K e l l o g g and Schware (1981) have gathered s o i l m oisture i n f o r m a t i o n to compile a map i l l u s t r a t i n g s o i l s t h a t were wetter or d r i e r than now (see Figure 16). T h i s map, however, i s not based s o l e l y on p a l e o c l i m a t i c evidence but a l s o on comparisions o f r e c e n t warm and c o l d years and on a c l i m a t e model experiment. 3.6.4 P a l e o c l i m a t i c evidence i n the Vancouver r e g i o n A comprehensive a n a l y s i s of c o n d i t i o n s i n B r i t i s h Columbia during the Holocene p e r i o d has not been undertaken (Ryder, 1978). Evidence of c o n d i t i o n s d u r i n g t h i s warmer e r a must be taken from s t u d i e s by Flohn (1981), K e l l o g g (1979) and Ke l l o g g and Schware (1981). Flohn's study ( F i g u r e 14) i n d i c a t e s the l a t i t u d i n a l zone i n which Vancouver i s l o c a t e d c o u l d have an annual s u r f a c e temperature 4°C to 7°C warmer and r e c e i v e as much as 10% more 56 180 90N|_i I I I I I I I I I 40N 40S 90W ' ' ' I l i i 11 i i 11 i n i n i i i i i i i 11 i i i 11 i 0 90E !S° 11 I I T 11 i i i I I I I i n n |i i T T I rni i J90N WETTER j / , l o t . in pS ; / period t-,- i ; ;w£TTEf f - , ; ; . ? 90S h i L 1 1 1 1 1 1 1 1 1 i n 11 • 11 in i n l i 111 • i 1111 111 • i i • | M 11 111 ) 1 1 t 1 11 1 1 n 1 1 1 1 1 1 '~J90S 40N 40S ISO 90W 90E 180 FIGURE 15 A n approximate d e p i c t i o n of the r e g i o n s i n the world which were w e t t e r or d r i e r than the pr e s e n t d u r i n g the A l t i t h e r m a l P e r i o d about 4000 t o 8000 years ago. The blank areas on the map are not n e c e s s a r i l y r e g i o n s where t h e r e was no change but where infor-m-ation i s in c o m p l e t e . Source: K e l l o g g , 1979 , p.83. 57 90Nn 40NF-40SF 440N W h - . - . , WETTEft;*^,.,"V Wetter than now Drier than now mm v vv?f'v. , WETTfcft » i:v-:.- >;;x: : :y 340S 180 90W 0 90E iil90S 180 FIGURE 16"A s c e n a r i o of p o s s i b l e s o i l m o i s t u r e p a t t e r n s on a 'warmer e a r t h . Where two or more sources agree on the d i r e c t i o n of change, the area of agreement i s i n d i c a t e d w i t h a dashed l i n e and a l a b e l . Source: K e l l o g g and Schware, 1981, p.49. 58 p r e c i p i t a t i o n than a t p r e s e n t . K e l l o g g (1979) suggests t h a t the r e g i o n c o n t a i n i n g the study area was wetter than a t presen t d u r i n g the Holocene p e r i o d ( F i g u r e 15). S i m i l a r l y , the study by K e l l o g g and Schware (1981) i n d i c a t e s the Vancouver r e g i o n had wetter s o i l moisture c o n d i t i o n s d u r i n g the Holocene p e r i o d ( F i g u r e 16). No study of the s e a s o n a l i t y o f these changes has been undertaken. 3.6.5 C l i m a t i c Scenario f o r Vancouver based on P a l e o c l i m a t i c Evidence Using p a l e o c l i m a t i c evidence the f o l l o w i n g s c e n a r i o f o r Vancouver, ( i f the GAST i n c r e a s e s by 2.5°C) i s developed: ( i ) The mean annual s u r f a c e temperature i n the Vancouver area would be 13.8°C to 16.8°C as compared to the present mean o f 9.8°C. ( i i ) P r e c i p i t a t i o n would i n c r e a s e by as much as 112 mm per year. (The l i k e l i h o o d of a zero i n c r e a s e i n p r e c i p i t a t i o n t h a t Flohn p r o j e c t s c o u l d occur seems u n l i k e l y g i v e n the evidence to the c o n t r a r y by K e l l o g g (1979) and K e l l o g g and Schware (1981)). ( i i i ) S o i l c o n d i t i o n s would be wetter. T h i s i n d i c a t e s t h a t an i n c r e a s e i n p r e c i p i t a t i o n would not be o f f s e t by an in c r e a s e i n e v a p o r a t i o n . 59 3.7 The Use of Recent Recorded Data 3.7.1 The method e x p l a i n e d A t h i r d method used to determine the impacts of g l o b a l warming on a r e g i o n a l s c a l e i s v e r y s i m i l a r t o method 2: evidence from the p a s t i s again used to develop an analogue f o r c o n d i t i o n s i n the f u t u r e . The d i f f e r e n c e i s t h a t r e c e n t recorded data are used. Temperature data from the r e c e n t past are compared with p r e c i p i t a t i o n data to see i f any p a t t e r n can be d e t e c t e d . These p a t t e r n s of v a r i a t i o n i n p r e c i p i t a t i o n with short-term temperature changes are assumed to be the same p a t t e r n s t h a t w i l l occur with l o n g e r term temperature changes. Hypotheses can be made and t e s t e d : Is there more p r e c i p i t a t i o n d u r i n g warm years? Is there more p r e c i p i t a t i o n d u r i n g warm summers? Warm winters? I f there i s a r e l a t i o n s h i p between temperature and p r e c i p i t a t i o n , how strong i s i t ? If p r e c i p i t a t i o n v a r i e s with s l i g h t warmings, how might i t v a r y with a 2.5°C i n c r e a s e i n GAST? 3.7.2 L i m i t a t i o n s of r e c e n t recorded data The use of r e c e n t recorded data i n the formation o f c l i m a t e s c e n a r i o s shares some of the same l i m i t a t i o n s as does the use of p a l e o c l i m a t i c evidence. F i r s t , the boundary c o n d i t i o n s i n an a c t u a l g l o b a l warming may v a r y . Second, r e c e n t warm years or decades are not due to e l e v a t e d l e v e l s of carbon d i o x i d e during those years (Wigley e t a l . , 1980). T h i r d , the r e l a t i o n s h i p between temperature and p r e c i p i t a t i o n can not be 60 assumed to be a l i n e a r one. For example, because p r e c i p i t a t i o n may i n c r e a s e by 200 mm with a 1°C warming does not mean a 400 mm i n c r e a s e i n p r e c i p i t a t i o n w i l l n e c e s s a r i l y o c c u r with a 2°C warming. In a d d i t i o n , an a c t u a l g l o b a l warming would be a s u s t a i n e d s i t u a t i o n with some impacts not showing up f o r a number of y e a r s . In p a r t i c u l a r , o c e a n i c responses to i n c r e a s i n g temperatures may take many years to occur as the ocean absorbs heat more s l o w l y than the l a n d . For t h i s reason, a n a l y s i s of "warm" decades r a t h e r than i n d i v i d u a l "warm" years may y i e l d more a c c u r a t e r e s u l t s (CG^/Climate Review Panel, 1982). Despite these l i m i t a t i o n s , the study of r e c e n t recorded d a t a can p r o v i d e u s e f u l i n s i g h t i n t o c l i m a t i c responses under v a r i o u s c o n d i t i o n s . 3.7.3 Survey o f the l i t e r a t u r e A number of r e s e a r c h e r s have analysed r e c e n t recorded data i n an attempt to understand what c l i m a t i c c o n d i t i o n s may be l i k e i n an era of carbon d i o x i d e - i n d u c e d warming ( P i t t o c k and S a l i n g e r , 1982; McGuirk, 1982; Namias, 1980; Lough e t a l . , 1983 and Wigley et a l . , 1980; Bernard, 1980; W i l l i a m s , 1980). Although Wigley e t a l . (1980), Bernard (1980) and W i l l i a m s (1980) examine r e c e n t recorded data along the P a c i f i c Coast of North America, no a n a l y s i s has been done s p e c i f i c a l l y f o r the 61 Vancouver a r e a . 1 However, some id e a o f c o n d i t i o n s i n the Vancouver area can be determined from the above three s t u d i e s . Wigley e t a l . (1980) use a composite o f a number of warm years i n r e c e n t h i s t o r y , w i t h i n the Northern Hemisphere, as an analogue f o r a warmer world. The f i v e warmest years were chosen but not on the b a s i s o f whether they were warmer than the Northern Hemispheric mean annual temperature. Rather, the mean annual temperatures w i t h i n l a t i t u d e s 65°N t o 80°N were examined and the f i v e warmest years i n these h i g h e r a l t i t u d e s chosen. Subsequently, data f o r these years i n the r e s t of the Northern Hemisphere were examined. T h i s method was chosen because the numerical models suggest t h a t warming would be most s i g n i f i c a n t i n the high l a t i t u d e s thus Wigley e t . a l . b e l i e v e d i t was important t o look a t how temperature and p r e c i p i t a t i o n would va r y throughout the hemisphere, d u r i n g years i n which temperatures were warmest i n the high e r l a t i t u d e s . In order to get an id e a o f the changes t h a t accompany "warm" yea r s , " c o l d " years were a l s o examined. 1937, 1938, 1943, 1944 and 1953 were found to be on average 1.6°C warmer than c o l d years (1964, 1965, 1968, 1972) i n the high e r T~. An a n a l y s i s o f re c e n t recorded data i n the Vancouver area was b e l i e v e d to be a l a r g e undertaking t h a t would y i e l d i n s u f f i c i e n t r e t u r n s f o r the e f f o r t r e q u i r e d . S u i t a b l e data are not r e a d i l y a v a i l a b l e and i t was a l s o b e l i e v e d t h a t r e s u l t s o b t ained by ob s e r v i n g p r e c i p i t a t i o n and temperature changes over the s h o r t - t e r m c o u l d not e a s i l y be used to make statements about what may happen with long-term c l i m a t i c change. However the a n a l y s i s would be i n t e r e s t i n g and co u l d g i v e some i n d i c a t i o n of the p o s s i b l e d i r e c t i o n and magnitude of change. 62 l a t i t u d e s . In the Northern Hemisphere as a whole, these "warm" years were on average, 0.6°C warmer than " c o l d " y e a r s . F i g u r e 17 i l l u s t r a t e s how temperature v a r i e d i n the Northern Hemisphere from " c o l d " t o "warm" ye a r s . P r e c i p i t a t i o n p a t t e r n s i n the northern hemisphere were a l s o examined and the change i n p r e c i p i t a t i o n from " c o l d " to "warm" years was mapped (see F i g u r e 18). Examination of F i g u r e 17 shows the mean annual s u r f a c e temperature i n the Vancouver a r e a , d u r i n g "warm" years i n the h i g h e r l a t i t u d e s , was roughly 1°C warmer than d u r i n g the c o l d y e a r s . T h e r e f o r e , when hi g h e r l a t i t u d e temperatures were p a r t i c u l a r l y warm, the Vancouver r e g i o n was s i g n i f i c a n t l y warmer. Figure 18 shows an i n c r e a s e i n p r e c i p i t a t i o n i n the Vancouver r e g i o n d u r i n g the same "warm" y e a r s . I f these changes i n p r e c i p i t a t i o n and temperature occ u r r e d with o n l y a s l i g h t warming i n the h i g h e r l a t i t u d e s , much g r e a t e r i n c r e a s e s c o u l d occur with an i n c r e a s e of 10° to 12°C i n the h i g h e r l a t i t u d e s . A second study by Bernard (1980) a l s o uses r e c e n t recorded data as an analogue f o r a warmer e a r t h . Bernard l o o k s a t the P a c i f i c Northwest of North America and uses the 1930's as a c l i m a t e analogue f o r the i n i t i a l decade of a carbon d i o x i d e -induced warming, when he b e l i e v e s the mean s u r f a c e temperature w i l l be 1°F (approximately 0.5°C) warmer than p r e s e n t . According to Bernard the 1930's "marked the peak of the most re c e n t g l o b a l warming," (p. 32) when average temperatures were about 1°F warmer than at p r e s e n t . Bernard compares the averages 63 I ] Insufficient 1— 1 data FIGURE 17! Mean annual surface temperature changes from cold to warm years. The corresponding change i n the hemispheric mean temperature i s 0.6 C. Note that during "warm" years i n the higher l a t i t u d e s , the Vancouver area was roughly 1 C warmer than during .cold years. SOURCE: Wigley, Jones and K e l l y , 1980, p. 18. 64 FIGURE 18: Mean annual p r e c i p i t a t i o n changes from c o l d t o warm y e a r s . Note t h a t d u r i n g "warm" years i n the h i g h e r • l a t i t u d e s , the Vancouver area e x p e r i e n c e d an i n c r e a s e i n p r e c i p i t a t i o n . Source: W i g l e y , Jones and K e l l y , 1980, p.20. of temperature and p r e c i p i t a t i o n f o r the 1930 to 1939 decade with the 1941 to 1970 normals to "get a f e e l i n g f o r what the i n i t i a l stages of ... warming ... may be l i k e " (p. 7 1 ) . Although the a n a l y s i s i s v e r y s u p e r f i c i a l , much of the P a c i f i c c oast was shown to be s l i g h t l y c o o l e r d u r i n g the 1930-39 decade. Although there were g r e a t annual f l u c t u a t i o n s i n p r e c i p i t a t i o n -the wettest year on r e c o r d was f o l l o w e d by the d r i e s t - o v e r - a l l p r e c i p i t a t i o n was unchanged. Few c o n c l u s i o n s can be drawn from Bernard's a n a l y s i s but h i s study does suggest t h a t a t l e a s t f o r the i n i t i a l decade of warming, p r e c i p i t a t i o n c o u l d f l u c t u a t e d r a m a t i c a l l y . A t h i r d study by W i l l i a m s (1980) examines temperature and p r e c i p i t a t i o n anomalies i n the n o r t h e r n hemisphere, f o r seasons w i t h i n the l a s t 70 years when the A r c t i c was warmer than n o r m a l . 1 Warm A r c t i c seasons were chosen because computer models have shown the A r c t i c i s more s e n s i t i v e to c l i m a t e changes. The ten "warmest A r c t i c w i n t e r s " and the ten "warmest A r c t i c summers" were determined by examining d e v i a t i o n s from the mean temperatures a t s t a t i o n s n o r t h of 65°N d u r i n g the l a s t 70 y e a r s . Temperature and p r e c i p i t a t i o n d ata f o r s t a t i o n s i n o t h e r p a r t s of the Northern Hemisphere were then examined d u r i n g the 1. Climate normals are the mean c l i m a t e s t a t i s t i c s f o r a r e c e n t 30 year p e r i o d . At p r e s e n t , the 30 year p e r i o d used i s 1951 to 1980. In 1990, t h i s time p e r i o d w i l l advance ten years (1961- 199 0 ) . T h i s system has been adopted by the World M e t e r e o l o g i c a l O r g a n i z a t i o n . 66 same 70 years. F i r s t , the mean temperature and p r e c i p i t a t i o n were determined f o r the years when the A r c t i c experienced the ten warmest summers and w i n t e r s . Second, the "long-term" mean temperature and p r e c i p i t a t i o n were determined f o r the remaining years d u r i n g the 70 year p e r i o d . Temperature and p r e c i p i t a t i o n anomalies were then c a l c u l a t e d by determining the d i f f e r e n c e between these two means. In F i g u r e 19 the shaded areas i n d i c a t e areas where the anomaly was l e s s than zero during w i n t e r . The i s o l i n e t h a t passes through the Vancouver area (1°C) i n d i c a t e s t h a t Vancouver w i n t e r s , during the ten years when the A r c t i c experienced the warmest winter temperatures, were a l s o warmer than "normal" by 1°C. ( V i c t o r i a i s a c t u a l l y the c l o s e s t s t a t i o n examined by W i l l i a m s and shows a 0.69°C anomaly; Spokane has an anomaly of 1. 2°C.) F i g u r e 20 i l l u s t r a t e s the temperature anomalies d u r i n g summer months. The Vancouver area shows an anomaly of between 0°C and 1°C i n d i c a t i n g t h a t Vancouver summers, d u r i n g the ten years when the A r c t i c experienced the warmest summer temperatures, were a l s o warmer than "normal" by 0°C to 1°C. F i g u r e s 21 and 22 i l l u s t r a t e p r e c i p i t a t i o n c o n d i t i o n s i n North America dur i n g the ten warmest A r c t i c w i n t e r s and ten warmest A r c t i c summers r e s p e c t i v e l y . The f i g u r e s i n d i c a t e Vancouver p r e c i p i t a t i o n i n c r e a s e d , both i n winter and summer, during the years when the A r c t i c experienced the warmest winters 67 180* .0 FIGURE 19: D i f f e r e n c e s i n s u r f a c e temperature between the mean of the 10 warmest A r c t i c w i n t e r s and the long-term mean of the rem a i n i n g w i n t e r s i n the 1900-1969 p e r i o d . Hatched areas show n e g a t i v e a n o m a l i e s . Note t h a t when the A r c t i c e x p e r i e n c e d the warmest w i n t e r t e m p e r a t u r e s , the Vancouver area was a l s o warmer than "normal" by 1°C. Source: W i l l i a m s , 1980, p.255. 68, 180* .0 FIGURE 20: Dlfffffe-nentres i n s u r f a c e temperature between the mean of the 10 warmest A r c t i c summers and the long-term mean of the rem a i n i n g summers i n the 1900- 1969 p e r i o d . Hatched areas show n e g a t i v e a n o m a l i e s . Note t h a t when,the A r c t i c e x p e r i e n c e d the warmest summer t e m p e r a t u r e s , the Vancouver area a l s o e x p e r i e n c e d warmer summers. Source: W i l l i a m s , 1980, p.259. FIGURE 21: D i f f e r e n c e s i n p r e c i p i t a t i o n i n North America between the mean of the 10 warmest A r c t i c w i n t e r s and the long-term mean of the rem a i n i n g w i n t e r s i n the 1900-1969 p e r i o d . Shading i n d i c a t e s where p r e c i p i t a t i o n d e c r e a s e d . Note t h a t the Vancouver area e x p e r i e n c e d i n c r e a s e d p r e c i p i t a t i o n d u r i n g the p e r i o d when the A r c t i c e x p e r i e n c e d i t s t e n ^ warmest w i n t e r s . Source: W i l l i a m s , 1980, p.262. 70 FIGURE 22: D i f f e r e n c e s i n p r e c i p i t a t i o n i n North America between the mean of the 10 warmest A r c t i c summers and the long-term mean of the re m a i n i n g summers i n the 1900- 1969 p e r i o d . Shading i n d i c a t e s where p r e c i p i t a t i o n d e c r e a s e d . Note t h a t the Vancouver area e x p e r i e n c e d i n c r e a s e d p r e c i p i t a t i o n d u r i n g the p e r i o d when the A r c t i c e x p e r i e n c e d i t s ten warmest summers. Source: W i l l i a m s , 1980, p.263. 71 and summer. However, Wi l l i a m s found t h a t the d i f f e r e n c e s i n p r e c i p i t a t i o n were onl y s t a t i s t i c a l l y s i g n i f i c a n t i n summer. 3.7.4 A C l i m a t i c S c e n a r i o f o r Vancouver based on Analyses of Recent Recorded Data The three s t u d i e s by Wigley e t a l . (1980), Bernard (1980) and W i l l i a m s (1980) suggest the f o l l o w i n g s c e n a r i o f o r Vancouver i f the GAST i n c r e a s e s by 2.5°C: ( i ) Vancouver would be warmer both i n winter and summer than a t pres e n t ; ( i i ) P r e c i p i t a t i o n would i n c r e a s e p a r t i c u l a r l y i n summer; ( i i i ) At l e a s t during the i n i t i a l decade of warming, p r e c i p i t a t i o n could f l u c t u a t e d r a m a t i c a l l y . 3.8 Summary of C l i m a t i c S c e n a r i o s F i g u r e 23 i l l u s t r a t e s the r e s u l t s o f the three methods of s c e n a r i o development. Due to the l i m i t a t i o n s of g l o b a l c i r c u l a t i o n models and the p a u c i t y o f l i t e r a t u r e d e a l i n g with p a l e o c l i m a t i c evidence o r r e c e n t recorded data i n Vancouver, the s c e n a r i o s are incomplete and l a c k d e t a i l . However, the three s c e n a r i o s y i e l d s i m i l a r r e s u l t s : a l l p o i n t t o a warmer c l i m a t e with i n c r e a s e d p r e c i p i t a t i o n . Because the three methods y i e l d s i m i l a r r e s u l t s and none of the methods p r o v i d e s a d e t a i l e d c l i m a t i c s c e n a r i o , the three s c e n a r i o s have been grouped i n t o one (see F i g u r e 24). Although Wilson (1978) suggests a t l e a s t f o u r s c e n a r i o s be developed, the Figure 23: Summary of Scenarios WINTER SUMMER CLIMATE METHOD Temperature Precip. Fog Soil Mol st ure Temperature Precip. Fog Soil Moisture COMPUTER MODELLING Warmer: Average surface temperatures approx. 5.5°C in January (compared to present average of 2.5°C). Slight increase; less frequent storms but more intense. Increased incidences of advection fog. No indication. Warmer: Average surface temperature of approx. 20°C in July (compared to present average of 17.3°C). Some increase. Some increase. No. indicati on. PALEOCLIMATIC EVIDENCE Warmer: Average annual surface temp, of 13.8°C to 16.8°C (compared to present aver, of 9.8°C). Increased by as much as 10% per year. An Increase of approx. ?0mn in January. No indication. Molster. Warmer: Average annual surface temper, of 13.8°C to 16.8°C (compared to present aver, of 9.8°C). Increased by as much as 10% per year. Increase of approx. 4mm in July. No Indication. Moi ster. RECENT RECORDED DATA Warmer. Some increase. No indication. No. Indication. Warmer. Increase parti c-ularly in summer. No indicati on. No. indication. --4 Figure 24 The Scenario of Vancouver's Climate with a Carbon Dioxide-Induced Global Warming ( f u l l effects f e l t by approximately the year 2050) WINTER SUMMER TEMPERATURE Warmer: Average annual surface temperature of 13-15°C, compared to 9.8°C at present. January mean temperature of approximately 5.5°C, compared to present mean of 2.5°C. Warmer: Average annual surface temperature of 13-15°C, compared to 9.8°C at present. July mean temperature of approximately 20°C, compared to present mean of 17.3°C. PRECIPITATION Increased by as much as 10% per year. An increase by as much as 20mm in January. Less frequent storms but more intense. Increased by as much as 10% per year. An increase by as much as 4mm in July. FOG Increased incidences of advection fog. Some increase but most in winter. SOIL MOISTURE Moister. Moister. 74 l i m i t a t i o n s o f the methods used t o d e v e l o p s c e n a r i o s make t h i s d i f f i c u l t . 75 CHAPTER 4 IMPLICATIONS OF THE SCENARIOS Chapter 4 examines the s c e n a r i o , developed i n the p r e -ceeding chapter, i n terms of the environmental, s o c i a l and economic i m p l i c a t i o n s f o r (1) a g r i c u l t u r e , (2) f l o o d i n g , (3) water supply, and (4) human s e t t l e m e n t . For each of the above a f f e c t e d a c t i v i t i e s the probable extent and magnitude of change i s d e s c r i b e d . As w e l l , the frequency, p r o b a b i l i t y , p e r s i s t e n c e and/or d u r a t i o n o f the impacts i s i d e n t i f i e d where p o s s i b l e . The impacts are a l s o e v a l u a t e d t o determine i f they are b e n e f i c i a l o r harmful to s o c i e t y . G e n e r a l l y the i m p l i c a t i o n s f o r each a c t i v i t y are examined s e p a r a t e l y but there are obvious i n t e r r e l a t i o n s between the a c t i v i t i e s . In p a r t i c u l a r , the i m p l i c a t i o n s f o r human se t t l e m e n t are c l o s e l y r e l a t e d to the i m p l i c a t i o n s f o r f l o o d i n g , water supply and a g r i c u l t u r e . There may be many oth e r impacts such as the e f f e c t s on sewage d i s p o s a l , the water d i s t r i b u t i o n system, t r a n s p o r t a t i o n , the f o r e s t r y i n d u s t r y , f i s h e r i e s and w i l d l i f e , t h a t are not examined due to time c o n s t r a i n t s or l a c k of i n f o r m a t i o n on p o s s i b l e e f f e c t s . 4.1 I m p l i c a t i o n s f o r A g r i c u l t u r e S e c t i o n 4.1.1 w i l l d e a l with the i m p l i c a t i o n s o f a carbon d i o x i d e - i n d u c e d warming on a g r i c u l t u r e i n g e n e r a l ; 76 S e c t i o n 4.1.2 w i l l examine the s p e c i f i c i m p l i c a t i o n s f o r a g r i c u l t u r e i n the Vancouver r e g i o n of the s c e n a r i o developed i n Chapter 3. 4.1.1 I m p l i c a t i o n s f o r a g r i c u l t u r e i n g e n e r a l ( i ) Increased p r o d u c t i v i t y - In g e n e r a l , i n c r e a s e d atmospheric carbon d i o x i d e would b e n e f i t a l l p l a n t s because the d r i v i n g f o r c e behind p h o t o s y n t h e s i s - the carbon d i o x i d e g r a d i e n t between the atmosphere and the l e a f of a p l a n t - would be i n c r e a s e d . However, some p l a n t s would b e n e f i t more than o t h e r s i n a carbon d i o x i d e e n r i c h e d environment due to d i f f e r i n g p h o t o s y n t h e t i c mechanisms (Rosenberg, 1981; Moss, 1975). These mechanisms d i v i d e p l a n t s i n t o three groups: C3, C4 or CAM p l a n t s . In the Vancouver r e g i o n most p l a n t s are of the C3 v a r i e t y , C4 p l a n t s are more commonly t r o p i c a l and CAM p l a n t s are uncommon. Most of the world's food crops are C3; o n l y c o r n , sorghum and sugarcane are important C4 c r o p s . F i g u r e 25 l i s t s C3 and C4 p l a n t s commonly found i n the Vancouver area. F i g u r e 26 i l l u s t r a t e s the p r o d u c t i o n by l a t i t u d e o f C3 and C4 p l a n t s . R e s p i r a t i o n i n both C3 and C4 p l a n t s o c c u r s e s s e n t i a l l y by the same b i o c h e m i c a l pathway c a l l e d "dark r e s p i r a t i o n " , however C3 v a r i e t i e s have an a d d i t i o n a l r e s p i r a t o r y mechanism c a l l e d p h o t o r e s p i r a t i o n . Because a l l p l a n t s consume some photosynthate d u r i n g r e s p i r a t i o n , the f a c t t h a t C3 p l a n t s have an a d d i t i o n a l r e s p i r a t o r y mechanism i s a disadvantage: rice (Oryza saliva L.) alta fescue (Festuca arundinacea Schreb.) blucgrass (Poa pratensis L.) oats (Avena saliva L.) * crested wheatgrass (Agropyron desertontm (Fisch.) Schult.) barley (Hordeum vulgare L.) * rye (Secale cereale L.) * wheat {Triticum aestivum L.) * sugarbect (Beta vulgaris L.) spearscale (Atriplex patula L.) bean (Phaseolus vulgaris L.) * soybean (Glycine max (L.) Mcrr.) alfalfa (Medicago saliva L.) * cotton (Gossypiutn hirsutum L.) potato (Solatium tuberosum L.) * tomato (l.ycopersicon esculentum Mill.) ^  sunflower (Helianthus annuus L.) purple lovegrass (eragrostis spectabilis (Pursh) Steud.) Rhodes grass (CMoris gayana Kunth) smooth cordgrass (Spartina alterniflora Loisel) pearl millet (Pennisetum glaucum (L.) R. Br.) sugar-cane (Saccharum officinarum L.) sorghum (Sorghum bicolor (L.) Moench) maize (Zca mays L.) * red orachc (Atriplex rosea L.) FIGURE 25: C 3 a n d C 4 p l a n t s . A s t e r i s k s i n d i c a t e commonly found i n the Vancouver a r e a . Source: Rosenberg, 1981, p.266. p l a n t s LATITUDE FIGURE 26: SOURCE: A n n u a l p r o d u c t i o n o f C3 a n d . C ^ p l a n t s b y l a t i t u d e . R o s e n b e r g , 1 9 8 1 , p . 2 6 7 . 79 p h o t o s y n t h e t i c g a i n minus r e s p i r a t o r y l o s s w i l l always be lower' i n C3 than i n C4 p l a n t s . However, i n a carbon d i o x i d e e n r i c h e d atmosphere there i s some evidence t h a t p h o t o r e s p i r a t i o n w i l l be suppressed to some extent (Rosenberg, 1981). In a d d i t i o n , p l a n t s p o s s e s s i n g p h o t o r e s p i r a t i o n have been shown to i n c r e a s e p h o t o s y n t h e t i c a c t i v i t y i n a carbon d i o x i d e e n r i c h e d atmosphere. Most experiments have taken p l a c e i n greenhouses because carbon d i o x i d e r e l e a s e d onto f i e l d s r a p i d l y mixes i n t o the atmosphere. However, greenhouse experiments have shown t h a t the c o n c e n t r a t i o n of carbon d i o x i d e i n the l e a v e s of p l a n t s having p h o t o r e s p i r a t i o n i s g r e a t e r than i n C4 p l a n t s and t h e r e f o r e the a t m o s p h e r i c - l e a f g r a d i e n t i s g e n e r a l l y s m a l l e r . Increased atmospheric carbon d i o x i d e would, of course, i n c r e a s e t h i s g r a d i e n t thus i n c r e a s i n g the d r i v i n g f o r c e and u l t i m a t e l y i n c r e a s i n g p h o t o s y n t h e s i s . F i g u r e 27 i l l u s t r a t e s the change i n f o u r p l a n t s grown a t e l e v a t e d carbon d i o x i d e l e v e l s . Note the f i r s t three p l a n t s ( c o t t o n , soybeans and sunflowers) are C3 p l a n t s and the f o u r t h (sorghum) i s a C4 p l a n t . T h i s experiment i l l u s t r a t e s the p o s s i b l e i n c r e a s e i n p r o d u c t i v i t y with i n c r e a s e d atmospheric carbon d i o x i d e (Rosenberg, 1981). Of course, carbon d i o x i d e i s not the o n l y l i m i t i n g f a c t o r i n p r o d u c t i v i t y . Water supply, n u t r i e n t a v a i l a b i l i t y and the l e n g t h of the growing season must a l s o be adequate. Fi g u r e 28 i l l u s t r a t e s the impact of v e r y h i g h i n c r e a s e s i n atmospheric FIGURE 27' P e r c e n t a 9 e i n c r e a s e s o v e r p l a n t s grown a t 330 ppm o f c a r b o n d i o x i d e i n r a t e o f p h o t o s y n t h e s i s , l e a f a r e a , and d r y w e i g h t a c c u m u l a t i o n i n f o u r p l a n t t y p e s g i v e n 12 weeks o f e x p o s u r e t o e l e v a t e d (660! ppm) c o n c e n t r a t i o n s o f c a r b o n d i o x i d e . SOURCE: C l a r k , 1 9 8 2 , p . 3 0 5 . D a t a t a k e n f r o m K r a m e r , 1 9 8 1 . 81 z i o <B s O in S 4 X o 80 70 60 50 40 30 20 10 • TOMATOES IN FIELD x SUGAR BEETS IN SAND CULTURE - SULFUR DEFICIENT 0 SUGAR BEETS IN SAND CULTURE- NORMAL A ALFALFA IN FIELD • SUGAR BEETS IN FIELD 0 0 o 1 o I o A n 1000 C 0 2 C 0 N C E 2000 N T R A T I ON 3000 P. P. M. 4000 FIGURE 28: R a t e o f p h o t o s y n t h e s i s of a l f a l f a , s u g a r b e e t s , and tomatoes exposed t o high c o n c e n t r a t i o n s of carbon d i o x i d e f o r 80 minutes i n f u l l sun. Note t h a t the s u l p h u r d e f i c i e n t sugarbeets d i d not respond t o i n c r e a s e d c o n c e n t r a t i o n s of carbon d i o x i d e . Source: Kramer, 1981, p.29. 82 carbon d i o x i d e on fo u r C3 p l a n t s . Where a necessary n u t r i e n t , sulphur was d e f i c i e n t , the i n c r e a s e d carbon d i o x i d e l e v e l made no d i f f e r e n c e to p r o d u c t i v i t y . Where n u t r i e n t s were adequate the f i x a t i o n o f carbon d i o x i d e i n c r e a s e d d r a m a t i c a l l y . O b v i o u s l y , an i n c r e a s e i n p r o d u c t i o n due to carbon d i o x i d e would have r e p e r c u s s i o n s f o r f e r t i l i z e r use. The i n c r e a s e s p r o j e c t e d f o r atmospheric carbon d i o x i d e w i l l p r obably never approach the l e v e l s i n Fig u r e 28, however Kramer (1981) does conclude t h a t p r o j e c t e d i n c r e a s e s i n atmospheric carbon d i o x i d e w i l l a f f e c t p r o d u c t i o n . ( i i ) Increased water use e f f i c i e n c y - A carbon d i o x i d e -e n r i c h e d atmosphere i s a l s o b e l i e v e d to improve the water use e f f i c i e n c y o f some p l a n t s (Rosenberg, 1981). T h i s i s because a carbon d i o x i d e - e n r i c h e d atmosphere can cause p a r t i a l c l o s i n g o f the stomates which i n c r e a s e s the r e s i s t a n c e of passage o f carbon d i o x i d e ( i n ph o t o s y n t h e s i s ) and water vapour ( i n t r a n s p i r a t i o n ) . However, Cooper (1982) p o i n t s out t h a t the passage of carbon d i o x i d e would not be hindered because o f the i n c r e a s e d carbon d i o x i d e p r e s s u r e g r a d i e n t between the atmosphere and the c e l l s o f the l e a v e s . Because the humidity g r a d i e n t would not change, t r a n s p i r a t i o n or the l o s s of water would be impeded. The improved e f f i c i e n c y of water use co u l d mean c e r t a i n p l a n t s could t h r i v e i n water-poor areas i f oth e r c o n d i t i o n s were adequate. ( i i i ) P o s s i b l e decrease i n p r o t e i n content - Cooper (1982) a l s o notes t h a t an atmosphere r i c h i n carbon d i o x i d e may lea d to a h i g h e r r a t i o of carbon t o n i t r o g e n i n p l a n t t i s s u e i f 83 there i s no a d d i t i o n a l n i t r o g e n added. Although Cooper suggests t h i s c o u l d l e a d to a decrease i n the p r o p o r t i o n o f p r o t e i n , no f u r t h e r r e s e a r c h has been done to v e r i f y t h i s . ( i v ) Longer growing season - K e l l o g g and Schware (1981) p o i n t out t h a t a 1°C r i s e i n average summertime temperature, a t m i d - l a t i t u d e s could i n c r e a s e the average growing season by approximately ten days. . (v) Increase i n weed growth, d i s e a s e and pests? -Research i n t o the impacts of a carbon d i o x i d e - e n r i c h e d atmosphere on weed growth, p l a n t d i s e a s e and p e s t s , has o n l y begun. To date study suggests: - Wild g r a s s l a n d v a r i e t i e s may s h i f t to l e s s n u t r i t i o u s v a r i e t i e s (Cooper, 1982). - C e r t a i n weeds, w e l l adapted to i n c r e a s e d carbon d i o x i d e , may f l o u r i s h (Cooper, 1982). C e r t a i n p l a n t d i s e a s e s may i n c r e a s e i n s e v e r i t y . K e l l o g g and Schware (1981) note r e s e a r c h done by Coakley (unpublished) i n which he observed an i n c r e a s e i n the s e v e r i t y of s t r i p e r u s t on w i n t e r wheat i n the the P a c i f i c Northwest. Coakley a t t r i b u t e s the i n c r e a s e t o h i g h e r than "average" winter temperatures s i n c e 1961. A warmer, wetter c l i m a t e and a l o n g e r growing season may p r o v i d e c o n d i t i o n s t h a t would a l l o w many p l a n t p e s t s to pass through a d d i t i o n a l g e n e r a t i o n s . Given t h a t some i n s e c t s can produce 84 500 to 2000 o f f s p r i n g i n 2 to 4 weeks, the e f f e c t s c o u l d be dramatic ( K e l l o g g and Schware, 1981). In summary, a carbon d i o x i d e - i n d u c e d warming co u l d have the f o l l o w i n g i m p l i c a t i o n s f o r a g r i c u l t u r e : ( i ) i n c r e a s e d p r o d u c t i v i t y , i n c r e a s e d need f o r f e r t i l i z e r s ( i i ) i n c r e a s e d water use e f f i c i e n c y ( i i i ) decrease i n percentage p r o t e i n content ( i v ) a l o n g e r growing season (v) g r a s s l a n d s with l e s s n u t r i t i o u s v a r i e t i e s ( v i ) i n c r e a s e i n c e r t a i n weeds ( v i i ) i n c r e a s e i n c e r t a i n p l a n t d i s e a s e s ( v i i i ) i n c r e a s e i n c e r t a i n p e s t s . 4.1.2 The s c e n a r i o : a g r i c u l t u r a l i m p l i c a t i o n s (a) The p r e s e n t s t a t e of a g r i c u l t u r e i n the Vancouver area When examining the impacts o f a carbon d i o x i d e - i n d u c e d warming on the a g r i c u l t u r e of the Vancouver area, i t i s important to note t h a t the r e g i o n does not, by any means, pr o v i d e adequate food to meet the needs of r e s i d e n t s . In 1983, f o r example, 70 per cent of the Vancouver area's v e g e t a b l e needs were met from o u t s i d e B r i t i s h Columbia (B.C. M i n i s t r y of A g r i c u l t u r e and Food, 1983). The r e g i o n depends on crops from elsewhere i n B r i t i s h Columbia, elsewhere i n Canada and o t h e r c o u n t r i e s ( e s p e c i a l l y the United S t a t e s ) . Impacts on the supply 85 of a g r i c u l t u r a l products i n the Vancouver r e g i o n w i l l depend on the impacts i n these o t h e r a r e a s . However, f o r the purposes of t h i s t h e s i s , o n l y the impacts i n the Vancouver r e g i o n are examined because analyses of impacts i n o t h e r areas have e i t h e r not been done o r are p r e s e n t l y being e v a l u a t e d . P r e l i m i n a r y study suggests t h a t c o a s t a l C a l i f o r n i a from which B.C. imports many f r u i t s and v e g e t a b l e s would be warmer and wetter but the C a l i f o r n i a n i n t e r i o r would be warmer and d r y e r (see F i g u r e 10 and Figure 16). The c o a s t a l area of C a l i f o r n i a o f t e n r e f e r r e d to as the " s a l a d bowl" may become too warm f o r the " c o o l " crops p r e s e n t l y grown and a s h i f t i n crop p r o d u c t i o n may be r e q u i r e d . The i n t e r i o r areas of C a l i f o r n i a would probably s u f f e r i f p r e c i p i t a t i o n decreased and temperatures i n c r e a s e d because e v a p o r a t i v e l o s s e s are a l r e a d y high and i r r i g a t i o n water i s l i m i t e d (Dracup, 1977). At p r e s e n t , i n the Lower F r a s e r V a l l e y , d a i r y i n g , v egetable and s p e c i a l h o r t i c u l t u r a l crops (such as b e r r i e s , h o l l y , and Christmas t r e e s ) are the major a g r i c u l t u r a l a c t i v i t i e s . The d a i r y i n d u s t r y i s w e l l e s t a b l i s h e d i n the area but f u r t h e r expansion i s l i m i t e d by the high c o s t s of e n t r y , p a r t i c u l a r l y i n terms of land and quota f o r m i l k p r o d u c t i o n . The Lower F r a s e r V a l l e y i s among the best areas i n Canada f o r v e g e t a b l e p r o d u c t i o n . In g e n e r a l , a g r i c u l t u r e i n the Vancouver area, i s l i m i t e d by (1) f l o o d i n g , (2) summer dryness, (3) land s p e c u l a t i o n and urban p r e s s u r e s and (4) c o m p e t i t i o n from o t h e r 86 a g r i c u l t u r a l areas, p a r t i c u l a r l y C a l i f o r n i a (Dalichow, 1972; B.C. M i n i s t r y A g r i c u l t u r e and Food and DREE, 1980). (b) The f u t u r e s t a t e o f a g r i c u l t u r e : The s c e n a r i o d e s c r i b e d i n F i g u r e 24 has s i g n i f i c a n t i m p l i c a t i o n s f o r a g r i c u l t u r e i n the Vancouver r e g i o n . An i n c r e a s e i n the mean annual temperature o f approximately 3°C could r e s u l t i n a lon g e r growing season by as much as 30 days ( K e l l o g g and Schware, 1981). Not onl y would the growing season be l o n g e r but the average temperatures would be warmer. In a d d i t i o n , an i n c r e a s e i n p r e c i p i t a t i o n , i n c r e a s e d s o i l moisture and growth enhancement i n a carbon d i o x i d e - r i c h environment, c o u l d change a g r i c u l t u r a l p r o d u c t i o n i n the Vancouver area s i g n i f i c a n t l y . As d i s c u s s e d i n S e c t i o n 4.2.2 sea l e v e l r i s e c o uld inundate many a g r i c u l t u r a l areas i n the GVRD. The major i m p l i c a t i o n s f o r a g r i c u l t u r e a r e : 1. Increased range o f crop types The range of crops t h a t t h r i v e i n the area would probably i n c r e a s e . "Cool" season crops such as peas, l e t t u c e , c a u l i f l o w e r , beans, b r u s s e l s p r o u t s and cabbage would probably not do as w e l l as they do now, but many oth e r " h e a t - l o v i n g " crops such as corn, cucumbers, asparagus, peppers and tomatoes would t h r i v e . 2. Increased p r o d u c t i v i t y and m a r k e t a b i l i t y At p r e s e n t many farmers have the same crops maturing 87 at s i m i l a r times which r e s u l t s i n an excess supply or "glut" of ce r t a i n vegetables on the market and declining returns to the farmer (Personal Communication, B.C. Ministry of Agriculture and Food). A longer, warmer growing season could allow e a r l i e r planting in Spring and l a t e r harvesting in Autumn i f other conditions were adequate. Staggered plantings could r e s u l t i n increased marketability of crops by avoiding " g l u t t i n g " the market with a p a r t i c u l a r crop. At present, some f i e l d s have limited productivity due to excessive s o i l moisture i n Spring. Planting i n Spring, even when r i s k of f r o s t has passed, i s limited u n t i l f i e l d s dry s u f f i c i e n t l y . On these f i e l d s , a longer growing season, p a r t i c u l a r l y i f accompanied by increased p r e c i p i t a t i o n and s o i l moisture, would s t i l l not permit early planting unless drainage works were undertaken. Many other f i e l d s are dry enough 'in early Spring but farmers r i s k f r o s t i f they plant early. A longer warmer growing season could allow these f i e l d s to be s i g n i f i c a n t l y more productive over a longer time period than at present. 3. Increased productivity and demands on the s o i l Increased productivity, due to a longer, warmer growing season and the growth response to increased atmospheric carbon dioxide, would place increased demands on the s o i l s . F e r t i l i z e r requirements would probably increase. 88 4. Decreased i r r i g a t i o n demand Increased water use e f f i c i e n c y by p l a n t s and i n c r e a s e d p r e c i p i t a t i o n d u r i n g the summer, co u l d overcome the problem of summer drought and decrease the need f o r i r r i g a t i o n equipment' o f t e n needed d u r i n g J u l y and August. 5. Increase i n p e s t s , weeds and d i s e a s e P e s t s , weeds and crop d i s e a s e problems c o u l d i n c r e a s e . The p o s s i b l e e x t e n t and magnitude of these problems i s not known. 6. Loss of a g r i c u l t u r a l land Because much of the f e r t i l e land used f o r a g r i c u l t u r e i n the Vancouver area i s found i n l o w - l y i n g or c o a s t a l a r e a s , many farms c o u l d be inundated, eroded or a f f e c t e d by s a l i n i t y due to sea l e v e l r i s e (see S e c t i o n 4.2.1). For example, Westham I s l a n d , where farming i s the major land use, averages o n l y 1.5 metres above sea l e v e l . Dykes surrounding Westham Island have not been b u i l t as high as dykes near urban areas due to c o s t c o n s i d e r a t i o n s . In summary, the s c e n a r i o suggests the change i n c l i m a t e c o u l d be b e n e f i c i a l f o r a g r i c u l t u r e i n the Vancouver a r e a s . However the problems of (a) markets and (b) management would have to be overcome: (a) Markets - At p r e s e n t , the l i m i t s f o r a g r i c u l t u r e are not so much c l i m a t o l o g i c a l as market l i m i t a t i o n s (B.C. M i n i s t r y o f A g r i c u l t u r e and Food and DREE, 1980 and Personal Communication, B.C. M i n i s t r y of A g r i c u l t u r e and Food). Under 89 e x i s t i n g c l i m a t i c c o n d i t i o n s , p r o d u c t i v i t y c o u l d be i n c r e a s e d through more i n t e n s i v e farming i n c l u d i n g s o i l d r a i nage, mini-greenhouses and i r r i g a t i o n works. Increased p r o d u c t i v i t y i n c o n j u n c t i o n with a d d i t i o n a l storage f a c i l i t i e s o r staggered p l a n t i n g s could guarantee more continuous marketing of v e g e t a b l e s , but the l o c a l n e s s and s m a l l s i z e o f the Vancouver area market, and American c o m p e t i t i o n mean many of these a c t i o n s are not economically a t t r a c t i v e . I f a g l o b a l warming were to d e t r i m e n t a l l y a f f e c t the areas from which Vancouver imports crops (as p r e l i m i n a r y s t u d i e s i n d i c a t e may be the case) more i n t e n s i v e farming, c o n s t r u c t i o n of storage f a c i l i t i e s , and staggered p l a n t i n g s would probably be more f e a s i b l e . (b) Land s p e c u l a t i o n and urban p r e s s u r e s on farm  land - The c o m p e t i t i o n between a g r i c u l t u r a l and urban land uses has, i n the p a s t , e s c a l a t e d the c o s t of land i n the Vancouver area and l i m i t e d the growth of a g r i c u l t u r e . Past settlement p a t t e r n s have r e s u l t e d i n small p a r c e l s i z e s (almost 80% o f farms i n the GVRD are l e s s than 130 a c r e s - 1981 Census), t h a t d i s c o u r a g e i n t e n s i v e farming and i n v i t e non-farm uses. The s m a l l p a r c e l s i z e and high c o s t of land demand t h a t r e t u r n s to land use be h i g h : i . e . , y i e l d s need to be high to meet the o p p o r t u n i t y c o s t s of land use. Greater p r o d u c t i v i t y as a r e s u l t of a g l o b a l warming may h e l p i n c r e a s e the r e t u r n s to a g r i c u l t u r a l land use. However, urban p r e s s u r e s may i n c r e a s e as the h a b i t a b l e land base s h r i n k s due to o t h e r p r e s s u r e s such as sea l e v e l r i s e . 90 4.2 I m p l i c a t i o n s f o r F l o o d i n g S e c t i o n 4.2.1 w i l l examine ( i ) the c o a s t a l i n u n d a t i o n and ( i i ) the e f f e c t s of i n c r e a s e d p r e c i p i t a t i o n on r u n o f f and f l o o d i n g . S e c t i o n 4.2.2 w i l l look a t the s c e n a r i o developed i n Chapter 3 and the s p e c i f i c i m p l i c a t i o n s f o r f l o o d i n g i n the Vancouver r e g i o n . 4.2.1 ( i ) C o a s t a l i n u n d a t i o n - Regardless o f the s c e n a r i o s developed f o r the Vancouver r e g i o n , the g l o b a l s c e n a r i o i n d i c a t e s c o a s t a l i n u n d a t i o n c o u l d occur with a carbon d i o x i d e -induced warming. Most s c i e n t i s t s agree some m e l t i n g of the p o l a r i c e caps would occur; ( C l a r k , 1982; IIASA, 1981; K e l l o g g and Schware, 1981; and Hoffman e t a l . , 1983) the time frame over which m e l t i n g c o u l d occur and the extent of m e l t i n g are much more c o n t r o v e r s i a l (Mercer, 1978). Most s c i e n t i s t s agree t h a t a 5° t o 10°C p o l a r warming would r e s u l t i n m e l t i n g of the A r c t i c i c e , however, because t h i s i c e i s p r i m a r i l y f l o a t i n g sea i c e , there would be no subsequent r i s e i n sea l e v e l . The p o s s i b l e m e l t i n g of the A n t a r c t i c i c e sheets i s more c o n t r o v e r s i a l because the behavior o f t h i s i c e i s l e s s w e l l understood. Most of the A n t a r c t i c i c e s i t s on bedrock above or under sea l e v e l and i s more than 250 m t h i c k . Two l a r g e e x t e n s i o n s or i c e s h e l v e s i n the West A n t a r c t i c are not land based: sea water flows under them. With a g l o b a l warming, the oceans c o u l d be warmer than p r e s e n t (Hoffman e t a l . , 1983) and could penetrate under more of the i c e s h e l v e s , e v e n t u a l l y 91 causing them to break o f f ( F i g u r e 29). As p i e c e s of the i c e s h e l v e s break o f f , the weight o f the remaining i c e s h e l v e s would be reduced. The s h e l v e s would s p r i n g h i g h e r out of the water l e t t i n g s t i l l more water underneath causing s t i l l more breaking to o c c u r . As these p i e c e s e n t e r the water, sea l e v e l would r i s e q u i t e suddenly. There i s concern t h a t the land based i c e would become l e s s s t a b l e without the s u p p o r t i n g s h e l v e s and may a l s o surge i n t o the watter ( G r i b b i n , 1982). In a d d i t i o n to o c e a n i c warming, the i c e sheets would be s u b j e c t to atmospheric warming. Average midsummer a i r temperatures near the i c e s h e l v e s are now about -4°C to -5°C. Thus, warming i n the p o l e s of 5°C to 10°C c o u l d i n i t i a t e m e l t i n g . Mercer (1978) s t r e s s e s t h a t once warming of t h i s e x t e n t o c c u r s , d e g l a c i a t i o n c o u l d be r a p i d - perhaps c a t a s t r o p h i c a l l y r a p i d . Estimates of the water content of the West A n t a r c t i c i c e s h e l v e s i n d i c a t e m e l t i n g c o u l d r a i s e sea l e v e l by 5 to 6 metres. Although such a r i s e c o u l d occur q u i t e r a p i d l y when i t does occur, i t i s l i k e l y such a r i s e would not begin before one hundred to f i v e hundred years from p r e s e n t (Hengeveld, 1983). The East A n t a r c t i c , i n c o n t r a s t , has been g l a c i a t e d f o r an estimated 12 to 14 m i l l i o n years (IIASA, 1981), and d e g l a c i a t i o n of t h i s i c e sheet i s estimated to take m i l l e n n i a under the envisaged s c e n a r i o f o r c l i m a t e change (Mercer, 1978). The U.S. Environmental P r o t e c t i o n Agency's r e p o r t i s probably the most e x t e n s i v e study of p o s s i b l e sea l e v e l r i s e 92 FIGURE 29: Changes i n A n t a r c t i c i c e cover w i t h a 5° t o 10° C. warmi ng. Source: Mercer, 1978, p.324. (Hoffman, e t a l . , 1983). In t h i s r e p o r t the authors develop a range of s c e n a r i o s based on assumptions concerning carbon d i o x i d e - i n d u c e d c l i m a t e change, and o c e a n i c and g l a c i a l response. They p r e d i c t t h a t thermal expansion of the ocean combined with the t r a n s f e r of i c e and snow from land to oceans would r a i s e sea l e v e l much f a s t e r than the r i s e t h a t has been t a k i n g p l a c e d u r i n g the l a s t c e n t u r y . By the year 2050, the authors estimate a r i s e of 52.6 cm to 78.9 cm, but add t h a t a r i s e as low as 23.8 cm or as h i g h as 116.7 cm can not be r u l e d out. F i g u r e 30 p r e s e n t s the f i n d i n g s i n more d e t a i l . Hoffman et a l . , (1983) b e l i e v e the a c t u a l sea l e v e l r i s e w i l l f a l l somewhere between the two mid-range s c e n a r i o s . In a d d i t i o n to the magnitude of change, the r a t e o f change i s important. Hoffman e t a l . (1983) are the f i r s t to i n d i c a t e how q u i c k l y a r i s e may o ccur (1.17 m r i s e over 50 to 60 years i n the worst-case s c e n a r i o ) . I m p l i c a t i o n s of sea l e v e l r i s e v a r y i f the r i s e o c c u r s s l o w l y and g r a d u a l l y over the next 50 to 60 years or o c c u r s i n a s e r i e s of s t e p s . R e v e l l e (1982) p o i n t s out: s o c i a l and economic a d a p t a t i o n might not be d i f f i c u l t , at l e a s t f o r the c i t i e s , i f the change were s u f f i c i e n t l y slow. Except f o r h i s t o r i c a l monuments, c i t i e s are c o n s t a n t l y being r e b u i l t even without the impetus of changing c o a s t l i n e s . The " h a l f - l i f e " o f c i t y b u i l d i n g s - the p e r i o d a f t e r which h a l f o f the b u i l d i n g s e r e c t e d i n a g i v e n year have been destroyed or r e p l a c e d - seems to be between 50 and 100 y e a r s . Thus the d i s r u p t i v e n e s s of c l i m a t i c change w i l l depend s t r o n g l y on the r a t e of change. Year 2000 2025 2050 2075 2100 Scenario High 17 , .1 54. .9 116, .7 211. .5 345. .0 Mid-range high 13. .2 39 , .3 78 . 9 136 , .8 216 . 6 Mid-range low 8. .8 26 , . 2 52. . 6 91 , . 2 144 . 4 Low 4. ,8 13. .0 23. ,8 38 , .0 56. . 2 FIGURE 3 0 : Summary of s c e n a r i o s of f u t u r e sea l e v e l r i s e i n c e n t i m e t e r s . Source: Hoffman et a l . , 1933, p.38. 95 I n d i c a t i o n s are t h a t thermal expansion of the ocean w i l l occur g r a d u a l l y but i c e and snow meltwater w i l l c o n t r i b u t e to sea l e v e l r i s e i n marginal s t e p s . However, r e s e a r c h i n t h i s area has o n l y begun (Hoffman e t a l . , 1983). Based on the l i m i t e d i n f o r m a t i o n concerning magnitude and r a t e of change the f o l l o w i n g range of s c e n a r i o s i s p o s s i b l e : (1) a 1 metre r i s e by 2050 o c c u r r i n g g r a d u a l l y d u r i n g the next 60 y e a r s . (2) a 1 metre r i s e by 2050 o c c u r r i n g i n a s e r i e s o f s t e p s d u r i n g the next 60 years as g l a c i a l i c e s h e l v e s e n t e r the ocean. (3) a 5 metre r i s e by 2080 to 2480 o c c u r r i n g g r a d u a l l y over the next 100 to 500 y e a r s . (4) a 5 metre r i s e by 2080 to 2480 o c c u r r i n g i n a s e r i e s of steps d u r i n g the next 100 to 500 y e a r s . During the l a s t c e n t u r y , r e s e a r c h e r s have estimated t h a t worldwide sea l e v e l s have r i s e n between 10 and 15 c e n t i m e t r e s (Hoffman, e t a l . , 1983). A r i s e of 1 to 5 metres over 50 t o 500 years i s t h e r e f o r e approximately 10 to 20 times g r e a t e r than h i s t o r i c a l t r e n d s . R i s e s i n sea l e v e l have s i g n i f i c a n t i m p l i c a t i o n s f o r s o c i e t y : K e l l o g g and Schware (1981) estimate 30% of the world's p o p u l a t i o n l i v e s w i t h i n 50 km o f the ocean. In the United States 11 m i l l i o n people would be d i r e c t l y a f f e c t e d by a 5 m r i s e . In F l o r i d a alone, K e l l o g g and Schware estimate t h a t 40% 9 6 of the p o p u l a t i o n (1970) would have to move. No s i m i l a r e s t i m a t e has been made f o r Canada. Sea l e v e l r i s e a l s o would l e a d to s a l t water i n t r u s i o n i n t o f r e s h water r i v e r s . T h i s c o u l d a f f e c t water supply sources f o r some c o a s t a l communities. In a d d i t i o n , i n c r e a s e d s a l i n i t y would a l t e r the ecosystems of these r i v e r s , perhaps a f f e c t i n g f i s h spawning areas. Warmer oceans may r e s u l t i n changes i n h a b i t a t c o n d i t i o n s . I f warming were t o occur too r a p i d l y , many s p e c i e s may not be abl e to adapt ( K e l l o g g and Schware, 1981). Higher sea l e v e l s mean hi g h e r water t a b l e s i n many areas e s p e c i a l l y i n g e n t l y r i s i n g c o a s t a l areas and i s l a n d s . T h i s c o u l d decrease the land's drainage c a p a c i t y and i n c r e a s e r u n o f f p a r t i c u l a r l y d u r i n g storms. ( i i ) Runoff and f l o o d i n g - Increased p r e c i p i t a t i o n may lead to i n c r e a s e d r u n o f f causing i n c r e a s e d e r o s i o n and f l o o d i n g . However r u n o f f w i l l not n e c e s s a r i l y i n c r e a s e i n r e l a t i o n t o the in c r e a s e d p r e c i p i t a t i o n because r u n o f f a l s o depends on: the type of p r e c i p i t a t i o n ( r a i n o r snow), the i n t e n s i t y , d u r a t i o n and frequency o f p r e c i p i t a t i o n and the i n f i l t r a t i o n r a t e of the ground s u r f a c e . 4.2.2 The S c e n a r i o : I m p l i c a t i o n s f o r C o a s t a l Inundation, Runoff and F l o o d i n g  ( i ) C o a s t a l Inundation - The magnitude and r a t e o f 97 p o s s i b l e l e v e l r i s e c o u l d have s e r i o u s i m p l i c a t i o n s f o r the Vancouver area where so much of the p o p u l a t i o n l i v e s so c l o s e to pr e s e n t sea l e v e l . The e x i s t i n g dyke c o n t r o l system i n the Lower F r a s e r V a l l e y would not be e f f e c t i v e i n c o n t r o l l i n g the p r o j e c t e d 1 or 5 metre r i s e i n sea l e v e l . The dykes are p r i m a r i l y intended to c o n t a i n high water l e v e l s i n the F r a s e r R i v e r . With reduced p r e c i p i t a t i o n and r u n o f f i n the F r a s e r b a s i n , the dykes would be more than adequate to c o n t a i n peak r i v e r f lows. At p r e s e n t there are approximately 80 km of sea dykes i n Richmond and D e l t a b u i l t with approximately 0.5 m o f freeboard above the 1 i n 200 year high t i d e . (In farm areas the p r o t e c t i o n i s a g a i n s t the 1:50 year high t i d e . ) I f sea l e v e l were to r i s e 1 metre, these dykes would be i n e f f e c t i v e : the 1 i n 200 year high t i d e would overtop the dykes by a t l e a s t one h a l f " m e t r e , more frequent 1 i n 25 o r 1 i n 50 year high t i d e s would r e s u l t i n more frequent overtopping or d i r e c t wave a c t i o n on the dykes t h a t could l e a d to t h e i r d e t e r i o r a t i o n . In the f o l l o w i n g a n a l y s i s of impacts, the i m p l i c a t i o n s of a g r a d u a l 5 metre r i s e i n sea l e v e l are examined i n some d e t a i l f o r the Richmond and D e l t a areas. F i v e metres i s chosen f o r examination as opposed to 1 metre because of the a v a i l a b i l i t y o f 15 f o o t (4.5 m) contour i n t e r v a l mapping. The more l i k e l y and more immediate p r o s p e c t s of a 1 metre r i s e are d i f f i c u l t t o examine g i v e n e x i s t i n g mapping. A g r a d u a l r i s e i s examined although the i m p l i c a t i o n s o f a r i s e o c c u r r i n g i n a 98 series of steps would be s i m i l a r i_f these steps could be anticipated. If they could not the impacts could be quite devastating. Figure 31 i l l u s t r a t e s the areas in Richmond, Delta and South Vancouver that would be inundated i f sea l e v e l rose by 5 metres. Shaded areas on the map indicate steeply sloping shorelines that w i l l not be inundated but could be affected by erosion by wave action. A l l of Richmond would be inundated by a 5 metre r i s e i n sea l e v e l . This would a f f e c t approximately 96 ,000 people and inundate approximately 124 sq. km of land, including 3700 hectares of a g r i c u l t u r a l land (GVRD Land Use, 1 9 8 3 ) , approxi-mately 32,000 private dwellings valued at approximately 5 b i l l i o n d o l l a r s 1 , the Vancouver International Airport, the Iona sewage treatment plant, major peat areas, and many major highways, i n d u s t r i a l and commercial areas. Most of Delta would be inundated by a 5 metre r i s e i n sea l e v e l except two major urban areas - North Delta and Tsawwassen shown on Figure 31 . Approximately 140 sq. km of land would be inundated including approximately 8 ,000 hectares of a g r i c u l t u r a l land, peat areas, major highways and the Burns Bog l a n d f i l l . Approximately 20,000 people l i v e i n areas that would 1 . Estimates are from 1981 Census; Values are those reported for private, non-farm dwellings only and are based on amounts owners expect to receive i f the dwelling were sold. 99 FIGURE 31: A r e a s i n Richmond, D e l t a and S o u t h V a n c o u v e r A f f e c t e d by a 5 M e t r e R i s e i n Sea L e v e l . AREAS INUNDATED AREAS AFFECTED BY EROSION AREAS NOT AFFECTED 100 be inundated, i n v o l v i n g approximately 6,600 p r i v a t e d w e l l i n g s v a l u e d a t approximately 1 b i l l i o n d o l l a r s . To p r o v i d e p r o t e c t i o n a g a i n s t a 5 metre r i s e i n sea l e v e l , the e x i s t i n g dykes would have to be r a i s e d 5 metres and probably more to account f o r wave and storm a c t i o n . T h i s would more than double the h e i g h t of most e x i s t i n g dykes. The f e a s i b i l i t y of r a i s i n g the dykes r e q u i r e s more d e t a i l e d a n a l y s i s but p r e l i m i n a r y examination i n d i c a t e s such a d d i t i o n s are f e a s i b l e ( P e r s o n a l Communication, M i n i s t r y o f Environment and Klohn Leonoff G e o t e c h n i c a l E n g i n e e r s ) . Techniques have been developed i n o t h e r l o w - l y i n g c o u n t r i e s such as the Netherlands to h o l d back the sea. However, the c o s t s of h o l d i n g back the sea may be very high because d o u b l i n g the h e i g h t of dykes would r e q u i r e t h a t the base of dykes be more than doubled. At p r e s e n t , the dykes r e q u i r e a 28 metre wide base; a 10 metre hi g h dyke would r e q u i r e an estimated 53 metre base. Thus there would be land a c q u i s i t i o n c o s t s i n a d d i t i o n to the d e s i g n , c o n s t r u c t i o n and m a t e r i a l s c o s t s . In some areas, the e x i s t i n g dyke m a t e r i a l may not be adequate to support a d d i t i o n a l m a t e r i a l due to ground c o n d i t i o n s or the f o r c e of the water to be r e t a i n e d . In o t h e r areas, the 5 metre a d d i t i o n may be added d i r e c t l y to the e x i s t i n g dykes ( P e r s o n a l Communication, M i n i s t r y of Environment; and Klohn Leonoff G e o t e c h n i c a l E n g i n e e r s ) . The dyking program i n the Lower F r a s e r V a l l e y , now nearing completion, upgraded and r a i s e d the dykes approximately 101 1.2 metres i n most areas at a c o s t o f $14 m i l l i o n i n D e l t a and over $21 m i l l i o n (1983 d o l l a r s ) i n Richmond. I n c r e a s i n g the h e i g h t of the dykes by an a d d i t i o n a l 5 metres would c o s t at l e a s t f i v e times these amounts - a very rough estimate of $175 m i l l i o n f o r Richmond and D e l t a e x c l u d i n g land a c q u i s i t i o n c o s t s . At p r e s e n t , dykes are c o n s t r u c t e d i f the b e n e f i t / c o s t r a t i o i s equal to 1 or more (P e r s o n a l Communication, M i n i s t r y o f E n v i r o n -ment) . These b e n e f i t / c o s t r a t i o s are determined by t o t a l l i n g the c o s t s t h a t would be a t t r i b u t a b l e to the f l o o d i f i t were to occur and comparing t h i s v a l u e to the c o s t s of f l o o d c o n t r o l . Costs of f l o o d i n g i n c l u d e primary l o s s e s , i . e . , l o s s r e s u l t i n g from damage caused by i n u n d a t i o n of l a n d , b u i l d i n g s , and o t h e r s t r u c t u r e s i n c l u d i n g damage to roads, r a i l w a y s and u t i l i t i e s . Primary l o s s e s a l s o i n c l u d e l o s s of income by people l i v i n g and/or working i n the f l o o d e d a r e a . Secondary l o s s e s i n c l u d e the l o s s of income t h a t would be s u s t a i n e d i n the surrounding area because of the i n t e r r u p t i o n of t r a n s p o r t a t i o n and communi-c a t i o n l i n k s . F i n a l l y , i n t a n g i b l e l o s s e s are t o t a l l e d , i n c l u d -ing l o s s of l i f e , s i c k n e s s or h a r d s h i p , p e r s o n a l inconvenience, e f f e c t s on w i l d l i f e , d e p r e c i a t i o n i n s c e n i c v a l u e s and any o t h e r l o s s e s not e a s i l y measured i n monetary terms. In order to take i n t o c o n s i d e r a t i o n the f a c t t h a t t h e " b e n e f i t s of f l o o d c o n t r o l w i l l be experienced f o r many years to come, an average annual b e n e f i t can be determined by d i v i d i n g the b e n e f i t s over t h e i r expected l i f e t i m e . These annual b e n e f i t s can then be compared to the annual c o s t s of f l o o d c o n t r o l ( F r a s e r R i v e r Board, 1963). 102 I f the value of p r i v a t e d w e l l i n g s alone ( e x c l u d i n g the v a l u e of highways, sewage treatment p l a n t , i n d u s t r y , commerce, m u l t i p l e f a m i l y d w e l l i n g s , farmland and o t h e r land u s e s ) , i n Richmond and D e l t a i s approximately 6 b i l l i o n d o l l a r s and the rough e s t i m a t i o n of a d d i t i o n a l dyke c o n s t r u c t i o n i s $175 m i l l i o n , the b e n e f i t / c o s t r a t i o would probably be much g r e a t e r than one but much more d e t a i l e d a n a l y s i s i s r e q u i r e d . T h i s v e r y rough a n a l y s i s suggests t h a t a d d i t i o n a l dyke c o n s t r u c t i o n would be c o s t e f f e c t i v e and f e a s i b l e . Perhaps f u r t h e r a n a l y s i s w i l l r e v e a l t h a t e v a c u a t i o n and r e s e t t l e m e n t may be more f e a s i b l e i n c e r t a i n areas. I f f l o o d i n g of the F r a s e r R i v e r were reduced due to decreased p r e c i p i t a t i o n i n the drainage b a s i n , as p r e l i m i n a r y s t u d i e s i n d i c a t e (see below) the e x i s t i n g r i v e r dykes would be b e t t e r a b l e than a t p r e s e n t , to c o n t a i n the r i v e r a t the lower peak flow. However the F r a s e r R i v e r i s a f f e c t e d by t i d e s as f a r upstream as M i s s i o n and the dykes may not be adequate to handle h i g h e r t i d e s due to sea l e v e l r i s e . Upstream storage may be a p a r t i a l a l t e r n a t i v e to a d d i t i o n a l dyking along the F r a s e r R i v e r , although l e s s d e s i r a b l e i f p r e c i p i t a t i o n and r u n o f f decrease. The r a t e a t which sea l e v e l r i s e o ccurs w i l l have important i m p l i c a t i o n s f o r the Vancouver area. I f a 1 to 5 metre r i s e o c c u r s g r a d u a l l y over the next 60 to 100 y e a r s , t h i s would mean a r i s e of approximately 1.6 to 5 cm per year. F i v e to twenty years of such i n c r e a s e s would probably be necessary 103 before a trend would be d e t e c t e d . Inundation, f l o o d i n g and c o a s t a l e r o s i o n would occur s l o w l y and response to change would not have to be immediate. If a 1 to 5 metre r i s e o c c u r r e d i n a s e r i e s of steps over the next 60 to 100 y e a r s , the i m p l i c a t i o n s could be more s e r i o u s . Unless the steps can be p r e d i c t e d with any c e r t a i n t y , i n u n d a t i o n , f l o o d i n g and c o a s t a l e r o s i o n c o u l d occur q u i t e suddenly. ( i i ) Runoff and f l o o d i n g - In the Vancouver a r e a , a t p r e s e n t , there are two causes of f l o o d i n g : (a) Snowmelt combined with heavy r a i n f a l l f r e q u e n t l y le a d s to f l o o d i n g and e r o s i o n i n the s p r i n g i n the mountainous areas. Increases i n s p r i n g f l o o d i n g may occur i f snowpack were to i n c r e a s e ( u n l i k e l y with an i n c r e a s e i n temperature) or i f m e l t i n g were to occur more suddenly ( a l s o u n l i k e l y ) . Average r u n o f f may be g r e a t e r i n volume a l l year round due to i n c r e a s e d p r e c i p i t a t i o n . Most s i g n i f i c a n t would be the i n c r e a s e i n the s e v e r i t y of storms i n d i c a t e d by the s c e n a r i o . Heavy r a i n f a l l s , e s p e c i a l l y i f they c o i n c i d e with snowmelt r u n o f f could cause more fre q u e n t f l o o d i n g when storm sewers reach c a p a c i t y . In the D i s t r i c t o f West Vancouver, f o r example, r a i n f a l l i n t e n s i t i e s p r e s e n t l y can and do exceed the c a p a c i t y of drainage f a c i l i t i e s (Dayton and Knight, 1973 and P e r s o n a l Communication, D i s t r i c t of West Vancouver). Combined with (1) plugging of c u l v e r t s , b r i d g e s , and watercourses^by waterborne d e b r i s , (2) n a t u r a l e r o s i o n of watercourses, and (3) the replacement o f p e r v i o u s 104 ground by impervious s u r f a c e s , drainage c o u l d become a more s e r i o u s concern i f i n t e n s i t y of storms were to i n c r e a s e . (b) The worst f l o o d s i n the Vancouver area have o c c u r r e d when the l e v e l of the F r a s e r R i v e r has r i s e n due to sudden m e l t i n g o f the snowpack i n the mountains of the c e n t r a l and e a s t e r n i n t e r i o r of the P r o v i n c e . P r e l i m i n a r y i n d i c a t i o n s f o r g l o b a l c i r c u l a t i o n models and p a l e o c l i m a t i c evidence suggest the i n t e r i o r o f B r i t i s h Columbia w i l l be d r y e r and warmer i f the GAST i n c r e a s e s by 2.5°C ( K e l l o g g , 1979; C l a r k , 198 2). With warmer, d r y e r c o n d i t i o n s , snowpack would not be as heavy as a t p r e s e n t . Spring r u n o f f would be l e s s i n volume, thus re d u c i n g the danger of f l o o d i n g from t h i s source. 4.3 Water Supply The s c e n a r i o suggests t h a t there w i l l be i n c r e a s e d p r e c i p i t a t i o n and i n c r e a s e d temperatures i n the Vancouver a r e a . These two f a c t o r s have i m p l i c a t i o n s f o r the water supply system i n the Vancouver area. Present s u p p l i e s depend on r u n o f f from r a i n f a l l and snowmelt i n l o c a l mountains. At p r e s e n t t h i s r u n o f f p r o v i d e s ample water f o r the Vancouver area approximately 98 per cent of the year. Shortages occur o n l y i n J u l y and August during extended hot r a i n - f r e e p e r i o d s . During these times demand f o r lawn and garden s p r i n k l i n g i n c r e a s e s d r a m a t i c a l l y p u t t i n g g r e a t e r demands on the water system. In a d d i t i o n , by J u l y most of the snowpack - the n a t u r a l storage f a c i l i t y - has melted, 105 thus r u n o f f i s low. R e s t r i c t i o n s on use are u s u a l l y necessary d u r i n g these times. However, a t prese n t there are no p l a n s to expand the system ( P e r s o n a l Communication, GVRD). If temperatures i n c r e a s e as i n d i c a t e d by the s c e n a r i o , snowpack i n the l o c a l mountains may be c o n s i d e r a b l y l i g h t e r with peak r u n o f f o c c u r r i n g much e a r l i e r than a t pr e s e n t . With winter temperatures i n c r e a s i n g by as much as 5°C, much more p r e c i p i t a -t i o n may occur as r a i n r a t h e r than snow. Without the snow a c t i n g as a n a t u r a l storage f a c i l i t y , the supply o f water i n summer may decrease although t h i s would be o f f s e t by a s l i g h t i n c r e a s e i n summer r a i n f a l l . I n c r e a s i n g temperatures, p a r t i c u l a r l y i n summer, may pr o v i d e more s u i t a b l e c o n d i t i o n s f o r b a c t e r i a to t h r i v e i n the water supply system. As w e l l , warmer weather may r e s u l t i n the more frequent formation of an i s o t h e r m i c b a r r i e r i n the r e s e r v o i r s when a l a y e r o f warm water o v e r l a y s c o l d bottom water. When t h i s o c c u r s c i r c u l a t i o n i s impeded and the water can become b r a c k i s h . At p r e s e n t , i s o t h e r m i c s t r a t i f i c a t i o n o c c a s i o n a l l y occurs i n the Capilano R e s e r v o i r and a i r must be pumped i n to mix the l a y e r s . The onl y o t h e r treatment t h a t Vancouver water r e c e i v e s i s a l i g h t c h l o r i n a t i o n treatment t o c o n t r o l b a c t e r i a . Both a e r a t i o n and c h l o r i n a t i o n may have to be undertaken more f r e q u e n t l y with i n c r e a s e d temperatures ( P e r s o n a l Communication, GVRD). 106 4.4 Human Settlement Human sett l e m e n t p a t t e r n s develop i n response t o c l i m a t e and the f a c t o r s a l r e a d y mentioned - a g r i c u l t u r e , water supp l y , sea l e v e l s , and r u n o f f c o n d i t i o n s - but are a l s o a r e s u l t o f many other f a c t o r s such as a c c e s s i b i l i t y to re s o u r c e s o r t r a n s p o r t a t i o n , p e r c e p t i o n o f r i s k and a t t r a c t i v e n e s s . Growth f o r e c a s t s f o r the GVRD i n d i c a t e the p o p u l a t i o n w i l l i n c r e a s e s l o w l y by 284,040 people by the year 2001 (from 1,169,820 i n 1981 to 1,456,860 i n 2001). T h i s new p o p u l a t i o n i s p r o j e c t e d to be d i s t r i b u t e d between the c e n t r a l urban areas which w i l l a t t r a c t non-family households and suburban areas which w i l l a t t r a c t f a m i l i e s (GVRD, 1983). These set t l e m e n t f a c t o r s and growth trends could be a f f e c t e d by a carbon d i o x i d e - i n d u c e d warming. The r e s u l t could range from a f o r c e d r e - d i s t r i b u t i o n of p o p u l a t i o n w i t h i n the Vancouver r e g i o n t o a mass move to othe r more advantageously a f f e c t e d areas. Conversely, c o n d i t i o n s elsewhere i n the world c o u l d r e s u l t i n an i n f l u x o f people i n t o the r e g i o n . Climate change has, i n the p a s t , l e d to m i g r a t i o n : d u r i n g the p e r i o d 1845-1851, almost h a l f o f I r e l a n d ' s p o p u l a t i o n migrated to the United S t a t e s and B r i t a i n when warm, moist summers c r e a t e d i d e a l c o n d i t i o n s f o r a pot a t o b l i g h t fungus. The s c e n a r i o o u t l i n e d i n F i g u r e 24 w i l l b r i n g about changes i n a g r i c u l t u r e , sea l e v e l s and r u n o f f and water supply as d e s c r i b e d i n S e c t i o n s 4.1 through 4.3. Changes w i l l a l s o occur i n p o l l u t i o n l e v e l s and i n c i d e n c e s o f f o g . The f o l l o w i n g 107 s e c t i o n s w i l l examine how a l l of these changes could a f f e c t human set t l e m e n t . 4.4.1 Human sett l e m e n t and a g r i c u l t u r e A s h i f t i n human s e t t l e m e n t p a t t e r n s w i t h i n the GVRD due t o changes i n a g r i c u l t u r a l p r a c t i c e s would probably not occur unless areas from which foods are imported are d e t r i m e n t a l l y a f f e c t e d by a carbon d i o x i d e - i n d u c e d warming. I f t h i s were t o oc c u r , a g r i c u l t u r a l land i n the Vancouver area would probably i n c r e a s e i n v a l u e . The presen t development p r e s s u r e s on a g r i c u l t u r a l land may be countered somewhat by the i n c r e a s i n g v a l u e of a g r i c u l t u r a l l a n d . In a d d i t i o n , with g r e a t e r p r o d u c t i v i t y the a g r i c u l t u r a l i n d u s t r y may be able to support a l a r g e r p o p u l a t i o n i n the Vancouver area. With these p r e s s u r e s on urban areas - the p o s s i b l e i n c r e a s e d value o f a g r i c u l t u r a l l a n d , and the a b i l i t y to support a s l i g h t l y l a r g e r p o p u l a t i o n - e x i s t i n g i n f e r t i l e l and may have to support higher d e n s i t i e s o f r e s i d e n t i a l , i n d u s t r i a l and commercial uses. Combined with p r e s s u r e s from r i s i n g sea l e v e l s i n low land areas and r u n o f f f l o o d i n g i n mountainous areas (see S e c t i o n 4.3.2) and continued, although slow p o p u l a t i o n growth, the h a b i t a b l e land base c o u l d s h r i n k p a r t i c u l a r l y i f major dyking were not undertaken. 108 4.4.2 Human Settlement, C o a s t a l Inundation, F l o o d i n g and Runoff The changes i n sea l e v e l , f l o o d i n g and r u n o f f d e s c r i b e d i n S e c t i o n 4.2 imply many changes f o r human sett l e m e n t i n the Vancouver a r e a . The major changes would i n v o l v e a p o s s i b l e r e d i s t r i b u t i o n of p o p u l a t i o n and an i n c r e a s e d d e n s i t y i n a l r e a d y i n h a b i t e d areas. Sea l e v e l r i s e which would have the b i g g e s t impact, would f o r c e human se t t l e m e n t to high e r e l e v a t i o n s i f major dyking were not undertaken. With i n c r e a s i n g temperatures and l e s s s n o w f a l l , a n a t u r a l l o c a t i o n f o r new sett l e m e n t would be the nor t h shore mountains. At p r e s e n t , the D i s t r i c t s o f North and West Vancouver l i m i t development to below 320 metres and 365 metres r e s p e c t i v e l y , due to the d i f f i c u l t y and high c o s t of p r o v i d i n g s e r v i c e s and m a i n t a i n i n g access d u r i n g winter months (Per s o n a l Communication, D i s t r i c t s o f North and West Vancouver). With l e s s s n o w f a l l , development may be f e a s i b l e a t hi g h e r e l e v a t i o n s . Of a l l the impacts i d e n t i f i e d , r e d i s t r i b u t i o n of settlement due to a p o s s i b l e r i s e i n sea l e v e l , would change the c h a r a c t e r o f the Vancouver area most p r o f o u n d l y . In a d d i t i o n , i t would be the most traumatic and c o s t l y impact. I f sea l e v e l r i s e were to occur i n a s e r i e s of steps t h a t c o u l d not be p r e d i c t e d , the d i s r u p t i o n to human se t t l e m e n t c o u l d be e x t e n s i v e . I f change i n sea l e v e l were to occur g r a d u a l l y , human sett l e m e n t would have time t o a d j u s t through dyke c o n s t r u c t i o n o r gr a d u a l r e s e t t l e m e n t . 109 4.4.3 Human Settlement and Water Supply Human sett l e m e n t may be a f f e c t e d by changes i n the water supply system but no major r e d i s t r i b u t i o n of people or lan d use i s probable. For some people, the Vancouver area may become a l e s s d e s i r a b l e p l a c e to l i v e due to lowered water q u a l i t y but the d e g r a d a t i o n of the water would probably not be s e r i o u s . In terms of q u a n t i t y , i t i s l i k e l y there w i l l be a need f o r a d d i t i o n a l or deeper r e s e r v o i r s ( P e r s o n a l Communication, GVRD). 4.4.4 Human Settlement and P o l l u t i o n At p r e s e n t the p o o r e s t a i r q u a l i t y i n Vancouver o c c u r s i n summer under a n t i c y c l o n i c c o n d i t i o n s when s o l a r r a d i a t i o n i s i n t e n s e and winds are l i g h t . Although o t h e r p o l l u t a n t s some-times reach h i g h l e v e l s , ozone i s the p r i n c i p a l concern (GVRD, 1982). Ozone can i r r i t a t e the eyes, nose, and t h r o a t and i n c r e a s e s u s c e p t i b i l i t y to r e s p i r a t o r y d i s e a s e s such as asthma and emphysema. In a d d i t i o n , ozone can reduce crop y i e l d s , i n s t i g a t e the breakdown of rubber products and decrease a t h l e t i c performance (GVRD, 1982). Ozone i s formed as a r e s u l t of a photochemical r e a c t i o n of strong sunshine with hydrocarbons and n i t r o g e n oxides r e l e a s e d i n the combustion, t r a n s f e r and improper storage of f u e l . Maximum ozone l e v e l s occur between the months of A p r i l t o August between noon and e a r l y evening when r a d i a t i o n i s s t r o n g e s t and winds calm. The same photochemical r e a c t i o n i s 110 r e s p o n s i b l e f o r the heavy p e r s i s t e n t smogs i n San F r a n c i s c o (Bay Area P o l l u t i o n C o n t r o l D i s t r i c t , 1974). In the Vancouver r e g i o n , s o l a r r a d i a t i o n i s not as strong and l i g h t winds u s u a l l y d i s p e r s e the ozone up the F r a s e r V a l l e y . During the 1978 to 1983 ozone l e v e l s i n the l o c o / Buntzen area exceeded L e v e l A (Maximum D e s i r a b l e L e v e l o f 0.05 ppm average c o n c e n t r a t i o n over a one hour pe r i o d ) approximately 7 per cent o f the time each year. L e v e l B (Maximum Acceptable Level o f 0.08 ppm average c o n c e n t r a t i o n over a one hour pe r i o d ) was exceeded approximately 1.5 per cent o f the time each year. The maximum recorded l e v e l f o r the average c o n c e n t r a t i o n over a one hour p e r i o d i n 1983 was 0.169 ppm i n Port Moody. Compared to ozone l e v e l s reached i n San F r a n c i s c o , the l e v e l s reached i n Vancouver appear low. During 1975, f o r example, Canada's L e v e l B o f 0.08 ppm, was exceeded a p p r o x i - . mately 20 per cent o f the time i n San F r a n c i s c o . In p a r t s o f San F r a n c i s c o l e v e l s up t o 0.21 ppm were reached; exceeding the Maximum T o l e r a b l e l e v e l o f 0.153 ppm e s t a b l i s h e d by the Canadian Government. San F r a n c i s c o has had to i n t r o d u c e c o n t r o l s on automobiles, storage of f u e l , r e s t r i c t i o n s on use of hydrocarbon-based p a i n t s , and has a "Smog Advisory" system i n p l a c e (Bay Area P o l l u t i o n C o n t r o l D i s t r i c t , 1974). With i n c r e a s e d u r b a n i z a t i o n and i n d u s t r i a l i z a t i o n , l i k e l y to accompany slow p o p u l a t i o n growth (GVRD, 1983) , combustion, storage and t r a n s f e r o f f u e l , i n the Vancouver area i s l i k e l y to i n c r e a s e g r a d u a l l y . I f i n a d d i t i o n , a n t i c y c l o n i c I l l c o n d i t i o n s are more p r e v a l e n t and temperatures are high e r as i n d i c a t e d by the s c e n a r i o , ozone w i l l probably become more p r o b l e m a t i c a l . I f onshore breezes are more v i g o r o u s , the ozone c o u l d continue to be d i s p e r s e d up the F r a s e r V a l l e y . How co u l d i n c r e a s e d ozone l e v e l s a f f e c t human s e t t l e m e n t i n Vancouver? I f the problem p e r s i s t e d , c e r t a i n areas would become l e s s d e s i r a b l e f o r r e s i d e n t i a l uses. Some of these areas would a l s o be under p r e s s u r e s from sea l e v e l r i s e s . These p r e s s u r e s would decrease the h a b i t a b l e land area i n the Vancouver area. 4.4.5 Human Settlement and Fog At p r e s e n t , the Vancouver area experiences approximately 20 to 30 days per year with fog (Hay and Oke, 1976). A day with fog i s d e f i n e d as a day (24 hours) i n which fog p e r s i s t s such t h a t v i s i b i l i t y i s decreased to l e s s than 1 km a t l e a s t once due to fog alone ( F a u l k n e r , 1978). Previous to 1960, t h i s r a t e o f fog i n c i d e n c e was much h i g h e r - approximately 70 t o 80 days per year (see Fig u r e 3 2). The decrease i s b e l i e v e d t o be p a r t i a l l y due to anthropogenic reasons: p r i m a r i l y a s h i f t from burning of sawdust and c o a l t o o i l and gas which r e s u l t e d i n l e s s a i r b o r n e n u c l e i on which water d r o p l e t s could condense. A carbon d i o x i d e induced warming co u l d r e t u r n us to the pre-1960 e r a when fog i n c i d e n c e s were much higher. Increased fog c o u l d l e a d to t r a n s p o r t a t i o n hazards e s p e c i a l l y at the Vancouver I n t e r n a t i o n a l A i r p o r t and on l o w - l y i n g highways and 112 o I 1 1 1 i 1940 1950 1960 1970 FIGURE 32: Days w i t h fog from a p p r o x i m a t e l y 1940 t o 1978. Note steady decrease s i n c e 1960. Source: F a u l k n e r , 1978, p.10. 113 marine t r a n s p o r t a t i o n c o r r i d o r s . Transportation-dependent i n d u s t r y may f i n d Vancouver a l e s s d e s i r a b l e l o c a t i o n . Residents may a l s o f i n d t r a v e l i s inconvenienced. There may be s h i f t s i n se t t l e m e n t p a t t e r n s as fog-prone areas become l e s s d e s i r a b l e i n which to l i v e . 4.5 Summary of Environmental, S o c i a l and Economic I m p l i c a t i o n s  Chapter 4 has examined the i m p l i c a t i o n s of the c l i m a t i c s c e n a r i o developed i n Chapter 3 ( F i g u r e 24). In t h i s s e c t i o n these i m p l i c a t i o n s are p r i o r i z e d a c c o r d i n g to the p o t e n t i a l r a t e of change: (a) Severe impacts would be those with (1) the widest magnitude of p o t e n t i a l e f f e c t s . P o t e n t i a l impacts would a f f e c t a wide geographic area and a f f e c t many people and s e c t o r s o f s o c i e t y ; (2) the widest e x t e n t o f p o t e n t i a l e f f e c t s , i . e . , severe impacts would be the most s o c i a l l y , e n v i r o n m e n t a l l y and ec o n o m i c a l l y d i s r u p t i v e . These impacts would be p o t e n t i a l l y t h r e a t e n i n g to l i f e or p r o p e r t y ; and (3) the most immediacy, i . e . , the r a t e of change imposed on s o c i e t y by these severe impacts could be q u i t e r a p i d . (b) Important impacts would be e n v i r o n m e n t a l l y , e c o n o m i c a l l y o r s o c i a l l y d i s r u p t i v e but would not t h r e a t e n l i f e or p r o p e r t y . Important impacts would occur s t e a d i l y but not as r a p i d l y as severe impacts. (c) Minor impacts would be l i m i t e d i n magnitude and 114 extend of p o t e n t i a l e f f e c t s . Impacts would be f e l t by o n l y c e r t a i n s e c t o r s of s o c i e t y or by c e r t a i n g e o g r a p h i c a l a r e a s . Such changes may r e q u i r e adjustment by s o c i e t y but are not o v e r l y d i s r u p t i v e . Rate of change would be slow and g r a d u a l . In the f o l l o w i n g , the impacts are c l a s s e d as s e v e r e , important or minor: (a) Severe impacts: The most severe impact i d e n t i f i e d i s c o a s t a l i n u n d a t i o n and e r o s i o n due to sea l e v e l r i s e and the accompanying impacts on dykes, human sett l e m e n t and a g r i c u l t u r e . (b) Important impacts: Important impacts i n c l u d e changes i n a g r i c u l t u r a l p r o d u c t i o n and p r a c t i c e s and changes i n r u n o f f c o n d i t i o n s . (c) Minor impacts: Other impacts c o n s i d e r e d minor i n importance i n c l u d e changes i n q u a l i t y and q u a n t i t y of water supply and changes i n p o l l u t i o n and fog l e v e l s . A l l o f these impacts are g e n e r a l l y d e t r i m e n t a l to s o c i e t y . Except f o r p o s s i b l e a g r i c u l t u r a l b e n e f i t s and the lessened r i s k o f f l o o d i n g of the F r a s e r R i v e r , a carbon d i o x i d e -induced g l o b a l warming c o u l d b r i n g s o c i a l , economic and e n v i r o n -mental d i s r u p t i o n . P a r t of the purpose of Chapter 5 i s to determine how t h i s d i s r u p t i o n can be minimized and how the b e n e f i t s can be o p t i m i z e d . CHAPTER 5 115 APPROPRIATE ACTIONS The f i r s t p a r t of Chapter 5 examines the types o f a c t i o n s and i m p l i c a t i o n s of the a c t i o n s t h a t s o c i e t y can take i n response to a p o t e n t i a l carbon d i o x i d e - i n d u c e d g l o b a l warming. Th i s s e c t i o n a l s o examines the o b s t a c l e s that hinder the implementation o f v a r i o u s s t r a t e g i e s . Secondly, Chapter 5 recommends s t r a t e g i e s t h a t c o u l d be taken i n the Vancouver area to d e a l with the s p e c i f i c impacts i d e n t i f i e d i n Chapter 4 . 5.1 What are the choices? The s t r a t e g i e s t h a t can be taken i n response to a carbon d i o x i d e - i n d u c e d warming i n c l u d e : (a) do nothing, i . e . , postpone any a c t i o n ; (b) do more r e s e a r c h , i . e . , f u r t h e r d e f i n e the problem and examine p o s s i b l e responses; (c) take a c t i o n now, i . e . , prevent the b u i l d - u p o f carbon d i o x i d e i n the atmosphere and/or make the human systems t h a t may be a f f e c t e d more r e s i l i e n t ; (d) monitor changes and r a t e s of changes; (e) develop contingency plans f o r adapting when necessary. According to C l a r k e t a l . (1982, p. x i i i ) , the "Why?" of the carbon d i o x i d e q u e s t i o n i s beginning to be understood 116 ( i n c l u d i n g the ext e n t of u n c e r t a i n t y ) but the "So What?" remains e l u s i v e . In l i g h t of these u n c e r t a i n t i e s i n v o l v e d i n the carbon d i o x i d e i s s u e , policy-makers can e a s i l y be tempted t o ignore the "So What?" q u e s t i o n and r a t i o n a l i z e postponing a c t i o n . The "Do Nothing" and "Do More Research" c h o i c e s are the e a s i e s t responses, e s p e c i a l l y when s c i e n t i s t s themselves cannot agree on the impacts and the impacts w i l l not be apparent i n the immediate f u t u r e . On the b a s i s of these reasons, i t i s not d i f f i c u l t f o r policy-makers to j u s t i f y postponing a c t i o n . However they can a l s o choose t o take a c t i o n now to prevent a b u i l d - u p of atmospheric carbon d i o x i d e o r to develop contingency p l a n s f o r adapting to changes that may occur. In a democratic s o c i e t y , the c h o i c e between postponement, p r e v e n t i o n or a d a p t a t i o n i s i d e a l l y made by w e l l -informed e l e c t e d d ecision-makers. However, when d e a l i n g with an i s s u e such as carbon d i o x i d e - i n d u c e d c l i m a t e change, problems a r i s e because s c i e n t i s t s who understand the u n c e r t a i n t i e s i n v o l v e d , are o f t e n h e s i t a n t to be r e s p o n s i b l e f o r p r o v i d i n g tenuous i n f o r m a t i o n f o r the decision-making p r o c e s s . An unnamed p a r t i c i p a n t at a conference on the carbon d i o x i d e i s s u e emphasized the need f o r s c i e n t i s t s t o admit the l i m i t a t i o n s o f t h e i r i n f o r m a t i o n : I get very upset a t the idea t h a t we should make the u n i l a t e r a l d e c i s i o n as s c i e n t i s t s to withhold some p i e c e of evidence, which may have some p o l i c y e f f e c t , because we, i n our p e r s o n a l 117 p h i l o s o p h i e s , do not t h i n k t h a t evidence i s s u f f i c i e n t to j u s t i f y a c t i o n . Let o t h e r s make th a t d e c i s i o n . Put out the evidence but make sure you s t a t e i t s u n c e r t a i n t y . ( i n Mead and K e l l o g g , 1980, p. 71) The c h o i c e s made by policy-makers need to be based not o n l y on an understanding of the i n f o r m a t i o n t h a t i s a v a i l a b l e but a l s o on the r e a l i z a t i o n t h a t t h i s i n f o r m a t i o n i s sometimes formulated on u n c e r t a i n knowledge. Policy-makers need to be aware of what O'Connor (1978) terms the "known unknowns". Rutgers (1977) notes t h a t c l i m a t o l o g i s t s , l i k e o t h e r s c i e n t i s t s have found i t d i f f i c u l t t o admit the l i m i t a t i o n s o f t h e i r f i e l d : C l i m a t o l o g i s t s have, by t h e i r own c o n f e s s i o n , not been very e f f e c t i v e i n d e v eloping a human response t o c l i m a t i c v a r i a b i l i t y ... O v e r l y concerned with e s t a b l i s h i n g s c i e n t i f i c t r u t h beyond reasonable doubt, l i t t l e i n f o r m a t i o n has been passed onto p o l i t i c i a n s and po l i c y - m a k e r s , who have consequently based d e c i s i o n s on ignorance r a t h e r than u n c e r t a i n t y , (p.62) Decision-makers may f i n d choosing courses of a c t i o n v e r y d i f f i c u l t when they are aware of the u n c e r t a i n t i e s i n v o l v e d . The temptation may be to c a l l f o r "more r e s e a r c h " i n t o the unknowns. Indeed, r e s e a r c h needs must be d e f i n e d and p r i o r i z e d , but some a c t i o n may have to be taken on the b a s i s of the knowledge p r e s e n t l y a v a i l a b l e . If we await the r e s u l t s o f f u r t h e r r e s e a r c h , change may be more d i f f i c u l t t o a v e r t or a m e l i o r a t e . Schneider and Masirow (1976) suggest the ...dilemma r e s t s , m e t a p h o r i c a l l y , 118 i n our need to gaze i n t o a very d i r t y c r y s t a l b a l l ; but the tough judgement to be made here i s p r e c i s e l y how long we should c l e a n the g l a s s b e f o r e a c t i n g on what we b e l i e v e we see i n s i d e . (p. 149) H o l l i n g (1978) emphasizes t h a t d e s p i t e r e s e a r c h , the domain of our knowledge of systems remains small when compared to t h a t of our ignorance. Attempts to reduce t h i s u n c e r t a i n t y are admirable but these attempts must be "accompanied by an equal e f f o r t to d e s i g n f o r u n c e r t a i n t y and to o b t a i n b e n e f i t s from the unexpected" (p. 9). In the face of t h i s dilemma i t i s s i g n i f i c a n t t h a t many re s e a r c h e r s who r e c o g n i z e the need f o r more r e s e a r c h , a l s o b e l i e v e the p r e v e n t i v e , c o n t i n g e n t and a d a p t i v e a c t i o n s we may take, are a c t i o n s we should be t a k i n g i n any case to d e a l with short-term c l i m a t i c v a r i a b i l i t y and o t h e r u n r e l a t e d economic, s o c i a l and environmental concerns such as a c i d r a i n , e r o s i o n o f a g r i c u l t u r a l s o i l ( C l a r k e t a l . , 1982; Cooper, 1982; T i c k e l l , 1979; Schneider and Temkin, 1978). 5.2 Are There P r e v e n t i v e S t r a t e g i e s ? A number of means of p r e v e n t i n g a b u i l d - u p of carbon d i o x i d e i n the atmosphere have been proposed i n c l u d i n g the f o l l o w i n g : (a) T e c h n o l o g i c a l " f i x e s " have been suggested such as p l a c i n g a l a y e r of dust i n the atmosphere t h a t would r e f l e c t s o l a r energy i n t o space (Schneider and Temkin, 1978) o r 119 c o l l e c t i n g carbon d i o x i d e . a t the s i t e of combustion o f f o s s i l f u e l s and p i p i n g i t to the depths o f the ocean (Schneider and Temkin, 1978; K e l l o g g and Schware, 1981; M a r c h e t t i , 1977). Both o f these methods would be v e r y expensive and would r e q u i r e i n t e r n a t i o n a l c o o p e r a t i o n . The f u l l e f f e c t s o f a l a y e r of dust i n the atmosphere or adding carbon d i o x i d e to the ocean depths are not known, and would undoubtedly be c o n t r o v e r s i a l . In a d d i t i o n c o o p e r a t i o n would be d i f f i c u l t t o a t t a i n when some c o u n t r i e s are l i k e l y to b e n e f i t from a carbon d i o x i d e - i n d u c e d warming, and thus would not be i n t e r e s t e d i n p r e v e n t i o n . (b) The fundamental s o l u t i o n i s to switch to o t h e r energy sources t h a t do not emit carbon d i o x i d e t o the atmosphere as s o l a r , wind or n u c l e a r power. At p r e s e n t , n e i t h e r s o l a r or wind power are f e a s i b l e on a l a r g e enough s c a l e to be e c o n o m i c a l l y f e a s i b l e , although both are g e n e r a l l y c o n s i d e r e d due to t h e i r n o n - p o l l u t i n g , non-consumptive nature. Nuclear power may become more common but there s t i l l e x i s t many problems concerning a c c i d e n t a l leakage and d i s p o s a l o f n u c l e a r waste. Changes to s o l a r , wind or n u c l e a r power w i l l not occur e a s i l y o r without a g r e a t d e a l of o p p o s i t i o n . At p r e s e n t , v a s t amounts o f c a p i t a l investment are t i e d up, world-wide, i n the e x p l o r a t i o n , development and combustion o f f o s s i l f u e l s . Even i f the t r a n s f o r m a t i o n to other sources could be made, the C o u n c i l on Environmental Q u a l i t y (1981) notes t h a t " h i s t o r i c a l l y , i t has taken about 100 years f o r a new energy system to move from 1 per cent to 50 per cent of t o t a l supply" (p. 62). The switch to 120 o t h e r energy sources would have to occur f a s t e r than ever before i n human h i s t o r y . (c) By reducing f o s s i l f u e l consumption through c o n s e r v a t i o n , the c o n c e n t r a t i o n of atmospheric carbon d i o x i d e c o u l d be he l d a t or near p r e s e n t l e v e l s (Meyer-Abich, 1 9 8 0 ) . Reducing consumption would, a g a i n , r e q u i r e i n t e r n a t i o n a l c o o p e r a t i o n and would take time to i n s t i g a t e . Meyer-Abich (198 0) notes t h a t , at l e a s t i n the United S t a t e s , there are a l r e a d y strong n a t i o n a l i n c e n t i v e s to conserve and y e t l i t t l e i s being done t o t h i s end. He adds: " i f the a c t u a l o i l c r i s i s does not convince the American people t h a t o i l should be s u b s t i t u t e d by c o n s e r v a t i o n ... and by a l t e r n a t i v e ... f u e l s ... p r o s p e c t s of c l i m a t i c change w i l l not convince them e i t h e r " (p. 65). (d) Schneider and Temkin (1978) suggest t h a t by l i m i t i n g p o p u l a t i o n growth, t o t a l energy needs w i l l be reduced and t h e r e f o r e carbon d i o x i d e emissions reduced. Although p o p u l a t i o n growth i n most developed c o u n t r i e s i s minimal, growth i n d e v eloping c o u n t r i e s i s p r o j e c t e d to remain high f o r a t l e a s t the next twenty years (Mauldin, 1 9 8 0 ) . The e x i s t i n g age s t r u c t u r e , m o r t a l i t y and f e r t i l i t y r a t e s c r e a t e a growth momentum t h a t would be d i f f i c u l t to c o u n t e r a c t . Any e f f o r t s t o c u r t a i l t h i s growth would take a long time t o implement and would r e q u i r e i n t e r n a t i o n a l c o o p e r a t i o n t o be e f f e c t i v e . (e) A d d i t i o n a l t a x a t i o n o f f o s s i l f u e l s , o r banning the use of c e r t a i n f u e l s has been suggested as a means of 121 encouraging c o n s e r v a t i o n and use of a l t e r n a t i v e energy sources. A r e p o r t by S i e d a l and Keyes (1983) f o r the U.S. Environmental P r o t e c t i o n Agency, examined the probable impact of v a r i o u s world-wide taxes and bans. They found t h a t o n l y a ban on c o a l i n s t i t u t e d by 2000, would d e l a y a 2°C change i n GAST u n t i l 2055 (without any a c t i o n , the authors estimate t h i s change w i l l occur by 2040). World-wide taxes of up to 300% o f the c o s t of f o s s i l f u e l s were estimated to have l i t t l e e f f e c t on t h e i r use. Such methods, as w e l l as being p o t e n t i a l l y i n e f f e c t u a l , c o u l d cause h a r d s h i p e s p e c i a l l y i n d e v e l o p i n g c o u n t r i e s . (f) Another means of p r e v e n t i n g the b u i l d - u p of atmospheric carbon d i o x i d e i s to i n c r e a s e the biomass. P l a n t i n g enough t r e e s to keep up with the s t e a d i l y growing use of f o s s i l f u e l s , would be d i f f i c u l t , even i f there were enough land f o r a l l the t r e e s ( K e l l o g g and Schware, 1981). In summary, many a n a l y s t s b e l i e v e the p r e v e n t i o n of an i n c r e a s e i n atmospheric carbon d i o x i d e i s a seemingly u n a t t a i n a b l e g o a l , g i v e n the problems o f unknown t e c h n o l o g i e s , timing and i n t e r n a t i o n a l c o o p e r a t i o n . 5.3 What S t r a t e g i e s are A p p r o p r i a t e f o r an Unstable Climate?  At p r e s e n t , land and r e s o u r c e s have g e n e r a l l y been oc c u p i e d , c u l t i v a t e d and developed i n the b e l i e f t h a t the c l i m a t i c system i s f a i r l y s t a b l e . T i c k e l l (1978) observes that people e r r o n e o u s l y p e r c e i v e the swings of c l i m a t e they have 122 observed during t h e i r l i f e t i m e s as the extremes of c l i m a t i c v a r i a b i l i t y . Such an assumption of s t a b i l i t y " i n v i t e s p l a n n i n g f o r the optimum, and planning f o r the optimum lead s to maximum e x p l o i t a t i o n of land and r e s o u r c e s .... Provided t h a t s t a b i l i t y i s maintained, the [human systems] should work with i n c r e a s i n g e f f i c i e n c y as improvements are c o n s t a n t l y made to [them] .... But the moment the environment changes, [the human systems] best adapted to i t s u f f e r most and have the g r e a t e s t d i f f i c u l t y i n a d j u s t i n g themselves" (p. 44). Based on the assumption o f c l i m a t i c s t a b i l i t y , human systems have been designed t h a t attempt to be e q u a l l y s t a b l e . To do t h i s s o c i e t y t r i e s to c o n t r o l or remove the f l u c t u a t i o n s of the environment i n an attempt to maximize p r o d u c t i v i t y and p r e d i c t a b i l i t y . For example, F i g u r e 33 i l l u s t r a t e s a t y p i c a l time p r o f i l e of a g r i c u l t u r a l p r o d u c t i o n under v a r y i n g c l i m a t i c c o n d i t i o n s . Crop s u r p l u s e s and d e f i c i t s are u s u a l l y not d e s i r a b l e so s o c i e t y s t r i v e s to s t a b i l i z e p r o d u c t i o n through mechanization, h e r b i c i d e s , p e s t i c i d e s , f e r t i l i z e r s , g e n e t i c m a n i p u l a t i o n of c r o p s , i r r i g a t i o n and o t h e r management techniques. S o c i e t y s t r i v e s f o r p r e d i c t a b l e , p r o f i t - m a x i m i z i n g y i e l d as shown i n Figure 34. S i m i l a r l y , the e f f o r t s to manage and develop o t h e r human systems have a l s o been d i r e c t e d a t a s s u r i n g the systems are r e l i a b l e and f u n c t i o n smoothly. In c o n t r a s t , Cooper (1982) suggests the systems we c r e a t e need t o a n t i c i p a t e , respond and adapt to n a t u r a l d i s r u p t i o n s and f l u c t u a t i o n s r a t h e r than p r o t e c t themselves from 123 FIGURE 33: Crop y i e l d s showing and t y p i c a l s u r p l u s e s and bad y e a r s . p r o f i t m a x i m i z i n g y i e l d , and d e f i c i t s d u r i n g good 124 YIELD TIME-FIGURE 3-4: Through t e c h n o l o g y and management t e c h n i q u e s s o c i e t y s t r i v e s t o produce the p r o f i t m a x i m i z i n g y i e l d and d e l e t e s u r p l u s e s and d e f i c i t s . 125 these c e r t a i n changes. At present, Cooper argues, our systems are h i g h l y v u l n e r a b l e or " l i k e l y to r e a c t a d v e r s e l y to new c o n d i t i o n s " and need to be made more r e s i l i e n t o r ab l e to " r e a c t to new c o n d i t i o n s without s h i f t i n g to a q u a l i t a t i v e l y d i f f e r e n t s t a b l e s t a t e " (p. 299). Adaptive management of human systems i s t h e r e f o r e designed to i n c r e a s e t h e i r r e s i l i e n c y so these systems can a d j u s t to changing c l i m a t i c c o n d i t i o n s , t a k i n g advantage o f p o s i t i v e e f f e c t s and minimizing negative ones. Such f l e x i b l e management all o w s human systems not onl y to s u r v i v e changing c l i m a t i c c o n d i t i o n s , but to take advantage of them. Ad a p t a t i o n does not c a l l f o r a sudden massive input o f funds t o a l t e r management techniques or b u i l d new r e s e r v o i r s , c a n a l s o r o t h e r s t r u c t u r e s . Rather adaptive s t r a t e g i e s suggest contingency p l a n n i n g , m o n i t o r i n g changes and r a t e o f change, a p e r i o d i c r e - e v a l u a t i o n o f management p o l i c i e s i n l i g h t o f new i n f o r m a t i o n from r e s e a r c h and monitoring and the d i s s e m i n a t i o n of i n f o r m a t i o n l i k e l y to a i d i n the implementation o f contingency plans as and when they become needed. 5.4 Can the Systems be Made More R e s i l i e n t ? C r e a t i n g r e s i l i e n t systems i s d i f f i c u l t because the necessary s t r a t e g i e s may not be the most e f f i c i e n t o r c o s t -e f f e c t i v e i n the s h o r t term. In a d d i t i o n , managers are not able to s t a r t with a c l e a n s l a t e : human systems such as 126 t r a n s p o r t a t i o n p a t t e r n s , s e t t l e m e n t p a t t e r n s or a g r i c u l t u r a l p r a c t i c e s are w e l l e s t a b l i s h e d . Despite these impediments s t r a t e g i e s have been developed and i n i t i a t e d t h a t help to make the systems i n v o l v e d more r e s i l i e n t to the kind of changes t h a t can be a n t i c i p a t e d . For example, the B r i t i s h Columbia M i n i s t r y of Environment encourages m u n i c i p a l i t i e s to r e c o g n i z e the behaviour of r i v e r systems by o n l y - p e r m i t t i n g development on f l o o d p l a i n s t h a t r e s p e c t s the p o s s i b i l i t y of f l o o d i n g through adequate f l o o d - p r o o f i n g or by encouraging land uses that can withstand f l o o d i n g (Doughty-Davis, 1976). Other s t r a t e g i e s t h a t c o u l d i n c r e a s e r e s i l i e n c e i n c l u d e : (a) Developing r e s e r v e s - Reserves of energy, food and water, s t o r e d during "good" years c o u l d p r o v i d e f o r "bad" y e a r s . Schneider and Mesirow (1976) r e f e r to t h i s as the Genesis St r a t e g y i n r e f e r e n c e to the s t o r y i n the Old Testament about the Egyptian Pharoah who saved h i s people by s t o r i n g g r a i n f o r the l e a n y e a r s . Reserves not o n l y a c t as b u f f e r s d u r i n g bad y e ars but a l s o "buy time" i n which to determine lo n g e r term responses to c l i m a t i c change. P r o v i d i n g such m a r g i n s - o f - s a f e t y i s o f t e n r e s i s t e d by producers and d i s t r i b u t o r s because l a r g e r e s e r v e s tend to s t a b i l i z e market p r i c e s and thereby remove the p r o f i t i n c e n t i v e s (Schneider and Mesirow, 1976). E f f e c t i v e l y , there are no l o n g e r any s u r p l u s e s or d e f i c i t s on the market because one year's s u r p l u s f i l l s another year's d e f i c i t s . Reserves a l s o p r o v i d e a s t a b l e income f o r those i n v o l v e d i n the a c t i v i t y . 127 (b) D i v e r s i f y i n g a c t i v i t i e s - H o l l i n g and Goldberg (1971) p o i n t out th a t any a c t i o n taken w i l l most l i k e l y have unexpected, perhaps u n d e s i r a b l e consequences. By widening the range of food sources, t r a n s p o r t a t i o n o p t i o n s and energy sour c e s , s o c i e t y i s l e s s l i a b l e to experience enormous upheaval i f one p a r t i c u l a r source or o p t i o n f a i l s f o r any reason. Through d i v e r s i f i c a t o n , the odds are b e t t e r t h a t the food o r energy sources o r t r a n s p o r t a t i o n modes th a t respond w e l l t o , or at l e a s t s u r v i v e , c l i m a t i c change w i l l be i n e x i s t e n c e . Schneider and Mesirow (1976) note t h a t there i s o f t e n a t r a d e - o f f made between e f f i c i e n c y and d i v e r s i t y t h a t i n v o l v e s an economic c o s t . Present economic thought i s d i r e c t e d a t c o s t -e f f e c t i v e , e f f i c i e n t p r o d u c t i o n which u s u a l l y i n v o l v e s one crop type i n s t e a d o f many d i v e r s e ones, one supertanker r a t h e r than many s m a l l e r s h i p s and a few l a r g e manufacturing p l a n t s r a t h e r than many d i v e r s e ones. D i v e r s i t y can be c o s t l y but as Schneider and Mesirow (1976) emphasize, choosing e f f i c i e n c y over d i v e r s i t y a l s o i n v o l v e s a t r a d e - o f f between present c o s t s and f u t u r e p o s s i b l e c a t a s t r o p h i c c o s t s . 5.5 What I n t e r n a t i o n a l S t r a t e g i e s can be Adopted? Because the carbon d i o x i d e - i n d u c e d warming i s a g l o b a l concern, i n t e r n a t i o n a l c o o p e r a t i o n i s needed. Schneider and Mesirow (1976) suggest the need f o r f o u r new i n t e r n a t i o n a l i n s t i t u t e s : (a) The I n s t i t u t e of Imminent D i s a s t e r s would be a m u l t i d i s c i p l i n a r y , i n t e r n a t i o n a l group s e t up to forewarn, study 128 and i d e n t i f y p o t e n t i a l dangers to world s e c u r i t y . This group would assess the c o s t s , l i k e l i h o o d and timing o f impending d i s a s t e r s . I n s t i t u t e members would shed t h e i r advocacy r o l e s and work together to p r o v i d e c l e a r and comprehensive i n f o r m a t i o n f o r decision-makers, and d i r e c t the r e s e a r c h of the o t h e r i n s t i t u t i o n s . (b) The I n s t i t u t e of Resource A v a i l a b i l i t y would p r o v i d e independent resource data on such i s s u e s as world food p r o d u c t i o n , world energy supply, demographic world t r e n d s , worldwide carbon d i o x i d e r e l e a s e , f e r t i l i z e r and c h l o r o f l u o r o -carbon use, c h l o r i n a t i o n of water, energy use and growth r a t e s . The energy " c r i s i s " of 1973-4 showed the need f o r such i n f o r m a t i o n . Was there a resource shortage or a mismanagement of s u p p l i e r s or even a d e l i b e r a t e c o n s p i r a c y to d r i v e up p r i c e s ? Information on s u p p l i e s , r e s e r v e s , p r o d u c t i o n , e t c . was not a v a i l a b l e i n order to answer these q u e s t i o n s . In the case of a carbon d i o x i d e - i n d u c e d warming such an i n s t i t u t e c o u l d p r o v i d e data on carbon d i o x i d e emissions by country, r a t e s of i n c r e a s e , and probable t r e n d s . (c) The I n s t i t u t e of P o l i c y Options would develop p o l i c y o p t i o n s based on the i n f o r m a t i o n gathered from the three o t h e r i n s t i t u t e s . Environmental, p o l i t i c a l , economic and s o c i a l aspects of the v a r i o u s p o l i c y o p t i o n s would be e v a l u a t e d by t h i s I n s t i t u t e based on i n f o r m a t i o n s u p p l i e d by the o t h e r I n s t i t u t e s . (d) The I n s t i t u t e of A l t e r n a t i v e Technologies would e v a l u a t e and promote the development of supplementary, 129 a l t e r n a t i v e or replacement t e c h n o l o g i e s . Energy sources t h a t do not emit carbon d i o x i d e would be developed and t e s t e d by t h i s I n s t i t u t e . Because the i n t e n t of these i n s t i t u t e s i s to i n c r e a s e long-term g l o b a l r e s i l i e n c y and a d a p t a b i l i t y , there a c t i o n s may be a t odds with i n d i v i d u a l n a t i o n s more i n t e r e s t e d i n short-term growth or development. At p r e s e n t , p r i c i n g and trade i s based to a l a r g e e x t e n t on r e a l or p e r c e i v e d s c a r c i t y . O i l producing n a t i o n s , f o r example, would not be i n t e r e s t e d i n d i v u l g i n g i n f o r m a t i o n about t h e i r s u p p l i e s , r e s e r v e s or p r o d u c t i o n , i f t h i s i n f o r m a t i o n r e v e a l s there i s not s c a r c i t y of r e s e r v e s o r s u p p l i e s . Major s h i f t s i n economic thought and o t h e r a t t i t u d e s would be necessary i n o r d e r f o r the f o u r i n s t i t u t e s to be s u c c e s s f u l . Enormous s o c i a l , economic and environmental upheaval, perhaps due to atmospheric carbon d i o x i d e may be necessary before n a t i o n s r e a l i z e the need to work tog e t h e r i n the c o l l e c t i v e i n t e r e s t s of a l l n a t i o n s . Thus while the elements and importance of an i n t e r n a t i o n a l s t r a t e g y have been r e c o g n i z e d , i t s implementation i s not going to be easy. The r e c e n t experiences at IIASA, a comparable but l e s s ambitious attempt to undertake such s t u d i e s , i l l u s t r a t e the very g r e a t d i f f i c u l t y of r e c e i v i n g i n t e r n a t i o n a l c o o p e r a t i o n f o r such endeavours ( R a i f f a , 1982). In l i g h t of these d i f f i c u l t i e s , i t would appear the most e f f e c t i v e s t r a t e g i e s , a t l e a s t f o r the immediate decades, i n v o l v e m o n i t o r i n g , r e s e a r c h and the development of contingency 130 plans and a d a p t i v e s t r a t e g i e s . These s t r a t e g i e s r e q u i r e the l e a s t marginal e f f o r t a t the p r e s e n t time (Meyer-Abich, 1980) and a l l o w i n d i v i d u a l c o u n t r i e s who may b e n e f i t from a g l o b a l warming to take advantage of any p o s i t i v e e f f e c t s . 5.6 What s t r a t e g i e s can be I n i t i a t e d i n the Vancouver area L i t t l e can be done at the r e g i o n a l l e v e l to prevent the b u i l d - u p of atmospheric carbon d i o x i d e . Unless g l o b a l i n s c a l e , any p r e v e n t i v e a c t i o n would be g e n e r a l l y i n e f f e c t i v e . In most cases, s t r a t e g i e s must be designed a t the i n t e r n a t i o n a l o r n a t i o n a l l e v e l a f t e r an a n a l y s i s of the r e g i o n a l impacts and a p r i o r i t i z i n g of where a c t i o n i s most needed. Regional governments need to be aware of any n a t i o n a l and i n t e r n a t i o n a l i n i t i a t i v e s i n o r d e r to determine how they may c o n t r i b u t e to them. There are some r e s e a r c h monitoring and contingency planning s t r a t e g i e s t h a t can be implemented i n the Vancouver area to help the n a t i o n a l and i n t e r n a t i o n a l s t r a t e g i e s and to ensure the human systems are made more r e s i l i e n t to change. These s t r a t e g i e s are o u t l i n e d below and are p r i o r i z e d a c c o r d i n g to the ranking of impacts i n the p r e v i o u s chapter. Most of these s t r a t e g i e s i n v o l v e contingency planning which i n t u r n o f t e n p o i n t s to areas where r e s e a r c h i s needed. (1) S t r a t e g i e s to d e a l with severe impacts: 131 Sea L e v e l R i s e ; (a) The c o s t s and b e n e f i t s a s s o c i a t e d with a d d i t i o n a l dyking o r evac u a t i o n and r e s e t t l e m e n t r e q u i r e f u r t h e r a n a l y s i s . The a n a l y s i s i n t h i s t h e s i s i s not e x t e n s i v e and i s based p r i m a r i l y on one s c e n a r i o of sea l e v e l r i s e and a gr a d u a l r a t e o f change and a l s o assumed there w i l l be s u f f i c i e n t time i n which to respond to r i s i n g sea l e v e l s . Other s c e n a r i o s should be examined and the a s s o c i a t e d c o s t s and b e n e f i t s o f dyking and eva c u a t i o n s t u d i e d i n more d e t a i l . In p a r t i c u l a r , the f o l l o w i n g r e q u i r e more a n a l y s i s i n o r d e r t o more c a r e f u l l y c a l c u l a t e a b e n e f i t / c o s t r a t i o : ( i ) the f e a s i b i l i t y o f r a i s i n g e x i s t i n g dykes; ( i i ) the c o s t s of r a i s i n g dykes i n c l u d i n g c o s t s of e x p r o p r i a t i o n o f l a n d ; and ( i i i ) the va l u e o f a l l improvements t h a t may be damaged or made unusable by a 1 to 5 metre r i s e i n sea l e v e l . ( i v ) the time necessary to c o n s t r u c t a d d i t i o n a l dyking. (b) F u r t h e r development i n the e x i s t i n g f l o o d p l a i n and l o w - l y i n g c o a s t a l areas p r e s e n t l y p r o t e c t e d by dykes could be disco u r a g e d u n t i l such time as the extent and r a t e o f sea l e v e l r i s e i s b e t t e r understood and can be a c c u r a t e l y mapped. When the extent of i n u n d a t i o n i s determined, development can proceed i n some areas a c c o r d i n g to e x i s t i n g f l o o d p l a i n l e g i s l a t i o n . Sea l e v e l r i s e r e i n f o r c e s the va l u e o f e x i s t i n g f l o o d p l a i n l e g i s l a t i o n and p o l i c i e s . 132 (c) An a n a l y s i s of areas b e s t s u i t e d t o human set t l e m e n t i n l i g h t of p r o j e c t e d sea l e v e l . r i s e s , i n c r e a s e d r u n o f f , p o s s i b l e i n c r e a s e i n value of a g r i c u l t u r a l l a n d , i n c r e a s e d ozone l e v e l s and i n c r e a s e d i n c i d e n c e s of fog, should be undertaken. F i n d i n g a c c e p t a b l e means of i n c r e a s i n g d e n s i t y i n s u i t a b l e areas t h a t are p r e s e n t l y developed w i l l become i n c r e a s i n g l y important. (d) Means of compensating and p r o v i d i n g f o r human settlement d e t r i m e n t a l l y a f f e c t e d by a carbon d i o x i d e - i n d u c e d warming need to be i n v e s t i g a t e d . At pr e s e n t , p r o v i n c i a l a i d to v i c t i m s of f l o o d s i s done on an ad hoc b a s i s by O r d e r - i n - C o u n c i l . (2) S t r a t e g i e s to d e a l with important impacts: A g r i c u l t u r e (a) A more complete a n a l y s i s of the impacts of a carbon d i o x i d e - i n d u c e d warming on areas from which we import c r o p s , such as C a l i f o r n i a , can be undertaken. Understanding how these areas w i l l be a f f e c t e d w i l l g i v e a b e t t e r idea of the f u t u r e r o l e o f a g r i c u l t u r e i n the Vancouver area. (b) Crops t h a t w i l l b e n e f i t from a carbon d i o x i d e -induced warming need to be i d e n t i f i e d . Experiments with types and v a r i e t i e s of crops not p r e s e n t l y grown i n the Vancouver area can be undertaken to determine t h e i r response t o e l e v a t e d carbon d i o x i d e l e v e l s i n the atmosphere. (c) A d d i t i o n a l a c t i v i t i e s to can, dry and f r e e z e l o c a l produce should be i n v e s t i g a t e d and o t h e r methods of p r e s e r v i n g 133 s u r p l u s e s examined i n o r d e r to guarantee c o n t i n u i t y of supply and to be c o m p e t i t i v e i n the marketplace a g a i n s t r e l a t i v e l y i n e x p e n s i v e imports, and to ensure s u p p l i e s when c l i m a t e v a r i e s . (d) Means of m a i n t a i n i n g the p r e s e n t d i v e r s i t y of crop types i n the Vancouver area need to be examined. Although there i s p r e s e n t l y a f a i r amount o f d i v e r s i t y of crop types and f i e l d s are g e n e r a l l y small i n the Vancouver area (B.C. M i n i s t r y o f A g r i c u l t u r e and Food and DREE, 1980) , there are economic p r e s s u r e s t h a t are d i s c o u r a g i n g d i v e r s i t y . P r o d u c t i o n of a few crop types on l a r g e f i e l d s tends to be e c o n o m i c a l l y a t t r a c t i v e because p l a n t i n g , h a r v e s t i n g , ploughing, e t c . can be done at one time of year with l a r g e machinery. Runoff C o n d i t i o n s : « (a) Present drainage f a c i l i t i e s r e q u i r e re-examination i n l i g h t of p o s s i b l e changes, to determine t h e i r adequacy. P a r t i c u l a r l y i n North and West Vancouver, drainage systems may become i n c r e a s i n g l y inadequate. (3) S t r a t e g i e s to d e a l with minor impacts: Water Supply System: (a) The c o n s t r u c t i o n of a d d i t i o n a l s torage f a c i l i t i e s may be necessary and the f e a s i b i l i t y and c o s t s i n v o l v e d should be e s t i m a t e d . Other a l t e r n a t i v e s to c o n s i d e r would be water r a t i o n i n g or metering. 134 (b) With i n c r e a s e d temperatures, a d d i t i o n a l a e r a t i o n and c h l o r i n a t i o n of the water may become necessary. Plans should be made to i n t r o d u c e f u r t h e r treatment when necessary. Fog C o n d i t i o n s : (a) In order to d e a l with i n c r e a s i n g i n c i d e n c e s o f fo g , s t r i c t e r c o n t r o l s t o f u r t h e r reduce emission o f condensation n u c l e i may be necessary e s p e c i a l l y d u r i n g f o g -s u s c e p t i b l e times. A fog warning system may become necessary, p r o v i d i n g warning of weather c o n d i t i o n s l i k e l y to cause fog. Mandatory fog l i g h t s on motor v e h i c l e s may become necessary. Contingency plans i n c o r p o r a t i n g the above c o n t r o l s can be drawn up and i n t r o d u c e d when necessary. P o l l u t i o n C o n d i t i o n s : (a) S t r i c t e r c o n t r o l o f f o s s i l f u e l e m i s s i o n s , t r a n s f e r and storage o f f u e l and o f hydrocarbon-based p a i n t s and ot h e r m a t e r i a l s may become necessary to c o n t r o l ozone l e v e l s . Zoning to discourage development i n ozone-prone areas may be d e s i r a b l e . I f c o n d i t i o n s are severe enough, a smog a d v i s o r y system such as e x i s t s i n San F r a n c i s c o (Bay Area P o l l u t i o n C o n t r o l D i s t r i c t , 1974) may be necessary. The a d v i s o r y system i n San F r a n c i s c o warns of c o n d i t i o n s t h a t may be harmful to people with r e s p i r a t o r y problems and as c o n d i t i o n s worsen, c a l l s f o r the shutdown of c e r t a i n o f f i c e s , p l a n t s and s c h o o l s t o reduce commuter t r a f f i c . 135 Other s t r a t e g i e s t h a t can be taken i n the Vancouver ar e a i n c l u d e : (a) a c o n t i n u i n g review and s y n t h e s i s o f the growing body of l i t e r a t u r e concerning the carbon d i o x i d e i s s u e . Research developments are t a k i n g p l a c e r a p i d l y and there i s a need to "take stock" p e r i o d i c a l l y and to p r o v i d e d i r e c t i o n f o r f u r t h e r r e s e a r c h . In a d d i t i o n , r e s e a r c h undertaken elsewhere may be p a r t i c u l a r l y r e l e v a n t to the Vancouver area. For example, the l i t e r a t u r e should be c a r e f u l l y reviewed t o determine i f r e s e a r c h i s being undertaking concerning the impact of a g l o b a l warming on a g r i c u l t u r e i n C a l i f o r n i a and o t h e r areas from which crops are imported. (b) M o n i t o r i n g o f c l i m a t e parameters and changes i n human systems i n the Vancouver a r e a , i n o r d e r to determine when contingency plans should be i n t r o d u c e d . Many needed parameters such as p r e c i p i t a t i o n , temperature, ozone or fog l e v e l s are now monitored c a r e f u l l y ; o t h e r s such as f l u c t u a t i o n s i n ocean temperature, crop y i e l d o r r u n o f f may r e q u i r e c l o s e r m o n i t o r i n g . For example i n c r e a s e d r a i n f a l l and i n c r e a s e d storm i n t e n s i t y may r e s u l t i n more fre q u e n t d e b r i s flow events on t r a n s p o r t a t i o n c o r r i d o r s . Such events should be monitored and contingency plans f o r t h e i r c o n t r o l i n t r o d u c e d when necessary. 5.7 C o n c l u s i o n : Where to Now? The s t r a t e g i e s t h a t can be implemented i n the Vancouver ar e a i n a n t i c i p a t i o n of a carbon d i o x i d e - i n d u c e d g l o b a l 136 warming, appear small and i n s i g n i f i c a n t in l i g h t of the enormity of the possible impacts. However, these strategies may be very important in the long term. Revelle (1982) emphasizes that s o c i e t i e s have had experience responding to short-term events such as hurricanes, floods, droughts, volcanic eruptions, earthquakes, and forest f i r e s . However, change due to a carbon dioxide-induced global warming w i l l be very d i f f e r e n t than these sudden "events; rather change w i l l be slow and pervasive, and w i l l be "imperceptible to most people from year to year because of the annual range of c l i m a t i c v a r i a t i o n " (p. 43). By i n i t i a t i n g contingency planning and monitoring strategies now, the Vancouver area w i l l be in a state of preparedness, with adaptive management strategies and r e s i l i e n t human systems i n place, changing conditions whether they be due to a carbon dioxide-induced warming or other, as yet unknown factors. In the Vancouver area immediate attention should be focussed on the following issues: F i r s t , a further evaluation of the hazards due to sea l e v e l r i s e and an analysis of the possible responses including a d d i t i o n a l dyke construction and evacuation and resettlement i s needed. Second, a further evaluation of the impacts on agriculture in the Fraser Valley, and p a r t i c u l a r l y how the impacts in areas such as C a l i f o r n i a may a f f e c t Vancouver, i s needed. 137 T h i r d , f u r t h e r r e s e a r c h i s necessary to r e v e a l the e x t e n t and magnitude of o t h e r impacts not analyzed i n t h i s t h e s i s such as the impacts on f o r e s t r y , the f i s h e r i e s , w i l d l i f e , and i n f r a s t r u c t u r e such as sewage d i s p o s a l and treatment p l a n t s and t r a n s p o r t a t i o n c o r r i d o r s . As w e l l a more d e t a i l e d a n a l y s i s o f the p o s s i b l e p o s i t i v e impacts o f a carbon d i o x i d e - i n d u c e d warming i s necessary. Most r e s e a r c h focusses on the d i s r u p t i v e o r negative i m p l i c a t i o n s but the means of t a k i n g advantage of p o s i t i v e e f f e c t s a l s o r e q u i r e study. F i n a l l y , a c t i o n s r e q u i r e p u b l i c support i f they are to be i n i t i a t e d and e f f e c t i v e . At p r e s e n t there i s a g r e a t d e a l of m i s i n f o r m a t i o n and s e n s a t i o n a l i s m surrounding the carbon d i o x i d e i s s u e . A p u b l i c e d u c a t i o n program i s r e q u i r e d to develop an understanding of the p o s s i b l e outcomes, to b u i l d consensus on what should be done and to p r o v i d e support f o r a c t i o n s t h a t are i n i t i a t e d . An a u t h o r i t y i s r e q u i r e d to ensure the necessary s t e p s are taken to i n i t i a t e these a c t i o n s and to ensure a thorough and c o o r d i n a t e d e f f o r t . 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