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CANADA: SPECIAL REPORT
THE GLOBAL WARMING CHALLENGE Understanding and Coping with Climate Change in Canada anada is the world's seco n d largest c o u n t r y , with 10 million square kilometers of territory bounded by three oceans. Its large size and extensive coastlines expose the country to many different climate regimes, from the rain forests ofthe west coast to the dry prairies in the interior and the frozen expanses of the north ( 1 ) . Years of experience in coping with these varied couditions have helped Canadians develop a social and economic structure that is well adapted to the realities of their climate as we knnw it today. It is not surprising, therefore, that Caoadians have a profound interest in climate change and, particularly, global warming. Global warming, for example, could improve the growing seasons for certain ecosystems and destroy others with fire and drought. It could open u p our ice-congested Arctic waters to increased shipping and cause the collapse of surface transportation systems over permanently frozen lands. The exact consequences of global warming are uncertain, of course, but one thing is clear: global warming will necessitate significant adjustments in Canadian society and its economy. A national climate program For decades, Canada has recog-
nized the importance of monitoring its diverse and variable climate. The nation maintains a central archive of climate data collected from a country-wide network of monitoring stations at more than 2000 locations; some stations have been in
place siuce the mid-19th century. The resultant information, which builds understanding of the past behavior of climate, provides an important basis both for designing our i:ountry's infrastructure and for planniog our socioeconomic activities. Although knowledge of past patterns has helped Canadians to increase the compatibility of Canada's culture with its ambient climate, that focus alone is not enough. The 1970s brought a range of unusual weather events that woke the entire world to the importance of factoring climate variability into decision making. Episodes of extreme cold, droughts, floods, and other climateinduced hazards resulted in extensive crop failures, food shortages, price inflation, and hunger in other parts of the world. In particular, these events raised questions about the reliability of using past climate as an indicator of future climate. Conferences sponsored by agencies of the United Nations began to focus on the causes and consequences of unusual climate events. Finally, in 1979, the First World Climate Conference held in Geneva laid the groundwork for the establishment of the World Climate Programme. In the same year, the Canadian federal government created its own Canadian Climate Program (CCP) in collaboration with other agencies, institutions, and individuals. It
HENRY HENGEVELD Environment Canada Downsview, ON, Canada M3H 5T4
0013-936X/94/0927~519A$04.50100 1994 American Chemical Society
sought to coordinate national efforts to understand global and regional climate, and to promote better use of the emerging knowledge. Its original objectives, which remain relevant today, were t u develop the ability to predict climate and climate change; assess the impact of human activities on climate; improve the use of climate infurmation in Canada's economy; and through the World Climate Programme, assist developing countries in improving their use of climate information (2). 'The CCP is administered by a national Climate Program Board, which includes representatives from federal agencies, provincial governments, universities, and the private sector. A number of advisory committees and subgroups assist with program coordination, including the National Climate Advisory Committee on Data and Applications, the Research Advisory Committee, and the Socio-Economic Impacts Committee. This collaboration between agencies and scientists is vital to the program.
Climate change research Growing international concerns about global warming have highlighted the need to better understand the global geophysical syst e m , i n c l u d i n g t h e processes governing the natural cycles of greenhouse gases and the global climate system. Hence climate system research and investigations into the fluxes of greenhouse gases between the atmosphere and the vast Canadian terrestrial ecosystems and ad-
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Canadian GCM projections of seasonal climate warming under a doubling of atmospheric C02
jacent oceans have become key focal points of the CCP. Much of the CCP-coordinated research into sources and sinks of greenhouse gases interfaces with other national and international programs. Many of the investigations into carbon fluxes i n the oceans, for example, are conducted within the framework of the international Joint Global Ocean Flux Study, which is aimed at understanding the role of the ocean in the global carbon cycle (3). Other researchers have become involved in the Northern Wetlands Study, a cooperative United StatesCanada initiative to understand the role of huge northern bogs and muskegs in the carbon cycle (4).Results from these studies show that net methane emissions from wetlands adjacent to Hudson Bay are an order of magnitude smaller than would be expected from previous estimates based on studies in peat lands further south. Emissions were found to be highly sensitive to depth of water tables (5, 6). The low methane fluxes from northern wetlands are likely the result of ecosystem and physiological controls of methane production and consumption (7). Likewise, carbon fluxes in forests are a focus of current interdisciplinary projects such as the Boreal Ecosystems-Atmosphere Study and the Northern Biosphere Observation and Modelling Experiment. Preliminary results from these and other
studies suggest that Canadian boreal forests provide a net sink for carbon dioxide, after allowing for effects of wildfires, insect-induced mortality, and harvesting, of about 100 Mt of carbon per year. Investi-
GLOBAL WARMING WOULD NECESSITATE SIGNIFICANT ADJUSTMENTS IN C A N A D I A SOCIETY A N ITS ECONOMY
gators suggest this carbon sink exists urimarilv because these forests are still in a process of aging and hence increasing their store of carbon within the standing biomass and litter. However, as tKe forests mature, this sink will likely disap-
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pear. Furthermore, if warmer and possibly drier climates develop in the decades to come, as projected by climate model experiments, increased intensity and frequency of fire and insect disturbances could turn the boreal forests into a significant source of carbon dioxide (8). Modeling studies to explore climate-carbon cycle linkages are now in progress. Meanwhile, research programs within Canada’s agricultural community include investigations i n t o related greenhouse sources and sinks from this sector. Results from Canadian studies into climate system processes have made similar contributions to understanding the Earths climate system (9-12).However, the challenge is formidable. The total global climate system involves not only a dynamic and chemically active atmosphere, but also circulating oceans, advancing and retreating ice sheets, and changing vegetation patterns. In real life, these components are coupled in an intricate and interactive manner that involves complex feedbacks. Researchers are still uncertain about how the various climate processes behave under stable climate conditions, let alone how they respond to large changes in one or more comvonents. General circulation models Because of the need to understand how the whole, linked climate system works, climate model-
ing emerged as a key focus of current research. Within Canada, modeling began in earnest in the mid-1970s with the establishment of a small group of climate modelers within Environment Canada’s Atmospheric Environment Service (AES). By the late 1980s, the AES group had developed a second-generation, high-resolution General Circulation Model (GCM) of the climate system. This model is now generally accepted as one of the world’s more advanced models for assessing global climate change caused by an equilibrium response to a doubling of atmospheric carbon dioxide Concentrations; that is, it illustrates how the Earth’s climate might function once it has adjusted to a carbon dioxide doubling. The atmospheric modeling group is currently cooperating with oceanographers to develop a third-generation GCM with a fully coupled ocean-atmosphere climate system. This model will build on the successful foundation provided by the AES second-generation model by incorporating improvements to many of its present features while adding important new capabilities. Results of future experiments with this model will help provide new and unique insights into the international understanding of the role of various climate system feedbacks i n amplifying or attenuating change, and of the transient response of the total climate system to forces of change as they happen (13).
Improvements being incorporated into the model include better understanding of how cloud processes affect climate; improved characterization of soil and vegetation properties at the atmosphere-land interface: a n d a more sophisticated treatment of processes taking place in the middle atmosphere (up to 85 km above the Earth’s surface), particularly with respect to chemical interactions between trace gases and their effects on the Earth’s radiative budget and atmospheric circulation. With the aid of Environment Canada’s supercomputer in Victoria, these changes will allow more realistic simulations of the Earth’s gradual response to slowly changing atmospheric conditions, including the effects of changing ocean circulation as a feedback to global warming. Researchers are also developing regional models that expand upon the output of the relatively low-resolution GCMs ( 2 ) . These regional
models use the output of the global GCMs as inputs for the boundary conditions of the changing climate within the region, but can simulate local characteristics and small-scale processes of the climate within the region with much greater accuracy and detail. The results provide a description of the local characteristics of climate change that is more suitable for use in assessment of ecological and socioeconomic impacts, without being limited by inadequate computing power. However, the accuracy of results continues to be limited by uncertainties in the boundary conditions provided by the global GCMs. A substantial increase in central funding since 1991 has helped stimulate and focus this research nationally. To further support GCM modeling and conduct related research, Canada is now developing a joint university-government-industry Climate Research Network ( 2 ) . Research groups across the country will each focus on a particular area, and a high-speed data link will connect the groups to each other and to the modeling group and its supercomputer. The network, with the GCM research as its focal point, contributes substantially to the international research effort, while providing Canada with a well-coordinated base of expertise for assessing the country’s vulnerability to the risks of climate change and formulating appropriate policy responses. Key network research nodes will include ocean circulation modeling (Victoria and Montr e a l ) , a t m o s p h e r i c chemistry (Toronto), clouds (Toronto), paleoclimate (Ottawa), land surface processes (Saskatoon), and regional climate modeling (Montreal).
Preparing for climate change Applied climatology helps Canadians deal with the constraints imposed by local climate, while capitalizing on the opportunities that it provides. However, cultures in harmony with their climate can be more vulnerable to climate change; anticipation of change and preparation for it become extremely important. Unfortunately, it is still impossible to accurately forecast how climate will change. Prediction is especially uncertain for those climate characteristics of greatest importance in strategic planning, such as the rate at which changes will occur; the geographical patterns of changes in temperature and precip-
itation: a n d the frequencies of storms,, droughts, severe hot or cold spells, and other extreme events. However, models that project how climate will respond to increasing greenhouse gas concentrations can already provide some clues. The models can indicate the direction such changes may take and can help test the sensitivity of ecosystems and socioeconomic activities to a range of possible changes. In the past decade, many studies have explored the impacts of past climate fluctuations and extreme events on Canadian ecosystems and society, and have helped to assess Canada’s vulnerability to the effects of possible future changes ( 2 4 , 25). The studies have involved a wide range of methods, ranging from simple empirical investigations into the consequences of a historical event to sophisticated analyses of the effect of a range of possible climate change scenarios (“what if” case studies) on integrated systems. Studies make extensive use of advanced models, developed from analysis of past experience, which describe the climate-ecosystemsociety linkages, including crop growth models, hydrological models, forest fire models, total ecosystem models, and models of socioeconomic response to change. Results of the studies, many of which are regularly summarized in the Climate Program Board’s series of “Climate Change Digest” reports ( 2 6), are both encouraging and worrisome (see box). Many Canadian ecosystem processes and society activities are currently limited more by cold-temperature extremes than by warm extremes. Hence, many aspects of the impacts of warmer temperatures are potentially beneficial, providing Canadian ecosystems and society can adapt quickly enough. This is not valid, however, for systems that have long lifetimes and hence respond slowly to change (e.g., forest ecosystems), or for activities that depend on cold climates (e.g., winter sports and winter Arctic transportation). On the other hand, many of the implications of climate change impacts on water resources are problematic, particularly in the interior of Canada. In some cases, adaptation will be difficult, and major negative residual effects unavoidable.
Earlier data are meaningful In 1 9 9 1 , the Climate Program Board’s Socio-Economic Impacts Committee recommended that, in
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Projected changes in Canadian ecozones as a result of doubling of atmospheric C02
addition to continued sectoral investigations into impacts of climate change and variabilitv. inteerated regional climate change impact studies be conducted in three key areas: the Great Lakes region, the Mackenzie Basin, and the Prairie Provinces (2). Such integrated studies would consider, in addition to the direct impacts of change on plant species and socioeconomic sectors, the role of intersectoral and ecosystem feedbacks and adaptation measures in altering the firstorder effects. The Mackenzie study, which focuses on Canada's largest river and surrounding basin (home to many of Canada's indigenous peoples), is now in its third year. Areas being investigated include the impacts of several climate change scenarios on water management, sustainability of native lifestyles, opportunities for economic development, buildings and infrastructure, ecosystem sustainability, and strategies for limiting greenhouse gas emissions. Within the project, some 30 specific studies a r ~ now under way, including analyse of forest and wetland response, tre line response, permafrost, fisheri basin runoff. ice in the Peace Riv fire and its impact on wildlife, agriculture, and tourism. The research makes use of a variety of resources, including remote sensing and traditional climate knowledge of indigenous people, and has already generated some 15 reports (34). While not as advanced in development, the other two regional studies already have a large volume
How Global Warming May Affect Canada If a doubling of atmospheric C02 concentrations (or equivalent) causes global warming a s projected by equilibrium climate models, then: * Average temperatures are likely to rise by 4-10 "C across most of Canada, with the largest increases in interior regions and in winter (14). * Interior regions of the country, including the very productive agricultural regions, appear likely to become drier, with southern river systems experiencing decreases in runoffof 25-50%. Severe drouahts can be exoected to become more frequent in these regions, and water quality is likely to'deteriorate significantly (17-21). * In those areas not affected by increased drought, an agricultural industry appropriately adapted to the changes is likely to benefit substantially from the warmer growing conditions and higher carbon dioxide concentrations. However, increased problems with pests and diseases is a concern, and p w r northern soils will limit potential for northward expansion of agricukure (22,
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Southern and dry zones of forest ecosystems are unlikely to adapt quickly enough to proiected changes. and are likely to suffer increasina - damaae - from pest< diseases, and fire (24, 25). * Warmer winters will greatly reduce space heating requirements and are likely to reduce snow removai and road maintenance-budgets. However, winter recreational industries that depend on snow cover and lake ice could become untenable in the most densely populated regions of the country. Summer cooling costs are likely to rise (2% 27). Transportation in ice-covered waters will become easier and less costly. Land transportation and pipeline systems over permafrost regions and in areas dependent on frozen winter roads will experience increased land instability and costly maintenance, and may have to be abandoned in some regions (28-31). * Both freshwater and ocean fisheries will need to cope with changing fish
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of research results from past studies as a starting basis. An advisory board has been established to guide the development of the Great Lakes study, with the recommendation that the integrated study be focused on water management, ecosystem health, land use and management, and human health (35).The Prairie regional study is still in the early
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development stage, although work has started on a comprehensive history of drought frequency, dust storms, and related soil drifting. Future directions The improving scientific understanding of the climate system and of the sensitivity of ecosystems and society to change and variability
will, in time, give rise to new and important applications of climate information. For example, reliable seasonal and annual forecasts of climate conditions and related impacts are a realistic possibility. In the future, advanced regional models coupled to improved GCMs are also likely to provide more reliable advance warnings of anomalous climate extremes a n d variations, whether as a consequence of slowly developing global warming or as a result of events such as El Nifio or major volcanic eruptions. However, one of the most pressing demands for better understanding of the climate system currently comes from the policy-making community seeking appropriate response to the risks of future global warming. Policy makers have recognized that, although the consequences of potential global warming are as yet poorly understood, the threat is real. Canadian policy makers are now developing a national action program on climate change involving three distinct yet interactive components. The first will, as a precautionary measure, seek to stabilize the anthropogenic emissions of greenhouse gases at 1990 levels by the year 2000 and explore options for further reductions. The second component will promote measures within Canada to better adapt to current and future climate conditions, thus reducing the negative consequences a n d maximizing new opportunities presented by global warming through anticipatory actions. The third component recognizes that improved scientific understanding is a critical aspect of appropriate future decisions relating to the other two components, and will seek to strengthen the Canadian scientific effort pertinent to many of the key policy questions. To ensure that it fully addresses t h e concerns of a l l Canadians, the national action program is being developed through a multistakeholder consultation process involving various levels of governments, academia, industry, environmental groups, and the general public. A final draft of the program, now being developed by a representative task group, will undergo public debate through regional workshops in the fall of 1994 and will be ready for government approval by March 1995. It promises to provide Canada with tough but fascinating challenges during the decade to come.
Downsvinw. ON. 1994.
Climntc Chonyc Di2,;st:Reports K C D 87-2 through ?CD 94-2: E&ronment Canada: Downsview, ON, 1987-1994. (17) Wall. G . : Sanderson. M.. Eds.: Procrpdings. Symposirim on Climnte Change: Implicofions for Wnferand Ecologicnl Resources; llniversity o f
(16)
L Henry H e n g e v e l d is Environment Cana d a ' s s c i e n c e a d v i s o r on c l i m a t e change. During the post 12 years in this position. he hos puhlished numerous documents on the science of glohol warming for tise hy policv makers and the public. and he regularly briefs senior decision makers within the Canadian government on new related scientific developments. He hos frequently poriicipated as a member of Canadian delegations to international meetings on scientific assessment of glohol worming and related negotiations of a climate change convention. He received n B.S. degree in physics and an M.S. degree in meteorol0g.v from the University of Toronto.
Waterloo: Waterloo. ON, 1990: Occasional Paper No. 11. (18) Wall. G.. Ed.: Proceedings. Symposium on the l m p o c f s of Climnle Chonge and Vnriobility on the Great Plnins; Calgary. Alherta: University of Waterloo: Waterloo. ON. 1990: Omssional Paper No. 12. (19) "Adaptation to Climate Change and Variability in Canadian Water Resnorces": E n v i r o n m e n t C a n a d a : Downsview. ON, 1993; CCD 93-02. (20) Cohen. S.J. Clim. Chongr 1991. I S . 291-317. (21) Williams. G.D.V. et al. In The Impncts of Climatic Voriolions on Agriculture. Vol. 1: Perry. M. ot al.. Eds.: Reidd: Dordrecht. The Netherlands. 1987. (22) Smit. R.; Rrklacich. M. Conndion Geographer 1992.36,75-8. (23) Arthur. L. M. Proirie Forum 1992. 17, 97-109. (24) Wall. G..Ed. Proceedings. Symposium on Implications of Climnlc
References Phillips, D. "The Climates of Canada": Supply and Services Canada: Ottawa. ON, 1990: EN 5fi-l/3990E. "The Canadian Climate Program: Canadian Climate Program Board": Environment Canada: Downsview, ON, 1993. "Oceans. C a r b o n a n d C l i m a t e Change: An Introduction to Joint Global Ocean Flux Study (IGOFS)"; Scientific Committee a n Oceanic Res e a r c h : I n t e r n a t i o n a l C o u n c i l of Scientific Unions: Kiel. Germany. 1990. Glooschenko. W. A. et al. 1. Geophys. Res. 1994. 99.1423-28. Rubier. I. L.: Moore. T. R.: Roolet. N. T. Ecology 1993. 74.2240-54. Moore. T.R.: Roulet. N. T. Geophys. R ~ S Lett. . 1993.~0.587-90. Hall. F. G. el al. IEEE Geoscience ond
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Chonge for Pocific Northwesl Foresl M o n n g m m l ; Seattle. Washington; University of Waterloo: Waterloo. ON, 1990; Occasional Paper No. 15. (251 Rizzo, R.: Wiken. E. Clim. Change 1992.21.37(26) "Implications of Climate Change for Down Hill Skiing in Quebec": Environment Canada: Downsview. ON, 1988: CCD 88-03, (27) "Implications of Climatc Change for Tourism and Recreation in Ontario"; Environment Canada. Downsview. ON, 1988: CCD 88-05. (28) "Impacts of Global Climate Warming for Canadian East Coast Sea-Ice and Iceberg Regimes Over the Next 50100 Years": Environment Canada: Downsview. ON, 1993; CCD 93-03. (29) Wall. G.. Ed.: Proceedings. Symposium on Impacts of Climate Change on Resource Monogemen1 in the North: Whitehorse. NWT: University of Waterloo: Waterloo. ON, 1992; Occasional Paoer No. 18. (30) Woo, M. K.: Lewkowicz. A. G.: Rouse, W. R. Phvs. Geogr. 1992. 13, 287-317. (31) Lonergan. S . ; DiFrancesca. R.: Woo, M. K. Clim.Change 1993.24.331-51. ( 3 2 ) "Socio-Economic Assessment of the Physical a n d Ecological Impacts of Climate Change on the Marine Environment of t h e Atlantic Region of Canada-Phase 1": Environment Canada: Downsview. ON. 1988: CCD 8807. (33) "Implications of Climate Change for Small Coastal Communities in Atlantic Canada"; Environment Canada: Downsview. ON, 1990: CCD 90.01. (34) "MRIS: M a c k e n z i e Basin Impact Study, Interim Report 111"; Environment Canada: Downsview. ON, 1993. (35) Mortsch. L. et al.. Eds.: Proceedings of the Great Lakes S t . Lawrence Basin Project Workshop: Quebec City. P.Q.; Environment Canada: Downsview. ON, 1993.
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