CANADA: SPECIAL REPORT

Λ I ι

THE GLOBAL WARMING CHALLENGE Understanding and Coping with Climate Change in Canada

/ anada is the world's sec­ond largest country , 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 of the west coast to the dry prai­ries in the interior and the frozen expanses of the north (2). Years of experience in coping with these varied conditions have helped Ca­nadians develop a social and eco­nomic structure that is well adapted to the realities of their climate as we know it today.

It is not surprising, therefore, that Canadians 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 up our ice-congested Arctic waters to in­creased shipping and cause the col­lapse of surface transportation sys­tems over permanent ly 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 since the mid-19th century. The resultant information, which builds understanding of the past be­havior of climate, provides an impor­tant basis both for designing our country's infrastructure and for plan­ning 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 climate-induced 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, insti tutions, and individuals. It

H E N R Y H E N G E V E L D Environment Canada

Downsview, ON, Canada M3H 5T4

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 to: • develop the ability to predict cli­mate and climate change; • assess the impact of human activ­ities on climate; • improve the use of climate infor­mation 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 na­t ional 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 Nat ional Climate Advisory Committee on Data and Applications, the Research Advi­sory Committee, and the Socio-Eco-nomic 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 sys­tem, inc lud ing the 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-

0013-936X/94/0927-519A$04.50/0 © 1994 American Chemical Society Environ. Sci. Technol., Vol. 28, No. 12, 1994 519 A

Canadian GCM projections of seasonal climate warming under a doubling of atmospheric CQ2

«UM Summer

(June, July, Aug.) (Celsius degrees)

M » Winter (Dec, Jan., Feb.)

îius degrees)

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 in 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 States-Canada 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. W A R M I N G

W O U L D NECESSITATE SIGNIFICANT

ADJUSTMENTS IN CANADIAN SOCIETY AND ITS ECONOMY.

gators suggest this carbon sink ex­ists primarily 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 the forests mature, this sink will likely disap­

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 investiga­t ions into related greenhouse sources and sinks from this sector.

Results from Canadian studies into climate system processes have made similar contributions to un­derstanding the Earth's 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 components.

General circulation models Because of the need to under­

stand how the whole, linked cli­mate system works, climate model-

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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 ocean-ographers 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 in amplifying or a t tenua t ing 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; and a more sophist icated 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 Mont­real) , a tmospher ic chemis t ry (Toronto), clouds (Toronto), paleo-climate (Ottawa), land surface pro­cesses (Saskatoon), and regional cli­mate modeling (Montreal).

Preparing for climate change Applied climatology helps Cana­

dians 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; and 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 [14, 15). 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—ecosystem-society 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 (26), 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 1991, 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 CQ2

Present day I I Tundra I I Boreal

Temperate I I Grassland I I Unclassified

addition to continued sectoral in­vestigations into impacts of climate change and variability, integrated 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 first-order 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 cl imate 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 are now under way, including analyses of forest and wetland response, tree-line response, permafrost, fisheries, basin runoff, ice in the Peace River, 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 C 0 2 concentrations (or equivalent) causes global warming as projected by equilibrium climate models, then: • Average temperatures are likely to rise by 4 - 1 0 °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 runoff of 25 -50%. Severe droughts can be expected 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 poor northern soils will limit potential for northward expansion of agriculture (22, 23). ' Southern and dry zones of forest ecosystems are unlikely to adapt quickly enough to projected changes, and are likely to suffer increasing damage from pests, diseases, and fire (24, 25). • Warmer winters will greatly reduce space heating requirements and are likely to reduce snow removal 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 (26, 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 habitats and migration or severe decline of critical fish species (32, 33).

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

development stage, although work has started on a comprehensive his­tory of drought frequency, dust storms, and related soil drifting.

Future directions The improving scientific under­

standing of the climate system and of the sensitivity of ecosystems and society to change and variability

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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 and var ia t ions , whether as a consequence of slowly developing global warming or as a result of events such as El Nino 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 and 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 the concerns of all 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.

fes/S Henry Hengeveld is Environment Can­ada's science advisor on climate change. During the past 12 years in this position, he has published numerous documents on the science of global warming for use by policy makers and the public, and he regularly briefs senior decision makers within the Canadian government on new related scientific developments. He has frequently partic­ipated as a member of Canadian delega­tions to international meetings on scien­tific assessment of global warming and related negotiations of a climate change convention. He received a B.S. degree in physics and an M.S. degree in meteorol­ogy from the University of Toronto.

R e f e r e n c e s

(1) Phillips, D. "The Climates of Cana­da"; Supply and Services Canada: Ot­tawa, ON, 1990; EN 56-1/1990Έ.

(2) "The Canadian Climate Program: Ca­nadian Climate Program Board"; En­vironment Canada: Downsview, ON, 1993.

(3) " O c e a n s , Carbon and C l ima te Change: An Introduction to Joint Glo­bal Ocean Flux Study (JGOFS)"; Sci­entific Committee on Oceanic Re­sea rch ; I n t e rna t i ona l Counc i l of Scientific Unions: Kiel. Germany, 1990.

(4) Glooschenko, W. A. et al. /. Geophys. Res. 1994, 99, 1423-28.

(5) Bubier, J. L.; Moore. T. R.; Roulet, Ν. Τ. Ecology 1993, 74, 2240-54.

(6) Moore, T. R.; Roulet, Ν. Τ. Geophys. Res. Lett. 1993, 20, 587-90.

(7) Hall, F. G. et al. IEEE Geoscience and Remote Sensing Society Newsletter 1993. 86, 9-17.

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(9) Barker, H. W.; Van Zyl, B. /. Clim. 1993, 6, 858-61.

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(13) "Modelling the Global Climate Sys­tem"; Environment Canada: Downs­view, ON, 1994; CCD 94-01.

(14) "Climate Change and Canadian Im­pacts: The Scientific Perspective"; Canadian Climate Program Board, En­vironment Canada: Downsview, ON, 1991; CCD 91-01.

(15) "Climate Change and Canadian Im­pacts: 1993 Update on Scientific Per­spect ives"; Canadian Climate Pro­gram Board, Environment Canada:

Downsview, ON, 1994. (16) Climate Change Digest; Reports #CCD

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(17) Wall, G.; Sanderson, M., Eds.; Pro­ceedings, Symposium on Climate Change: Implications for Water and Ecological Resources; University of Waterloo: Waterloo, ON, 1990; Occa­sional Paper No. 11.

(18) Wall. G., Ed.; Proceedings, Sympo­sium on the Impacts of Climate Change and Variability on the Great Plains; Calgary, Alberta: University of Waterloo: Waterloo, ON, 1990; Occa­sional Paper No. 12.

(19) "Adaptation to Climate Change and Variability in Canadian Water Re­s o u r c e s " ; E n v i r o n m e n t Canada : Downsview, ON, 1993; CCD 93-02.

(20) Cohen, S. J. Clim. Change 1991, 19, 291-317.

(21) Williams, G.D.V. et al. In The Impacts of Climatic Variations on Agriculture, Vol. 1; Perry, M. et al., Eds.; Reidel: Dordrecht, The Netherlands, 1987.

(22) Smit, B.; Brklacich, M. Canadian Ge­ographer 1992, 36, 75-8.

(23) Arthur, L. M. Prairie Forum 1992, 17, 97-109.

(24) Wall, G., Ed. Proceedings, Sympo­sium on Implications of Climate Change for Pacific Northwest Forest Managment; Seatt le, Washington; University of Waterloo: Waterloo, ON, 1990; Occasional Paper No. 15.

(25) Rizzo, B.; Wiken, E. Clim. Change 1992, 21, 37-55.

(26) "Implications of Climate Change for Down Hill Skiing in Quebec"; Envi­ronment Canada: Downsview, ON, 1988; CCD 88-03.

(27) "Implications of Climate 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 50— 100 Years"; Environment Canada: Downsview, ON, 1993; CCD 93-03.

(29) Wall, G., Ed.; Proceedings, Sympo­sium on Impacts of Climate Change on Resource Management in the North; Whitehorse, NWT; University of Waterloo: Waterloo, ON, 1992; Oc­casional Paper No. 16.

(30) Woo, M. K.; Lewkowicz, A. G.; Rouse, W. R. Phys. Geogr. 1992, 13, 287-317.

(31) Lonergan, S.; DiFrancesco, R.; Woo, M. K. Clim. Change 1993, 24, 331-51.

(32) "Socio-Economic Assessment of the Physical and Ecological Impacts of Climate Change on the Marine Envi­ronment of the Atlantic Region of Canada—Phase 1"; Environment Can­ada: Downsview, ON, 1988; CCD 88-07.

(33) "Implications of Climate Change for Small Coastal Communities in Atlan­tic Canada"; Environment Canada: Downsview, ON, 1990; CCD 90-01.

(34) "MBIS: Mackenz ie Basin Impact Study, Interim Report #1" ; Environ­ment Canada: Downsview, ON, 1993.

(35) Mortsch, L. et al., Eds.; Proceedings of the Great Lakes St. Lawrence Basin Project Workshop; Quebec City, P.Q.; Environment Canada: Downsview, ON, 1993.

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