Canadian Institute for Climate Studies        Canada Impact

Improved Decisions through Climate Research, Consulting and Interpretation

IMPLICATIONS FOR CANADA


OF RECENT IPCC ASSESSMENT REPORTS


Prepared by:


Canadian Climate Program Board

and

Canadian Global Change Program Board



The following document that describes the impacts of climate change on Canada and some of the actions that could be taken to reduce emissions of Greenhouse gases can either be read sequentially or by reference to the specific sections contained within the Index.




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1. INTRODUCTION

 IPCC assessments represent very broad international consensus

The Intergovernmental Panel on Climate Change (IPCC) was established in 1988, by the World Meteorological Organization (WMO) and the United Nations Environment Program (UNEP), at the request of governments. Its function is to assess, from published, peer-reviewed, world-wide literature, the present state of knowledge of climate change, especially as influenced by the anthropogenic factors of greenhouse gases and aerosols in the atmosphere. Its First Assessment Report was issued in 1990. An update was prepared in 1992 for the negotiators of the Framework Convention on Climate Change (FCCC) and, in addition, a special report "Climate Change 1994" was later completed by IPCC to assist the first meeting of the Conference of Parties (Berlin, March- April 1995). It focussed on "Radiative Forcing of Climate Change" and on "Evaluation of the IPCC IS92 Emission Scenarios".

The Second Assessment Report will provide an up-to-date report of the current scientific and economic understanding of climate change.

IPCC's Second Assessment Report is currently (November, 1995) being finalized, with all parts having undergone peer reviews and government reviews. For the first time the draft reports contain an assessment of economics literature and that of some of the other social sciences. Canada has provided the Co-Chair and Technical Support Unit for this part of the assessment and several lead authors for all Working Groups. The reports will be completed and approved by IPCC members by the end of 1995 but their main thrust and assessments are reasonably well-established.

The full Second Assessment Report has four sections:



This report is intended to assist Canadian policy makers as they work to implement commitments under the Framework Convention on Climate Change.

This report, by the Canadian Climate Program Board and Canadian Global Change Program Board, is intended to assist Canadian policy makers by extracting the key assessment findings, of particular relevance to Canada, from the 1994 Report and the 1995 Draft Report.

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2. CLIMATE CHANGE 1994

2.1 Radiative Forcing

The main conclusion was that there have been significant additions to our knowledge but these "do not substantially change the essential results concerning radiative forcing of climate" contained in the 1990 and 1992 assessments. (The earlier reports examined not only the effect which radiative gases have in altering the energy balance of the Earth, but also reviewed a wide range of information on how climate has behaved in the past and how it might change in the future as a result of human influence).

While the fundamental conclusions of the latest IPCC reports are consistent with earlier findings, there are a number of refinements in knowledge.

However, several recent refinements in understanding are important. One is that the direct negative radiative forcing (cooling) due to aerosols (primarily aerosols from fossil fuel burning) is regionally very significant. This offsets or "masks" to some extent the greenhouse gas warming. It is regionally most significant in Eastern North America, Europe and S.E. Asia where acid rain is a serious problem due to sulphate emissions. (The lack of significant observed warming over the past few decades in extreme eastern Canada, compared to warming of central and western Canada may be partly due to this effect). Further efforts to curb sulphate emissions are likely to unmask greenhouse warming and accelerate warming in regions where sulphate aerosols have been historically high, including central and eastern Canada. Globally, the direct effect of aerosols may offset as much as 40% of the direct greenhouse gas effect due to carbon dioxide, methane, nitrous oxides and halocarbons (diagram next page). However, aerosols have very short lifetimes in the atmosphere (days to weeks) compared to that for the greenhouse gases (a few, to many decades). There may also be substantial indirect effects of aerosols through induced cloudiness. While still difficult to quantify, these are probably negative.

On the other hand, the refinements reported in 1994 indicate that increases in tropospheric (low level) ozone in urban and regional smog, especially in industrialized regions have had a positive (warming) radiative effect, adding about 20% of the direct greenhouse gas effects globally, and more regionally. Low-level ozone is also short-lived in the atmosphere.

The assessment also presents the results of Carbon-cycle modelling to determine how vigorous an action is needed to achieve stabilization of atmospheric concentrations of CO2 in the area of 350 ppmv (parts per million by volume - about present levels) to 750 ppmv (a little more than 2 times present or 2 2/3 pre-industrial levels). The assessment concludes that stabilization of concentrations within this range "could be attained only with global anthropogenic emissions that drop substantially below 1990 levels"

The temporary 2-year global cooling in 1992 and 1993 of about 0.40 C, induced by the massive injection of aerosols into the stratosphere by the Mt. Pinatubo eruption, is approximately the magnitude predicted by General Circulation Models (GCMs) of the climate system. This lends additional confidence to model projections of changes in global climate due to changes in radiative forcing.

2.2 Evaluation of Emission Scenarios

Future carbon dioxide emission scenarios suggest that, without policy intervention, cumulative emissions in the next century will be far greater than those to date.

The "IPCC IS 92 (a) through (f)" emission scenarios were developed as "standardized" inputs to GCMs, as a basis for determining the likely consequences of inaction to limit greenhouse gas emissions. The six scenarios are projections, to the year 2100, of future anthropogenic emissions of the various greenhouse gases and aerosols, under a range of estimates of future population growth rates, economic development, energy mixes and so on. The lowest projections, IS 92c and d, assume that global population grows from about 5.8 billion at present, to only 6.4 billion by 2100 - an increasingly unlikely outcome. The mid-range scenarios (IS 92a and b) assume populations of 11.3 billion by 2100 (World Bank median projections) and medium economic growth projections (2.3% per year globally). They are used most frequently as "business as usual" projections. The high-range projections (IS 92f and e) assume 17.6 billion people by 2100 (IS92 f) or a high rate (3%) of global economic growth (IS 92e).

The 1994 evaluation compared these scenarios with 41 sets of other published scenarios, both from the point of view of their emission outcomes and their input assumptions. It was found that the IS92 scenarios fall well within the range of published non-policy international scenarios, although IS92 c, the lowest, "has emission levels and some input assumptions more characteristic of an intervention than a non-intervention scenario". Nevertheless, it was recommended that the full range of IS92 scenarios be used in climate modelling to assess the likely consequences of no intervention.

Other key assessment findings were:



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3. SECOND ASSESSMENT REPORT - NATURAL SCIENCE

3.1 Background

The second scientific assessment of climate change is a comprehensive review of our understanding of climate change.

Approximately 400 scientists (including 21 Canadians), from a broad range of scientific disciplines and international research institutions, were contributing authors to the writing of this assessment report. In addition, the assessment was submitted for peer review to approximately 700 scientific experts in more than 150 countries.

The fundamental conclusions of the second full assessment are consistent with those presented in the first assessment, which was published in 1990, and the subsequent update presented in 1992. The thousands of new scientific studies upon which the new assessment is based have provided a marked improvement in the overall understanding of the climate system and how it changes in response to a number of forcing factors. This enhanced understanding has increased the confidence in many of the provisional conclusions reported in the earlier reviews. Of particular significance are:

Global temperature increases over the past century "are unlikely to be entirely due to natural variability - a pattern of climatic response to human activities is identifiable in the climatological record"

3.2 Trends in Greenhouse Gas Concentrations

Concentrations of most greenhouse gases continue to increase.

Ice core studies indicate that atmospheric concentrations of carbon dioxide, which fluctuated around 280 parts per million by volume (ppmv) during the last 18,000 years, began to increase concurrently with industrialization that began approximately 200 years ago. By 1994, atmospheric concentrations of carbon dioxide had reached 358 ppmv, an increase of almost 30% over pre-industrial levels. The rate of growth, which slowed significantly in 1992/93, returned close to the average rate observed in the previous decade (about 1.6 ppmv per year) during 1994. These observations support other evidence that indicates the recent slowdown in growth was due to a large but transitory perturbation in the global carbon cycle, caused by a temporary and natural increase in uptake of atmospheric carbon dioxide by land ecosystems and ocean waters.

The above growth rates suggest that slightly less than one-half of human-induced emissions of carbon dioxide, both from the combustion of fossil fuel and changing patterns of land use practices, remain in the atmosphere. The remainder is believed to be taken up by natural sinks, primarily by oceans and, to a lesser extent, by enhanced vegetation growth on land. The latter is attributed to the combined effects of new forest growth, the direct fertilization effects of enhanced concentrations of carbon dioxide on most plants, and possible enhanced growth caused by warming climates and other related factors.

Global land ecosystems will likely continue to be a significant sink for CO2, but this sink is expected to become smaller within decades as their response to warmer climates and CO2 fertilization effects stabilizes.

Where forests die due to climate stress, the carbon in the forest is rapidly released through fire and decay. Canadian studies suggest that our forests have, in past decades, been a significant sink for carbon dioxide. However, a significant increase in the hectares of Canadian forests burned by wildfire over the most recent decade has largely offset this sink. Any continued increase in such fire losses as a result of climate change is likely to turn Canadian forests into a significant source of carbon dioxide over the coming decades.

By the year 2100, carbon dioxide concentrations are expected to be two-to-three times those of the pre-industrial period.

Analyses of a range of future carbon dioxide emission scenarios suggest that a doubling of pre- industrial concentrations of carbon dioxide in the atmosphere by the year 2100 is highly likely, and a tripling a distinct possibility. In order to stabilize concentrations at 650 ppmv (still more than a doubling of pre-industrial levels) a reduction in global carbon dioxide emissions to about 50% of current emissions would eventually be required.

Concentrations of methane and nitrous oxide continue to rise slowly.

Concentrations of methane (the second most significant greenhouse gas), following a period of very little growth in 1992/93, also resumed a growth rate in 1994 close to that of the preceding decade. These rates, however, are significantly less than those observed in the late 1970s, suggesting a continuing long-term reduction in growth rate. Causes of this reduction are as yet uncertain, although a decrease in emissions from fossil fuel production activities in the Northern Hemisphere may be a factor. A 5% reduction in current global emissions is estimated to be sufficient to stabilize methane concentrations, since the life-time of this gas in the atmosphere is relatively short.

Nitrous oxide concentrations also continue to rise at about 0.25% per year. Because of its long life- time in the atmosphere, a stabilization at current levels would allow concentrations to continue to slowly increase, reaching levels about 45% above pre-industrial levels, over the next two centuries.

Significant change has been noted in growth trends of the halon grouping of greenhouse gases. A number of greenhouse gases covered under the Montreal protocol for ozone-depleting substances show remarkable declines in growth rates. Concentrations of methyl chloroform, for example, have actually decreased by 8% in 1994, while CFC-11 levels have stabilized and growth rates in CFC-12 concentrations have slowed dramatically. However, concentrations of less abundant HCFCs and HFCs continue to grow rapidly (at rates of up to 50% or more per year), while concentrations of the extremely long-lived and potent sulphur hexafluoride (lifetime of 800 to 3200 years) are increasing at 7% per year.

3.3 Effects of Past Emissions on the Climate System

The net effect of increased concentrations of well-mixed greenhouse gases is equal to slightly more than a 50% increase in carbon dioxide alone.

The combined effects of well-mixed greenhouse gases on the net radiative flux into the lower atmosphere, including the offsetting cooling effects of related stratospheric ozone depletion, is estimated at 2.35 watts/square meter (w/m2), compared to an increase of 4.35 w/m2 for a doubling of carbon dioxide. Increases in carbon dioxide represent approximately two-thirds of this increase.

Highly variable increases in concentrations of ozone in the lower atmosphere of the Northern Hemisphere have added another 10 to 25% to the effects to-date of the well-mixed gases.

Large regional increases in concentrations of anthropogenically-generated aerosols (sulphates and smoke particles) have a significant net cooling influence on the earth's surface, both directly by reflecting sunlight and indirectly by increasing cloud reflectivity. This cooling effect can be very large over, and downwind of, heavily industrialized areas such as Eastern Canada. While the net effect of these aerosols on radiative forcing is considerably more uncertain than that for greenhouse gases, preliminary estimates suggest this effect to-date may have directly reduced net globally- averaged downward radiation by about -0.4 w/m2, and indirectly by an additional 0 to -1.5 w/m2. This cooling effect varies from region to region, unlike the warming effects of well-mixed greenhouse gases, and would respond very quickly to reductions in aerosol emissions because of the short life time of these aerosols in the atmosphere (about 1 week).

Changes in radiation from variations in intensity of sunlight reaching the earth can be significant, but, on a century time-scale, are estimated to be much smaller than those due to greenhouse gases.

3.4 Climate Model Simulations

Climate models continue to project future climate changes, by the year 2050, that would be unprecedented in the last 10,000 years.

Substantial progress has been made in model development and performance in recent years, particulary with respect to large-scale ocean and land surface processes. Current models include the most important physical processes affecting the global climate system and are now able to simulate the large-scale features of the current climate (including climate variability on seasonal and longer time scales) reasonably well. Furthermore, these models show skill in simulating the climate effects of past events such as volcanic eruptions and geological-scale changes. Hence, there is good confidence in the basic integrity of the models and their ability to provide useful information on the large-scale aspects of future climate change.

While climate models provide more realistic projections at global- or continental-scale, confidence in projected regional-scale changes remains low.

One of the most significant limitations of the ability of models to simulate rates and regional characteristics of climate change is the inadequate description of clouds, and the role of water cycle and other important processes within the atmosphere, oceans and land surfaces (particularly on small spatial scales). Another is the continuing need for corrections to atmosphere-ocean fluxes in the coupled GCMs. Despite the major improvements noted, much more work remains to be done to address these shortcomings. As a result, confidence in the regional-scale changes predicted by the models remains low.

The rate of global warming will slowly accelerate reaching a net warming of up to 4.5 degrees Celsius by the year 2100

Continued emission of sulphate aerosols, which produce acid rain, could reduce expected temperature increase by about 25%.

Models predict that the current rate of global warming of about 0.1 0C/decade will slowly accelerate in response to continued increases in greenhouse gas concentrations, reaching a net warming of 1 to 4.50C by the year 2100. If emissions of aerosols continue to increase, they could reduce this rate by about 25%, with a projected net warming by 2100 of 1 to 3.50C relative to today. On the other hand, decreased emissions of aerosols from reductions in other environmental hazards such as acid rain, would remove their masking of the full effect of greenhouse gases quite rapidly.

The predicted rise in temperatures will not be steady, since such human-induced changes will be superimposed on a naturally- varying climate system.

Annual temperatures over north-central Canada could increase by 5 degrees C., and as much as 8 degrees C. in winter, by the middle of the next century.

Interiors of continents are expected to warm faster, with maximum warming in high-latitude winters. Various scenarios predict, for example, that average temperatures over north-central Canada could be warmer by up to 50C by mid-century, and as much as 80C warmer in winter. Meanwhile, adjacent oceans are projected to only warm by a maximum of 30C. Diurnal temperature range decreases in most seasons and regions.

The global hydrological cycle will intensify, with increased global mean precipitation and greater soil moisture in high northern latitudes in winter. Most models also predict lower summer moisture in continental regions of mid-northern latitudes. Some predict increased frequency of extreme rainfall events, but also longer and more intense droughts.

Sea levels over the next century may rise as little as 15 cm and as much as 95 cm (with a most likely value of 50 cm.). The rate of change depends on the rate of global warming, the extent of masking of such warming by aerosols, and the response of global ice caps. Disintegration of the West Antarctic ice cap, which would cause a much larger rise, is not likely but the risk cannot be excluded. Much of the rise over the next century will be a delayed response to warming caused by past increases in greenhouse gases, while present and future emissions will cause continued sea level rise centuries into the future, long after such emissions occur.

3.5 Climate Observations

Global temperatures have increased by 0.3 to 0.6 degrees C. over the past century, with most of that rise having come in the past 40 years.

Central and Northwestern Canada has warmed by up to 0.5 degrees C. in the past 30 years, while east of the Labrador coast, cooling of 0.4 degrees C. has been observed. This is consistent with climate model projections with increased greenhouse gases.

Global temperatures have increased by 0.3 to 0.60C over the last century, and 0.2 to 0.30C during the past 40 years. More of this increase has been due to warmer nights than warmer days. Summer temperatures in the Northern Hemisphere appear now to be the warmest since at least 1400AD. The regional patterns of recent warming show considerable variability, with the largest warming occurring over continents between 400N and 700N, while some other areas have experienced cooling. Much of central and north-west Canada, for example, has warmed by more than 0.50C during the last 30 years, while temperatures over waters in the north Atlantic have actually cooled by more than 0.40C during the same period. Both the observed rate and geographical patterns of global temperature change are broadly consistent with model projections of the combined climate effects of past increases in greenhouse gas and aerosol concentrations.

The frequencies and intensities of El Nino events in the equatorial Pacific Ocean, which affect weather patterns around the world, began a new behavioral regime around 1976/77. This new regime, which is highly unusual in at least the last 120 years of climate history, appears to be an important factor on many of the recently-observed changes in climate patterns around the world.

Arctic sea ice extent has been below average since 1990, while Northern Hemisphere snow cover has consistently been below average since 1988.

Cloudiness appears to have increased over land and sea, and precipitation has increased over land in high latitudes, particularly in winter. Over Canada, cloud cover has increased by about 1% over the past 40 years, with greatest increases (3%) during the spring season and very little change in summer.

Sea levels have been very stable for most of the past 1000 years, but have increased by 1 to 2.5 cm/decade during the past century. There is no evidence of acceleration in the rate of sea level increase during the century.

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4. SECOND ASSESSMENT REPORT - IMPACTS, ADAPTATIONS AND MITIGATION OPTIONS

4.1 Background

The IPCC Working Group II Draft Second Assessment Report provides a wealth of detail on potential impacts and adaptation and mitigation responses all over the world. The Report contains 28 chapters, numbers nearly 800 pages and has a list of some 550 lead and supporting authors (dozens of whom are Canadians). While it provides an excellent global inventory of potential impacts, it does not, however, provide a direct national assessment of impacts on Canada.

The first and foremost implication of the IPCC work is, therefore, to suggest an urgent need for a national impacts and adaptation assessment for Canada.

Climate change will impact directly upon the Canadian environment and society, and also indirectly as a result of impacts elsewhere in the world.

The impacts of climate change on Canada are of two kinds. The direct impacts upon the Canadian environment and society, and the indirect effects that will be felt by Canada as a result of impacts elsewhere in the world. One important reason for this is that Canada and Canadians have a greater capacity to adapt than now exists in most other regions of the world.

A number of detailed impact studies of sectors and regions have been made in Canada, but significant gaps in research exist and the existing studies have not been synthesized into an integrated picture, nor have concerted attempts been made to evaluate impacts in monetary forms.

4.2 Vulnerabilities, Selected Impacts

The Working Group II Report shows that human-induced climate change will be a major additional stress in a world where the environment is already being seriously damaged and depleted by increasing resource demands and non sustainable management practices:

4.2.1 Human Health

There is a serious threat to human health.

There is a serious threat to human health. In high latitude (Canada) and developed countries there is a danger of increased exposure to heat stress in very hot weather events, and more frequent weather hazards (e.g. droughts, floods, wildfires and severe storms) with resulting injuries, deaths and damage to infrastructure that supports public health.

Globally, the most alarming threat is an increase in transmission of vector-borne infectious diseases.

From a global perspective the most alarming threat is an increase in transmission of vector-borne infectious diseases as the vector organisms spread and extend their range. Major increases are possible in the incidence of malaria, dengue and yellow-fever, schistosomiasis and river-blindness, events which are likely to compound conditions of poor environmental health conditions in many countries. The problem could be further exacerbated by regional food shortages and consequent under-nutrition. In a smaller world with rapid air travel and mass tourism and migration, a deterioration in health levels in developing countries would also pose a threat to Canada.

4.2.2 Water Systems

Major impacts are expected on water systems.

Major impacts are expected in regional water supplies and demands, resulting in chronic shortages where water supply is already limited.

The quality and quantity of fresh water for domestic water supply, agriculture, hydroelectricity, thermal power generation, municipal and industrial water supply, water pollution abatement and inland navigation is already insufficient in many regions of the world, especially the arid and semi- arid areas. Even in North America, periodic water shortages in the U.S.A. have resulted in calls for increased diversions southward, from the Great Lakes. With climate change these stresses will extend to other areas, resulting in hardship, threats to health and, most serious to contemplate, strong competition for control of sources among competing users both within and between countries. Such competition is often a contributing cause of armed conflict.

Canada has a well-recognized interest in international law and order, and plays a major peace- keeping role. The necessity for such actions on a much larger scale is a probable outcome of the impact of global warming on water systems.

4.2.3 Natural Ecological Systems

Aquatic and terrestrial ecosystems provide food, transportation, timber, flood control, water supplies, recreation and biodiversity, all of which are sensitive to climate change.

Climate change will add a major additional stress on natural ecological systems.

Natural ecological systems are now under heavy stress from human resource demands. Wildlife and fish stocks are endangered, with serious economic and socio-cultural consequences. Climate change will add a major additional stress factor.

The boundaries of ecosystem regions are likely to move a lot faster than most species can migrate, resulting in significant species loss and decline in biodiversity. Such dangers will have a direct impact on Canada. The most outstanding concern is for the future of the great boreal forest which could be reduced to a mere remnant of the present size.

4.2.4 Forests

Forests, especially Canada's Boreal forest, are particularly vulnerable.

Between 14 and 65% of the world's forested areas would undergo major changes in vegetation type, with implications for management and commodities. Large forested areas which now provide a large and varied supply of forest products are under threat from climate change because, like natural ecosystems, they cannot move (or be moved) rapidly enough to adapt to the poleward shift of temperate bands. A poleward shift in the range of 160-640 km. over the next 100 years is expected, while the historical migration rates for many species are in the range of 4-200 km per century.

Boreal forests (including Canada's) are particularly vulnerable: in addition to direct effects on growth, indirect effects such as increased forest fire frequency and pest outbreaks are likely to decrease average forest age, biomass and carbon storage.

4.2.5 Coastal ecosystems and coastal zones

Salt-water marshes, mangroves, wetlands, coral reefs and atolls together provide a wide range of goods and services and play a vital role as habitats and nurseries (breeding grounds, and safe places for small fry).

Sea level rise will impact on coastal infrastructure and ecosystems.

Projected sea-level rise threatens to destroy many of these sensitive natural areas and terminate their key role in ecosystems. Sea-level rise will have a number of negative impacts on tourism, ports, harbours, human settlements, agriculture, the insurance industry and cultural systems and values. There is serious risk of permanent loss of land - some of which is densely-populated in countries where available land for alternate development is in short-supply or non-existent. High-cost options to protect coastal areas from sea level rise do exist, but they are likely to be prohibitively expensive for all except the most committed governments. The largest impacts on Canada are likely to be experienced in the lower Fraser delta lands in B.C. and in a few coastal cities in eastern Canada including Charlottetown, P.E.I.

4.2.6 Agriculture

There may be significant new opportunities for Canadian agriculture in a warmer world, provided sufficient precipitation is available and adaptation measures taken. Agriculture in poorer countries could be adversely affected.

In aggregate, it seems that the gains and losses will average out, such that there will not be a major threat to world food production, assuming suitable and cost-effective adaptation measures can be implemented. On the other hand, the lesser ability to adapt agriculture to changed climate in some regions, especially the poorer regions of the planet, will have a potentially large regional impact, including security of food. There may be significant new opportunities for Canadian agriculture in a warmer world, provided sufficient precipitation occurs in food-producing areas. Other regions are likely to be adversely affected. In Canada, northward expansion of cultivation could also lead to conflict with existing land use and the stakeholders in forestry, wildlife habitat and hunting. This could pose an additional threat to native lifestyles.

4.3 Adaptation

Adaptation will be important to limit losses or to take advantage of changing climatic conditions.

Adaptation will be important to limit losses or take advantage of changing climatic conditions. While considerable adaptation potential does exist in Canada, no systematic efforts have yet been made to estimate the costs of adaptation.

It seems that agriculture, forests, water resources, human settlements and human health can all be protected from the worst impacts of climate change by a strategy of adaptation, but at high cost.

There may be few or no possibilities for adaptation in some sectors or geographic regions; even where adaptation is possible, there may be a high cost. In the case of natural ecosystems and the ice world (cryosphere) and high mountains, there are few or no possibilities for adaptation and major losses can be expected. In cold mountain climates and in the Canadian Arctic major losses of habitat and existing species of wildlife can be expected. Over the longer term these are likely to be replaced by other species to the extent that biodiversity could be increased.

A major conclusion of IPCC Working Group II is that the impacts of climate change will vary considerably from region to region. Impacts will be less where socio-economic systems and institutional response capacity are strong. Consequently, the poor and less-developed regions are most at risk.

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5. SECOND ASSESSMENT REPORT - ECONOMIC AND SOCIAL SCIENCES

5.1 Purpose and Nature of the Working Group III Report

WG III of IPCC was tasked with an evaluation of emission scenarios and an assessment of the socio- economic literature.

IPCC Working Group III was set up to examine "cross-cutting economic and other issues related to climate change". The Work Plan developed at the first plenary session in Montreal in May, 1993, and approved at the IPCC Plenary in Geneva in June, 1993, consisted of two parts:

The first part of the Work Plan was completed in early 1994 and included in the 1994 Special Report. These findings are discussed above in section 2.2. This section discusses the findings of the second part of the Work Plan, which is being published as a separate report in late 1995.

Following the 1993 IPCC Plenary, 68 of the worlds leading economists, social scientists and other experts (from 27 countries) contributed, as lead authors, to the 11 Chapters of the basic WG III technical report, addressing the following issues:

The draft chapters, and a "Summary for Policy Makers" prepared from them, were revised twice: first through an extensive peer review by some 500 experts; and then by governments (country review). The Summary for Policy Makers was further revised in the course of two IPCC WG III Plenary sessions, involving more than 70 governments and 8 Non-Government Organizations (NGOS), held in Geneva (25-28 July, 1995) and Montreal (10-13 October, 1995).

5.2 The Canadian Context

Canada is one of the world's highest emitters of GHGs, on both a per capita and per dollar of GDP basis.

The implications of the Working Group III report for Canada are strongly influenced by the particular circumstances of Canada with respect to climate change. Canada is one of the world's highest emitters of GHGs on both a per capita and per dollar of GDP basis. Unlike most other industrialized countries, Canada is also a net exporter of energy with very large areas of forested land and one of the world's biggest forestry industries which account, directly and indirectly, for a large proportion of GDP. The energy intensity of Canadian society is high by industrialized country standards even allowing for climate, geography, and industrial structure, thus providing a large relative potential for energy efficiency gains.

Canada is also perceived as a world leader in environmental issues in general, and climate change issues in particular, being a champion and early ratifier of the Framework Convention on Climate Change (FCCC).

5.3 Key Findings of the Working Group III Report

A number of key findings with direct policy relevance are contained in the WG III Summary for Policy Makers:

Damage estimates from a 2-30C global warming are a few percent of world GDP

5.4 Implications for Canada

5.4.1 Domestic Policy

The preceding findings lend support to the view that Canada, like other industrialized countries, should articulate and implement a comprehensive GHG mitigation strategy. Such a strategy should comprise a flexible portfolio of options which break down logically into several parts:

Such a framework provides guidance as to the general categories of response options but does not itself indicate what specific options should be chosen within each category. With regard to the basis for choosing from among the different specific policy measures that might be involved in implementing a strategy of the kind suggested here, the Working Group III Summary for Policy Makers identifies that the four following principles are consistent with the findings of the economic literature:

Principles such as these can be used to choose from among a wide range of specific policy measures. A partial list of possible policy measures includes: