1. Introduction

The United Nations organization responsible for developing consensus assessments of the scientific, technical and economic aspects of climate change is the Intergovernmental Panel on Climate Change (IPCC). In a series of reports beginning in 1990, the IPCC has documented the evolution of knowledge on this issue as reflected in the published technical literature. IPCC reports involve many hundreds of specialists from around the world as lead authors, literally thousands of expert reviewers, as well as reviews by governments. Thus, they represent a broad consensus on a complex issue. A number of Canadian specialists have been involved as lead authors and in providing leadership to IPCC Working Group 3 (WG3—economics).

An up-to-date summary for Canadian policy-makers.

This summary of the implications for Canada of IPCC Assessments is intended to assist policy-makers in Canada. It was prepared by the Canadian Climate Program Board and the Canadian Global Change Program Board of the Royal Society of Canada, and emphasizes up-dated material in the 1994 Special Report and the draft 1995 Second Assessment Report of the IPCC. The quotations from the IPCC reports are from the Summaries for Policy Makers of the three Chapters and Synthesis Report, or Technical Summaries, unless otherwise noted.

2. Are Human Activities Changing Climate?

• Increases in greenhouse gas concentrations lead to a positive radiative forcing of climate, tending to warm the surface and to produce other changes in climate.
• The atmospheric concentrations of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) have grown significantly since pre-industrial times: by about 30%, 145% and 15%, respectively. These trends can be attributed largely to human activities, mostly fossil fuel use and agriculture.
• Tropospheric aerosols (microscopic airborne particles) resulting from the combustion of fossil fuels, smelting, and biomass burning give rise to a negative radiative forcing over particular regions.

  Climate records point towards a detectable influence of human activities.

• Global mean surface temperature has increased by between about 0.3 and 0.6°C since the late l9th century;
• Recent years have been among the warmest since 1860, i.e. in the period of instrumental record.
• A trend towards higher frequency of extreme rainfall in recent decades was evident in Japan, the U.S.A., former Soviet Union and China. (WG1 Chapter 3)
• There is evidence of an emerging pattern of climate response in the observed climate record to forcings by greenhouse gases and sulphate aerosols. The evidence comes from the geographical, seasonal and vertical patterns of temperature. Taken together, these results point towards a detectable human influence on global climate.

CCPB/CGCP Comments

Observed changes have been far from uniform over Canada: much warming in west and northwest; cooling off Labrador coast.

In Canada this pattern of observed changes has taken the form of major winter and spring warming in western and northwestern parts of the country, with little change in the extreme east and a cooling off the Labrador coast. Both the overall change and geographical patterns are broadly consistent with model projections of the effects of greenhouse gases and aerosols. Nationally a statistically significant warming of 1°C between 1895 and 1992 has occurred (Environment Canada. State of Environment Report 95-1 "The State of Canada's Climate Monitoring Variability and Change", May 1995. )The temporary 2-year global cooling in 1992 and 1993 of a few tenths of a degree Celsius induced by the Mt. Pinatubo eruption, was reasonably well predicted by models (GCMs) of the climate system.

3. What Future Changes Are Likely Without Limitations of Greenhouse Gases?

Greenhouse gas concentrations will continue to increase without policy intervention.
• All the IS92 (IPCC Scenarios - 92) scenarios of future greenhouse gas and aerosol emissions, (even one which assumes very little population growth between the present and the year 2100) imply increases in greenhouse gas concentrations relative to pre-industrial levels by 2100 (e.g. CO2 increases range from 75 to 200 percent; methane [CH4] increases to between about three and six times the pre-industrial level).
• The increasing realism of simulations by coupled ocean-atmosphere climate models has increased our confidence in their use for projection of future climate change.

  Future rates of change greater than in past 10,000 years.

• From the mid-range IPCC emission scenario, IS92a, assuming the "best estimate" value of climate sensitivity and including the cooling effects of projected future increases in aerosols, models project an increase in global mean surface temperature relative to the present of 2.0°C by 2100 with a range of estimates from 1°C to 3.5°C(Note: If sulphate aerosols are controlled to reduce acid rain, as is now under way in North America and Europe, the projected mean temperature with greenhouse gases alone would be about 2.4°C with a range from 0.8°C to 4.5°C by 2100). In all cases the average rate of warming would probably be greater than any seen in the last 10,000 years. Models projectan average increase in sea level of about 50 cm by 2100 with a range of estimate from 15 to 95 cm (taking into account the aerosol effect).

  Possibly more heavy rains and longer dry periods would occur in a greenhouse gas-enhanced climate.

• Many models suggest an increase in the probability of intense precipitation with increased greenhouse gases. In some areas a number of simulations show there is also an increase in the probability of dry days and the length of dry spells (consecutive days without precipitation).

  Urgent scientific and measurement problems remain.

• Many factors currently limit our ability to model future climate change (and require further scientific efforts). In particular there are inadequacies in:
• estimates of future emissions of greenhouse gases, aerosols and aerosol precursors;
• representation of climate processes in models (especially those associated with clouds);
• observations of climate (improved systematic measurements).

CCPB/CGCP Comments

Different regions of Canada will experience either significant warming (northwest and central) or cooling (offshore Labrador).

The projected temperature changes would be far from uniform. Warming much greater than the global average would be expected in the Canadian Arctic, northwestern and central regions, with likelihood of continued cooling off the coast of Labrador. Analysis of Canadian Climate Centre model output suggests no increase in numbers of tropical cyclones (hurricanes) but an increase in tropical cyclones of high intensity. This model also projects dryer conditions in the Great Plains. Canada should increase its efforts to measure systematically climatic and oceanographic conditions over our land and sea areas, and contribute to the Global Climate Observing System.

4. Will There Be Significant Impacts? (IPCC Working Group 2)

Health impacts could be serious.

Human-induced climate change is an important stress. Climate change will have a significant impact directly upon the Canadian environment and society, and also indirectly as a result of impacts elsewhere in the world. While there will be some beneficial effects of climate change, there will be many adverse effects, some potentially irreversible.

Although quantitative estimates of the impacts of climate change on ecological and socio-economic systems are difficult due to uncertainties regarding climate change at the regional scale, as well as limited understanding of many climate impact processes and the influence of other factors, numerous studies have identified potential effects.

• Studies in selected urban populations in North America and East Asia indicate that the number of heat-related deaths would increase several-fold in response to two climate change scenarios for 2050. In large cities, this would represent several thousand extra deaths annually. Climate-related increases in malaria incidence is estimated by one model to be of the order of 50-80 million additional cases annually, relative to an assumed global background total of 500 million by 2100. These would occur primarily in tropical, subtropical, and less well protected temperate-zone populations currently at the margins of endemically infected areas. Higher temperatures, in urban environments, would enhance both the formation of secondary pollutants (e.g. ozone) and the health impact of certain air pollutants.

  Relatively rapid temperature changes and increased fire and pests could have major boreal forest impacts.

• Climate change is expected to occur rapidly relative to the speed at which forest species grow, reproduce (in boreal forests), and re-establish themselves. An average global warming of 1-4°C over the next 100 years would be equivalent to shifting isotherms poleward approximately 160-640 km or an altitude shift of 150-650 m. This compares to past tree species migration on the order of 4-200 km per century. Entire forest types may disappear, and new ecosystems may take their places.
• Increased fire frequency and pest outbreaks are likely to decrease the average age, biomass and carbon store of forests, with greatest impact at the southern boundary, where the boreal coniferous forest is likely to give way to temperate zone pioneer species or grasslands.

  Food production would not change much globally but could decline in most critical regions.

• Recent studies support evidence that, in the aggregate, climate change will produce small to moderate effects on global agricultural production. Subtropical and tropical areas home to many of the world's poorest people show negative consequences more often than temperate areas. People who depend on isolated agricultural systems in semi-arid and arid regions face the greatest risk of increased hunger due to climate change. Many of these at-risk populations live in sub-Saharan Africa; South, East, and Southeast Asia; and tropical areas of Latin America, as well as some Pacific island nations.
• Many coastal zones (especially the very productive estuaries) and small islands are particularly vulnerable to direct effects of climate change and sea-level rise. Present estimates of global sea-level rise represent a rate two to five times that experienced during the last 100 years.
• Relatively small changes in temperature and precipitation can have large, often nonlinear effects on runoff and lake levels particularly in arid and semi-arid lands. This can affect water supply, demand and hydro-power production. Even in areas where models project a precipitation increase, higher evaporation rates may lead to reduced runoff. More intense rainfall would tend to increase flooding. A 50 cm sea level rise would increase the number of people world-wide subject to coastal inundation from 46 to 92 million.

CCPB/CGCP Comments

Canadian adverse health impacts concentrated in large southern cities.

For Canada, the greatest health impacts would probably be concentrated in large, southern, urban centres due to heat stress, and more prolonged and intense smog episodes. Increased fires, as recent experience indicates, could have serious impacts on forests and forest communities.

Increase in Prairie agricultural production possible if adaptation and adequate rains occur.

Increased agricultural production on the Prairies is a possibility with higher temperatures and CO2 levels, provided adaptation measures are undertaken and adequate rainfall occurs. However, some models project more frequent and serious drought. Canadian and U.S. studies project a lowering of Great Lakes levels with adverse impacts on shipping and hydro power.

Large areas of permafrost presently over half of Canada's landmass will melt, disrupting landscapes and infrastructures (buildings, pipelines, roads). The consequence would also be the release of methane and gas hydrates locked in the permafrost, which would significantly contribute additional greenhouse gases to the atmosphere.

Indirect impacts could also be important.

Canada would be indirectly affected by increased pressure for immigration (environmental refugees) and more conflicts over scarce resources in developing regions. This could result from sea level rise, reduced agricultural production in tropics and subtropics, reduced water supplies in critical areas, and greater spread of vector-borne tropical diseases.

5. What Can Be Done and What Would It Cost?

• Estimates of aggregate net damages from a 2-3°C global warming tend to be a few percent of world GDP, with, in general, considerably higher estimates of damages to developing countries, especially small island states, as a share of their GDP. However, these damage estimates are difficult, uncertain and controversial;

  Estimates of net global climate change damages, much larger in developing countries, argue for going beyond "no regrets".

• The risk of aggregate net damage due to climate change, consideration of risk aversion and the precautionary principle, provide rationales for greenhouse gas mitigation actions beyond "no regrets".

  Significant cost-effective energy efficiency measures are possible.

• Energy efficiency gains of perhaps 10-30 percent of current energy use can be realized over the next two to three decades, with net economic benefits to zero net cost (an example of "no regrets" measures).
• The range of estimates from macro-economic models of costs in OECD countries of stabilizing emissions at 1990 levels range from minus 0.5 percent of GDP (an economic benefit) to plus 2 percent of GDP. Other models which emphasize technological options ("bottom-up" models) indicate that costs of reducing emissions by 20 percent in developed countries over the next two to three decades are negligible or economically beneficial.

  Environmental and economic "double dividends" can help offset mitigation costs.

• There are potentially significant offsets to mitigation costs, known as "environmental double dividends" and "economic double dividends". Environmental double dividends arise because actions to reduce greenhouse gas emissions also reduce other pollutants, toxics, acids, precursors to smog. This, plus other secondary benefits of mitigation action, results in economic benefits which have been shown in studies in Europe and the U.S. to offset 30 percent or more of the mitigation costs. If the reduction of emissions is achieved through a carbon tax or energy tax of some sort, "economic double dividends" can also arise through using the tax revenue to offset other more distortionary taxes and to increase investment. This combination of tax changes in cases studied resulted in reduced mitigation costs or even net benefits to a country's economy. (From WG3, Chapters 8 and 9)

  Increasing forested area can result in substantial CO2 concentration reductions.

• Studies suggest that as much as 15 to 30 percent of global energy-related emissions (on the basis of data for 1990) could be offset by additional carbon sequestration in forests for a period of 50 to 100 years.

  Actions implemented jointly with other countries can help to reduce costs.

• A program of "actions implemented jointly" between countries, would reduce overall costs of greenhouse gas mitigation.
• The (economic) value of better information including that on predictions of, impacts of, and responses to climate change is likely to be great.

  Research and development has potentially large economic value.

• Analysis of economic and social issues related to climate change, especially in developing countries where little work of this nature has been carried out, is also a high priority for research. Research and development of energy efficiency technologies and non-fossil energy options also offer high potential value.

  A portfolio of measures provide benefits over reliance on a single or few mitigation measures.

• A prudent way to deal with climate change is through a portfolio of actions aimed at mitigation, adaptation and improving our knowledge. The appropriate portfolio will differ for each country. The challenge is not to find the best policy today for the next 100 years, but to select a prudent strategy and to adjust it over time in the light of new information.

  A range of policy instruments are available.

• Individual countries that seek to implement mitigation policies can choose from among a large set of potential policies and instruments, including carbon taxes, tradable permits, deposit refund systems as well as technology standards, performance standards, product bans, direct government investment, and voluntary agreements. Public education on the sustainable use of resources could play an important part in modifying consumption patterns and other human behaviour.

CCPB/CGCP Comments

Canadian studies of potential for cost effective energy efficiency improvements are within the range quoted above (See summary in Canadian Options for Greenhouse Gas Emissions Reductions (COGGER), The Royal Society of Canada, 1993). The full range of measures, as examined by the Forecast Working Group of the Ministers, could be implemented at zero or slightly negative national costs, similar to studies in several other countries (see above). Canada has already adopted a portfolio approach as suggested.

6. The Longer Term Outlook

• Without mitigation actions, cumulative greenhouse gas emissions are projected to be, in the coming century, three to ten times those of the past 130 years.

  While there is a prospect of much greater greenhouse gas emissions in the future, stabilization of greenhouse gas emissions at 1990 levels is a useful first step.

• Present commitments of Framework Convention on Climate Change (FCCC), Annex 1 countries to aim to stabilize emissions at 1990 levels would, if continued beyond the year 2000, result in an 8 to 12 percent reduction below intermediate emission projections. (Special Report 1994)
• The ultimate objective of the U.N. FCCC is expressed in Article 2 and agreed by Parties to the Convention as: "...stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system".

  The ultimate objective of the Framework Convention is stabilization of concentrations, requiring major reductions in emissions over the next century.

• To achieve stabilization at levels between 25 percent greater than at present (450 ppmv), and up to 2 1/2 times pre-industrial values (750 ppmv) will require going much beyond stabilization of emissions. In fact, stabilization at 750 ppmv CO2 equivalent would require reductions, over the coming decades, to two-thirds of present CO2 emissions, while achievement of 450 ppmv CO2 equivalent would require global reductions to one-third of present emissions. (Draft Synthesis Report)
• The extent to which any of the impacts (Section 4) could be considered "dangerous" is country and region specific, and a difficult policy judgement. (CCPB/CGCP Comment)

  Adaptation measures will be needed as well as mitigation.

• Because of the long life-times of most greenhouse gases in the atmosphere, the earth is expected to warm further and sea level to continue to rise, even if measures were implemented which could immediately stabilize emissions or even concentrations. Thus, in addition to mitigation measures, countries should pursue actions to strengthen their capacity to adapt to some degree of climate change.
• Emissions can be reduced by switching from coal, to oil, to natural gas natural gas contains twice as much energy as coal per unit of carbon in the fuel. Large resources of natural gas exist in many areas. (Draft Synthesis Report)

  Technological options for emissions reduction will arise over the coming decades.

• Renewable energy sources are sufficiently abundant that they could technically provide all of the energy needs of the world at levels foreseen over the next century. Technical advances offer new opportunities and declining costs for energy from these sources. (Draft Synthesis Report)
• The removal and storage of CO2 from power-station stack gases is a feasible option to reduce GHG emissions, but will significantly increase the production cost of electricity. Depleted oil and natural gas fields could allow CO2 to be stored at relatively low cost. (Draft Synthesis Report)

  It is not too early to begin planning major changes as capital stocks are replaced.

• Appropriate long run signals are required to allow producers and consumers to adapt cost-effectively to constraints on greenhouse gas emissions and to encourage research and development. Failure to adopt policies as early as possible to encourage efficient replacement investments at the end of the economic life of plants and equipment (i.e. at the point of capital stock turnover) impose an economic cost on society. Implementing emissions reductions at rates that can be absorbed in the course of normal turnover are likely to be cheaper than enforcing premature retirement now.

CCPB/CGCP Comments

Canada has some special alternative energy opportunities.

• Canada's large reserves of natural gas and advanced development of some renewable energy technologies present special opportunities.

  Individuals must be encouraged to contribute to solutions.

• Achievement of the long term goal of the Climate Convention will require major shifts in energy and materials consumption, and supply patterns. The changes needed will also require major shifts in attitude and behaviour on the part of Canadians and the world's population. A much greater sense of stewardship of our small planet and of how the individual can help is an urgent need, and education programs should be enhanced.

  Countries in all parts of the world must be brought into mitigation efforts.

• Concerted global action will be required in the long term since, while two thirds of industrial emissions of CO2 are now coming from the industrially developed regions, over the next 25 years the presently developing countries will increase their share to slightly more than half the global total, under "business as usual" scenarios. This strongly implies the need for vigorous diplomatic negotiations under the FCCC, as well as action at home.