According to recent research, the Earth has warmed an average of 0.5°C over the past 100 years. Climate change projections suggest that over the next century, further warming of 1°C to 3.5°C will occur with the largest warming expected to occur in the high latitudes. Here at home, analysis of temperature data in Canada reveals an increase of 0.9°C in the mean annual air temperature since 1948. This is an annual and national average. The warming has been greater in western Canada than in eastern Canada. General circulation models (GCMs) project an increase in our average annual temperature of about 4°C by the end of this century, with some regions warming more than others. Current projections have northern regions warming by as much as 7°C. It really doesn't seem like that big a change when we have variations in temperatures of 10°C to 20°C in a day_ But when this range is applied to the annual average, it becomes apparent that there will be changes in the climate we are now familiar with. What impact does that have on Canada's natural environment, and then our own human environment?

Canada is blessed with a wide variety of ecosystems within its borders, which are influenced by climate. Some sectors of the Canadian economy are based on this ecosystem wealth in natural resources. Changes in regional climate patterns may have positive and negative effects on these important ecosystems and resources.

• In the north, thawing of permafrost may cause massive terrain slumping, drainage of small lakes, and increased sediment loads in rivers. Warming and thawing of permafrost has important implications for many landscape processes and hazards such as increased terrain, slope, and coastal instability. These changes as well as associated alterations to surface hydrology, groundwater regimes, and surface vegetation have consequent socio-economic impacts for ecosystems, infrastructure, and development.
• There may be longer growing seasons and the extension of agriculture farther north (depending on the quality of the soil), but there will be real risks to agriculture such as moisture deficits, pests, disease, and fires.
• Water levels in lakes could change. This may threaten valuable shoreline and wetland habitats, have an impact on shipping and fisheries, and affect shoreline property values. Bottom-dwelling organisms contributing to healthy lakes could be threatened because it would take longer for lakes to be stratified, resulting in longer late-season periods of low oxygen conditions, which will damage fish populations.
• The number of heat-related deaths could rise because of higher summer temperatures, particularly in southern urban areas. Those with heart disease, respiratory conditions, the elderly, the very young, the poor, and the homeless would suffer most.
• Changes in temperature and precipitation may increase insect (vector)-borne diseases, causing increases or invasions into Canada of diseases such as West Nile virus, Lyme disease, and malaria.
• Canada's wetlands are important for fish and wildlife habitats, water storage, and as staging areas during migration of waterfowl. The ecology of these wetlands is very susceptible to water-level changes and could be seriously affected.
• In regions susceptible to spring flooding, changes in late winter-early spring thaw and precipitation patterns could result in increased frequency of ice jams and flooding. Damages caused by these events have already cost Canadians an estimated $60 million annually, and this cost will only increase.
• Climate change could alter the carbon cycle so that there is less dissolved organic carbon in surface waters. This would reduce a sort of 'water sunscreen', making the aquatic ecosystem more susceptible to impacts from ultraviolet (UV) radiation.
• There are projected changes in the occurrence and severity of extreme events (winter snow and ice storms, floods and droughts), which would have serious implications for the security and integrity of Canada's natural resources, social systems, and infrastructure with subsequent implications for the insurance industry and supporting public sectors.