Canada’s climate is changing, according to Linda Mortsch, a researcher with the Meteorological Service of Canada.
Mortsch presented findings from a report that examined twelve indicators of climate change on January 19 at the U of T Earth Sciences Centre. These indicators-ranging from polar bear body mass to the size of glaciers-provide strong evidence that climate change is underway in Canada.
According to the report, which was commissioned by the Canadian Council of Ministers of the Environment (CCME), global warming has resulted in higher temperatures and increased precipitation in many parts of Canada. These changes are having a significant impact on our environment.
Other researchers concur that the evidence of global warming is now compelling.
“Among climate scientists, the consensus is that climate change is real,” says William Gough, a professor of Environmental Science at U of T. “The climate of Canada has changed over the last 100 years.”
Mortsch noted that the average temperature in southern Canada-the region lying south of the 60 parallel-increased by 0.9 degrees Celsius between 1900 and 1998. Between 1950 and 1998 the average increase in temperature for all of Canada was 0.3 degrees. The United Nations Intergovernmental Panel on Climate Change has reported that the Earth’s average temperature increased by roughly 0.6 degrees during the 20th century.
According to U of T professor Ted Munn, most specialists now agree that the changes in the Earth’s climate are not simply the result of natural variability, as some skeptics contend. He noted that since 1990, the average world temperature has risen significantly.
Higher temperatures are having wide-ranging effects across Canada. The area in the arctic covered by permanent sea ice has decreased. Glaciers and icefields in British Columbia have lost a significant amount of their mass. River and lake ice is breaking up earlier in much of the country.
Most of the country also receives more precipitation. Southern Canada now gets about 5 to 30 per cent more precipitation than it did in 1900. There have also been significant precipitation increases in the central arctic over the last 50 years.
The changing climate has also affected plants and animals. Early breakup of sea ice in western Hudson Bay has caused polar bears to leave the ice earlier in the summer. With less time to build up fat reserves on the ice, and more time on land-where they eat less-polar bears are gradually losing weight, and their birth rate is declining.
Despite the consensus that global warming is a reality (and that it is being caused by greenhouse gas emissions arising from human combustion of fossil fuels), researchers have yet to fully understand how climate change will affect different parts of Canada.
It is now apparent that the effects of climate change can vary significantly across regions. For example, the west and northwest have been getting warmer over the last 50 years, while parts of the northeast and the Maritimes are actually getting cooler.
Moreover, some of the effects of global warming-such as increased precipitation, melting glaciers, or changes in ocean circulation-may create feedback effects, causing unforeseen changes in some areas. One researcher noted that over the next 50 years, it is possible that deep ocean currents in the North Atlantic (mentioned in the film The Day After Tomorrow) will slow down, which could cause cooling in the UK and Scandinavia.
According to Andrew Weaver, a professor and Canada Research Chair in Atmospheric Science at the University of Victoria, “The interesting questions concern how climate change will change regional weather and how so-called feedback mechanisms may affect the magnitude of these changes.”