Temperatures on the rise

Canadians today enjoy a mean annual temperature that is approximately 1^oC higher than at the beginning of the 20th century. Furthermore, during the last two decades, the Earth has experienced a record number of very warm years. In Canada, the 20th century is the warmest on record, the 1990s the warmest decade, and 1998 and 2001 the hottest years of the past 1,000 years. In the Great Lakes–St. Lawrence River Basin, the winter of 2001/02 was 4.8°C warmer than average, setting a new record. During the summer of 2001, the number of days in central and eastern Canada with maximum temperatures in excess of 30°C was about 2 to 4 times the average for 1961 to 1990.

The Intergovernmental Panel on Climate Change (IPCC) has concluded that global warming is a result of a combination of natural and human factors but that most of the warming during the past 50 years was likely due to human influences.

A thick veil of gases cloaking the planet contains gases that hold in the warmth the Earth produces. These are the greenhouse gases that are produced naturally by the forests, oceans, soils, swamps and all life forms. Without their beneficial effect, the mean global temperature, which is currently 15^oC, would be close to that of the moon, namely −18^oC.

But since the Industrial Revolution, and more notably since the increase in the use of fossil fuels, modern societies have been releasing more of these gases into the atmosphere (in particular, carbon dioxide, methane and nitrous oxide). They have also introduced new gases—chlorofluorocarbons or CFCs—into the atmosphere, where they exhibit an extremely high capacity for heat retention.

The intensification of the greenhouse effect and the resulting global warming could have serious consequences in some regions of the world. Melting glaciers would cause sea levels to rise, imperilling a number of low-lying coastal areas. In Canada, the greatest impact would be on the Far North, where winters would be shortened. Widespread thawing of the permafrost could also cause land cave-ins. In southern Canada, lake and groundwater levels are expected to drop. There could also be outbreaks of diseases such as malaria, which are presently confined to the tropics.

In December 1997, Canada and more than 160 other countries met in Kyoto, Japan, and agreed to targets for reducing greenhouse gas (GHG) emissions. The Kyoto Protocol is the agreement that set out those targets and the options available to countries for achieving them. Canada's target is to reduce its GHG emissions to 6% below 1990 levels by the period from 2008 to 2012.

With the ratification of the Kyoto Protocol in December 2002, the Government of Canada made climate change a national priority and has been working closely with Canadians and the global community to meet this challenge.

The average global temperature at the Earth's surface has warmed by about 0.6°C since the late 19th century. Without co-ordinated global action to reduce greenhouse gas emissions, the global average surface temperature relative to 1990 is expected to rise significantly by the year 2100. Even if greenhouse gas concentrations are stabilized, temperatures will continue to rise for centuries after stabilization because of the delay in ocean response.