What is Climate Change?

Climate Trends

An analysis of temperature records shows that the Earth has warmed an average of 0.6°C over the past 100 years. There appears to have been a warming until the early 1940's then a moderate cooling until the mid 1970's, followed by a renewed and pronounced warming continuing through the present. The 1990's was the warmest decade on record. (In fact, ice core and other proxy data indicates that the 1980's and 1990's were the warmest decades of the past millennium).

Night-time temperatures over land have generally increased more than daytime temperatures. Regional changes are also evident. For example, recent warming has been greatest over the mid-latitude continents in winter and spring, with a few areas of cooling such as the North Atlantic Ocean. Precipitation has increased over land in high latitudes of the Northern Hemisphere, especially during the cold season.

This is consistent with predictions of climate change due to an enhanced greenhouse effect and increased aerosols. Yet, it could also be within acceptable limits for natural temperature variation.

Canada has warmed by 1.0°C over the last century. However this warming has not been consistent throughout the entire time span. The 1980's and 1990's were undisputedly the warmest decades on record in Canada. The warming that has been observed in Canada over the past century is real and significant though its intensity has varied from decade to decade, from region to region, and from season to season.