Climate has been an important factor in Canada's history and will influence its future (Source : NASA)

Climate has been an important factor in Canada's history and will influence its future

Weather is the moment-to-moment state of atmospheric conditions, such as temperature, precipitation, winds, clouds, and air pressure. Climate is the expected or general pattern of weather for a place or region over extended periods of time. Recent unusual weather conditions have everyone talking about climate; it seems to make the news more than in the past.

There is increasingly stronger scientific proof, as in the latest assessment of theIntergovernmental Panel on Cimate Change (IPCC), that Climate Change is real, and that greenhouse gases resulting from human activities "haven contributed substantially to the observed global warming over the last 50 years".

Glaciers expand when climate cools and they shrink when it warms. The margin of Wedgemont Glacier, near Whistler, has retreated hundreds of metres over the last two decades, due mainly to melting during warm summers. Most glaciers around the world are shrinking, proof that climate is warming.

Wedgemont Glacier terminus - 1979 (Photograph courtesy of S. Irwin)

Wedgemont Glacier terminus - 1998 (Photograph courtesy of S. Irwin)

Over the past 140 years, Earth's atmosphere has warmed. The temperature increase has not been steady, but since the 1980s warming has accelerated. Scientists are concerned that we are entering a period of unprecedented global warming caused by humans.

Global temperature change (Environment Canada, 1993)

This map shows predicted differences in global surface air temperatures between 1910 and 2040. The greatest differences are predicted to be at high latitudes and in the interior of continents. Canada may experience more temperature change over the next several decades than most regions of the world.

Temperature Change (°C) 1910-2040 (Source :Environment Canada)

Temperature Change (°C) 1910-2040 (Source :Environment Canada)

Temperature Change (°C) 1910-2040 (Source :Environment Canada)

Environment Canada 1993 : A matter of degrees: a primer on global warming; The Environmental Citizenship Series, 89 p.