(Source: NASA)

Front-page news

Weather is the moment-to-moment state of atmospheric conditions, such as temperature, precipitation, wind, clouds, and air pressure. Climate is the expected or general pattern of weather for a place or region over extended periods of time. Climate never used to make the news, but unusual weather conditions in recent years seem to have everyone talking about it now.

? Experts have different opinions about the future of our climate. How do you determine who is right?

Heating up fast: the 1980s and 1990s

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 (Source: Environment Canada, 1993)

A much different future

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 1910-2040 (Source: Environment Canada)

Nature's thermometers

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 (Steve Irwin)

Wedgemont Glacier terminus - 1998 (Steve Irwin)

Did you know?
The twentieth century was the warmest century of the last 1000 years, and the 1990s was the warmest decade of that century.

References

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