The Atmosphere

I know that to some of you, the Arctic may look strange and forbidding, almost like another planet. But it's really quite a friendly place.

If we decided to go explore Mars instead, now that would be another story completely! Oh, you'd be fine out there in the daytime. All you'd need is an airpack, a bathing suit and a lot of sunscreen.

But at night, the warmest caribou parka wouldn't do you much good since the temperature plunges from about 200 Celsius to a nippy minus 1250! Why so cold? The secret is atmosphere. The trouble is, Mars hasn't got much. After a Martian sunset, there's very little to keep the day's heat from zinging back into space. But down here on Earth, we've got plenty of atmosphere which acts like a giant greenhouse to give our planet more livable temperatures, day or night.

Greenhouse Gases

Most of our atmosphere is made up of nitrogen and oxygen gas. Thank goodness for these! They're the breath of life! But what keeps us from freezing or frying are the atmosphere's greenhouse gases such as water vapour, carbon dioxide, methane and nitrous oxide. Of these, it's carbon dioxide that steals the show in the climate change story.

Carbon dioxide is especially good at absorbing the heat energy that's bouncing off the Earth's surface - just like greenhouse glass. Some heat is absorbed, some escapes into space. It's like a teeter-totter. With more carbon dioxide, the climate warms. With less carbon dioxide, the climate cools.

Since green things first covered the Earth, plants have been keeping this delicate balancing act in check by absorbing carbon dioxide from the air. When they die and rot away, a lot of that stored carbon is slowly released back into the air. Forest fires speed this process up. So does burning things like coal, gas and oil. These too came from plants millions of years ago - that's why they call them fossil fuels. Even without burning any fuel, you make a carbon contribution with every breath you exhale.

Over the past 400,000 years, the carbon dioxide teeter-totter dipped low enough to cool the world's climate by five degrees celsius. If you like numbers, that translates into a carbon dioxide dive from 275 parts per million to 220 - or a loss of 20%. That's all it took to trigger an ice age!

Increasing Carbon Dioxide Levels

But those days seem to be over. Since then, the world's carbon dioxide level has never been higher and things are heating up faster. And guess who's since been helping turn up the thermostat? Good old Homo sapiens!

During the last two centuries, humans have given the natural greenhouse effect a big boost by burning up fossil fuels like there was no tomorrow. All that extra carbon is being pumped into the air way faster than it can be absorbed. And when the composition of the air changes, all the changes, all the other elements that support life change with it.

The result?

Seasons are changing. Ice caps are melting. Oceans are warming. Plant and animal ranges are shifting - all because the climate is changing like never before. And it turns out there's no better place to look for evidence of this change than right here in my arctic backyard.

Come ask the people who live here how they see climate change and what they're doing about it. Find out what scientists are discovering. See how people at the four corners of the world are dealing with similar problems while learning what you can do to cut your greenhouse gas contribution.

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