What is climate change?

Climate change is different from the changes in weather you see from day to day. It’s the kind of change in weather patterns your parents or elders may have noticed. You may have heard them say that winters aren’t as cold as they used to be, or that the ice is thinner on the lakes and in the Arctic. Scientists agree with them. The climate is changing. And it’s changing more quickly in the north than anywhere else.

Up until the last hundred years or so, the earth’s climate stayed much the same – for almost 10,000 years. Sure, there were some weird winters and really hot summers, and some cold stretches, but temperatures averaged out over the years, and you knew what to expect season to season. Little changed until about a century ago when the average temperature of the globe started to rise.

Over the last century, average temperatures in many Arctic regions climbed by as much as 5°C. The average worldwide temperature increased about 0.6°C.

Some scientists predict that, if these changes continue over the next 100 years, temperatures in the Arctic could rise by as much as twice the global average – and that’s expected to go up by 1.4° to 5.8°C.

That doesn’t sound like a problem, does it? Don’t people in the North deserve a break from long, cold winters? Maybe – but climate change means a lot more than warmer temperatures. It may change many of the things we value about the north - our environment and plants and animals. That makes climate change something worth checking out.

Greenhouse Gases – the Earth’s Blanket

To understand climate change, you have to know something about our atmosphere. Even though we can breath it and see through it, as far as the earth is concerned, the atmosphere works like a blanket. It’s made up of the air we breathe, plus small amounts of greenhouse gases (GHGs) that can trap heat like a warm, fleecy blanket. If you are chilly at night and cover up with a blanket, the warmth given off by your body gets trapped by the blanket and keeps you cozy. GHGs in the atmosphere do the same thing for the Earth. They trap some of the heat that the earth absorbs from the sun. This trapping of warmth is known as the ‘greenhouse effect.’

If the earth’s atmosphere didn’t have some greenhouse gases, heat would be lost to space and we’d have temperatures more like those on Mars. There, they go up to 37°C during the day - bathing suit weather - but down to, more than minus 100°C at night – tough to survive. The greenhouse gases in our atmosphere help make life on earth possible.

Too Many GHGs – Too Many Blankets

The amount of greenhouse gases we had in the atmosphere for about 10,000 years helped to keep the climate pretty much the same over that period of time. The earth’s environment, plants and animals (including us) adapted to that climate. A change in the amount of greenhouse gases could mean too much heat – or too little. That could affect us, and other life on the planet, by changing our environment.

Greenhouse gases need to be kept in a delicate balance. And more greenhouse gases could be too much of a good thing.

Why are we warming up?

Right now, human activities are tipping the balance of gases in the atmosphere. They are changing our climate. We are adding too many heat-trapping greenhouse gases to the atmosphere. The result is some very weird weather – more heat, more storms, more rain in some places and seasons, and more drought and unusual temperatures in others. This build-up of GHGs and what it does to our climate is sometimes called the “Enhanced Greenhouse Effect.”

So, what’s a few degrees?

A few degrees up or down don’t make a big difference day-to-day or even year-to-year. But over many years, it can be a big deal. During the last Ice Age, the earth’s average temperature was only 4° to 6°C cooler than it was for the last 10,000 years – that stable climate period we’ve talked about. During that Ice Age, a thick sheet of ice covered nearly all of Canada, and many plants and animals disappeared completely. So a few degrees can make a big difference over the long haul.

Where Are all these GHGs Coming From?

About 200 hundred years ago, humans began to develop faster ways of making and moving things. This period of time was known as the Industrial Revolution. The energy that made the revolution possible came from “fossil fuels.” These are fuels such as coal, and the diesel oil, furnace oil, kerosene and gasoline that come from petroleum.

When we use fossil fuels to run our cars, trucks, boats, airplanes and snowmobiles, we release greenhouse gases. We may also release GHGs when we heat our homes, run our industries, or generate electricity.

Let’s look at the major greenhouse gases and see why more of them are going into the atmosphere.

		Greenhouse Gases: Water vapour If you have gone into a bathroom after someone has showered and felt dampness in the air, then you have been surrounded by water vapour. Water vapour is part of the world’s water cycle. When water in rivers, lakes and oceans warms up, it evaporates. It becomes a gas – water vapour – and rises into the atmosphere. Sooner or later it comes back down as rain or snow. It collects in rivers, lakes and oceans as part of a natural cycle that will always continue. In the atmosphere, water vapour can form clouds. They can act like a blanket and trap heat close to earth. Clouds can also reflect heat from the sun back into space. There is more water vapour in our atmosphere than any other greenhouse gas. Carbon Dioxide (CO2) Carbon Dioxide (CO2) is the second most common GHG. Many natural processes put carbon dioxide into the atmosphere. Humans and animals breathe out carbon dioxide, and forest fires, volcanoes, and rotting trees and plants release it. Natural levels of CO2 in the air are important for life, but too much of it can tip the balance. If you have smelled the fumes from a car or snowmobile, you have also breathed in carbon dioxide (CO2) at the same time. Humans produce CO2 whenever we burn fossil fuels. And we burn them whenever we drive our vehicles, heat our homes, run our industries or fly airplanes. In many northern communities, we produce CO2 when we burn diesel to make electricity. The carbon dioxide produced by human activities is the main reason our climate is changing, and changing fast! Methane and Nitrous Oxide Methane and nitrous oxide are two other important greenhouse gases. They’re a small part of our atmosphere, but they can trap a lot of heat. In fact, methane is 21 times more powerful as a greenhouse gas than CO2, and nitrous oxide is 310 times more powerful! Large-scale farming and garbage dumps produce lots of nitrous oxide and methane. When farmers put nitrogen fertilizers on the soil to help plants grow, nitrous oxide is released. When cattle digest their food, they let out a lot of methane. With over three million cattle in Canada – that is a lot of gas! When food scraps in our garbage dumps rot, they produce methane, too. (When you don’t waste food and compost food scraps so air can mix with them, you cut down on methane production!)

Find out what climate change does:

As you can see, some GHGs occur naturally, but human activities are putting more GHGs into the atmosphere and changing our climate. To read more about the effects of GHGs and climate change, read Backgrounder 2 – Climate Change Impacts: A Changing World. To see what you can do to help slow down GHG production, read Backgrounder 3 – Climate Change Solutions: We can all help!

Want to know more?

Here are some websites to help you learn more about climate change and the greenhouse effect:

General

• EduGreen: http://edugreen.teri.res.in/explore/climate/climate.htm
• Government of Canada Climate Change Website: http://www.climatechange.gc.ca/english/index.shtml

Greenhouse Effect & GHGs:

• Cool Climate Kids’ Club (It’s a Gas!): http://www.coolclimate.org/itsagas.htm – A good explanation of GHGs.
• EPA Kids’ Site (Greenhouse Effect): http://www.epa.gov/globalwarming/kids/greenhouse.html
• Solar School: http://das.ee.unsw.edu.au/~solar/classrooms/1_1.html