Fossil Fuels, the Atmosphere and Climate Change

A blanket for the whole planet

On a cold winter night, you pull a blanket over yourself. The blanket doesn't make heat, but it traps the heat from your body and keeps you warm. Add a second thick blanket and you might get too hot.

Earth has a kind of blanket too: the atmosphere. In this lesson you'll find out how burning fossil fuels is making that blanket "thicker", and why that matters.

What happens when fossil fuels burn

Coal, oil (gasoline, diesel) and natural gas store chemical energy. They are made mostly of carbon, from the ancient living things they formed from.

When they burn in a car engine, a furnace or a power station, their chemical energy changes into heat, light and motion. But burning also releases a gas called carbon dioxide into the air. Carbon that was buried underground for millions of years goes into the atmosphere in a very short time.

Natural gas is mostly a gas called methane. When methane leaks into the air without burning, it is also a gas that traps heat.

The greenhouse effect

Sunlight passes through the atmosphere and warms the Earth's surface. The warm Earth then gives off heat. Some of that heat escapes to space, but some is trapped by greenhouse gases, like carbon dioxide, methane and water vapour.

This is called the greenhouse effect, and we need it! Without any greenhouse gases, Earth would be far too cold for most living things.

The problem is too much. Burning fossil fuels keeps adding more carbon dioxide. More greenhouse gases trap more heat, like adding extra blankets. Scientists have measured that the amount of carbon dioxide in the atmosphere has gone up, and that Earth's average temperature is rising. This is changing Earth's climate.

Weather or climate?

Weather is what the air is like today: a snowstorm on Tuesday, a sunny Saturday.

Climate is the usual weather of a place over many years. Ontario's climate has cold, snowy winters and warm summers.

Climate change is a long-term change in that usual pattern. One very cold week does not mean climate change isn't happening, because climate is about many years, not one week.

Some changes scientists have observed in Canada

• On average, temperatures are getting warmer, and winters are warming fastest.
• Sea ice in the Arctic is shrinking, and permafrost (ground that used to stay frozen all year) is thawing in many places.
• These changes affect people. For example, many Inuit travel and hunt on sea ice, and thinner or less predictable ice can make travel more dangerous.
• Climate change can make some events, like heat waves and wildfires, more likely.

Plants help

Trees and other plants take in carbon dioxide from the air to make their food. Forests and wetlands store a lot of carbon. When forests are cut down and burned, that carbon goes back into the air.