A natural process of warming of the Earth occurs by the sun. Firstly the sun's rays enter the Earth's atmosphere (a layer of gases made up of mainly oxygen and nitrogen and some carbon dioxide). About half of the heat is absorbed by the Earth's surface, warming it. Some of the heat bounces off the Earth and escapes from the atmosphere but the rest of the heat is caught by the gases in the atmosphere but the rest of the heat is caught by the gases in the atmosphere, acting like a blanket to ensure the temperature doesn't drop dramatically.

The 'greenhouse gases', made up primarily of carbon dioxide, are caused predominately by burning coal, oil and gas (we burn oil and create carbon dioxide when we drive our car, a process that will be discussed in another post). These gases thicken the atmosphere which allows the heat in, as per the natural process, but do not allow the same amount to escape which increases the warmth of the atmosphere. The more carbon dioxide that is released into the atmosphere from cars, buses and trucks, the more heat will be trapped.