Extra greenhouse gases in our atmosphere are the main reason that Earth is getting warmer. Greenhouse gases, such as carbon dioxide (CO2) and methane, trap the Sun's heat in Earth's atmosphere.

It's normal for there to be some greenhouse gases in our atmosphere. They help keep Earth warm enough to live on. But too many greenhouse gases can cause too much warming.

The burning of fossil fuels like coal and oil increase the amount of CO2 in our air. This happens because the burning process combines carbon with oxygen in the air to make CO2.