KS3 Science Revision

The Earth's atmosphere is made up of different gases: 78% nitrogen, 21% oxygen and 0.04% carbon dioxide. However, the carbon dioxide level is rising due to pollution from burning fossil fuels and because of deforestation. These rising levels in carbon dioxide are causing the Earth's climate to rise. This is because carbon dioxide is a greenhouse gas, which means it traps heat in. When the sun's heat penetrates the Earth's atmosphere, some of it bounces back into space. But because of the increase in carbon dioxide, the atmosphere is getting thicker and isn't allowing sun rays to bounce back into space.