The atmosphere is the air around the surface of the earth. It is made from a mixture of gases. We need it for animals and plants to survive.
The atmosphere is made of 78% Nitrogen and 21% Oxygen. The last 1% are called ‘greenhouse gases’. Greenhouse gases act like a blanket, trapping heat. These gases are:
Carbon dioxide (CO₂)
The earth’s atmosphere has always had greenhouse gases. Without them, the earth would be much colder. When the sun shines, the heat from the sun reaches the earth. Some of the sun’s heat gets trapped in the atmosphere. Some of it gets reflected back into space. The heat that gets trapped in the atmosphere warms the earth up.
Before the industrial revolution, the number of greenhouse gases in the atmosphere stayed the same, keeping the earth just the right temperature for all the plants and animals to live happily.
This is known as the ‘Natural Greenhouse Effect’.
Some things that people do now (e.g. Burning of fossil fuels, deforestation, food production and draining peat bogs) are increasing the amounts of greenhouse gases in the atmosphere. The more greenhouse gases that go into the atmosphere, the more heat is trapped and the warmer our earth becomes. The heating of the earth through human activities is called the ‘Enhanced Greenhouse Effect’ or ‘Global Warming’.
The graph shows how throughout time, the temperature has risen higher and higher.