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What causes global warming?

Over the last 100 years the average temperature on Earth has gone up by 0.6 °C. It doesn’t sound much but some people are worried. This change in temperature is called global warming. If global warming carries on, many plants and animals living today on Earth (including us) could have problems surviving. It could mean more droughts and floods.

Global warming is caused by the greenhouse effect. It’s what keeps our planet at a nice comfortable temperature and the best way to explain how it works is to look at a greenhouse.

Why is it hot inside a greenhouse?

Have you ever noticed that it’s warmer inside a greenhouse than outside? This is because sunlight passes through the glass of the greenhouse and is soaked up by the plants and soil. The plants and soil warm up and give out heat. Although the greenhouse glass lets sunlight in, it doesn’t let all the heat out so some of the heat is trapped inside the greenhouse and it warms up.

What’s this got to do with our planet?

The air is made up of gases around the Earth (where we live). They are called greenhouse gases. The air is a bit like the glass of a greenhouse. It lets sunlight pass through easily but stops some of the heat getting out.

So when the rays of sunlight hit the Earth, it warms up. The Earth gives out heat but not all of it escapes into outer space. Some of it gets trapped close to the Earth and this warms up the air around us. Without the greenhouse gases, the Earth would be about 33 °C colder. It would not be warm enough for plants and animals to survive. The way that greenhouse gases keep the atmosphere at a nice temperature is called the greenhouse effect.