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Earth's atmosphere keeps much of the Sun's energy from escaping into space. This process, called the greenhouse effect, keeps the planet warm enough for life to exist.

Here's a closer look at how it works:

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Energy radiates from the Sun. When the Sun’s energy reaches Earth’s atmosphere, some reflects back out into space, some is absorbed by the atmosphere, and some (50%) travels down to the surface. 

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Some of the energy that reaches Earth's surface is reflected back out into space. The Earth absorbs the rest. The absorbed energy radiates from the surface as heat energy. 

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Certain gases in the atmosphere absorb the heat energy. This causes the atmosphere near Earth’s surface to warm, reaching temperatures that allow plants and animals (including humans) to live. This process is called the greenhouse effect, and the heat-absorbing gases in the atmosphere are called greenhouse gases, because the atmosphere holds in heat like the clear walls of a greenhouse.

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Some of the main greenhouse gases are carbon dioxide, water vapor, and methane. The more of these gases there are in the atmosphere, the warmer Earth gets. This process has been happening for billions of years. 

In recent history, human activity is throwing off the balance of greenhouse gases. To get energy or electricity, we burn fossil fuels like coal, oil, and natural gas. This has been increasing the concentration of carbon dioxide and other greenhouses gases in the atmosphere. The more greenhouses gases we put into the atmosphere, the more heat they absorb, leading to climate change .

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Build your own miniature greenhouse to see the greenhouse effect at work.