![A graphic of a spherical shape, with blurred margins, containing the number one.](/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/01/4568037-1-eng-US/01_full_495.gif 44w,/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/01/4568037-1-eng-US/01_full_990.gif 44w,/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/01/4568037-1-eng-US/01_full_1468.gif 44w,/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/01/4568037-1-eng-US/01_full_1980.gif 44w,/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/01/4568037-1-eng-US/01_full_2475.gif 44w)
The atmosphere allows about half of the Sun's heat energy (50%) to reach Earth's surface.
![A graphic of a spherical shape, with blurred margins, containing the number 2.](/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/02/4568041-1-eng-US/02_full_495.gif 44w,/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/02/4568041-1-eng-US/02_full_990.gif 44w,/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/02/4568041-1-eng-US/02_full_1468.gif 44w,/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/02/4568041-1-eng-US/02_full_1980.gif 44w,/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/02/4568041-1-eng-US/02_full_2475.gif 44w)
About a third of the Sun's energy (30%) is reflected back into space.
![A graphic of a spherical shape, with blurred margins, containing the number 3.](/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/03/4568045-1-eng-US/03_full_495.gif 44w,/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/03/4568045-1-eng-US/03_full_990.gif 44w,/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/03/4568045-1-eng-US/03_full_1468.gif 44w,/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/03/4568045-1-eng-US/03_full_1980.gif 44w,/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/03/4568045-1-eng-US/03_full_2475.gif 44w)
The rest of the Sun's energy (20%) is absorbed by greenhouse gases in the atmosphere, like carbon dioxide, water vapor, and methane.
![A graphic of a spherical shape, with blurred margins, containing the number 4.](/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/04/4568049-1-eng-US/04_full_495.gif 44w,/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/04/4568049-1-eng-US/04_full_990.gif 44w,/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/04/4568049-1-eng-US/04_full_1468.gif 44w,/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/04/4568049-1-eng-US/04_full_1980.gif 44w,/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/04/4568049-1-eng-US/04_full_2475.gif 44w)
Greenhouse gases in the atmosphere also absorb and hold some of the heat energy radiating back from Earth's surface.
![A picture of Earth with several arrows indicating the direction of solar energy reaching Earth and being deflected or absorbed by our atmosphere.](/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/greenhouse_chart/4568053-1-eng-US/greenhouse_chart_full_495.gif 495w,/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/greenhouse_chart/4568053-1-eng-US/greenhouse_chart_full_990.gif 510w,/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/greenhouse_chart/4568053-1-eng-US/greenhouse_chart_full_1468.gif 510w,/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/greenhouse_chart/4568053-1-eng-US/greenhouse_chart_full_1980.gif 510w,/var/ezflow_site/storage/images/media/amnh/images/explore/ology-images/climate-change/what-is-the-greenhouse-effect/greenhouse_chart/4568053-1-eng-US/greenhouse_chart_full_2475.gif 510w)
This process has been happening for billions of years. After all, greenhouse gases occur naturally in the atmosphere. But 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 releases carbon dioxide and other greenhouses gases into the atmosphere. The more greenhouses gases we put into the atmosphere, the more heat they absorb—and the warmer our Earth becomes. This is called climate change .