The greenhouse effect is a natural process that occurs when gases in Earths atmosphere trap the Suns heat, making Earth much warmer than it would be otherwise. The process works like a greenhouse, where gases in the atmosphere, such as carbon dioxide, trap heat similar to the glass roof of a greenhouse. During the day, the Sun shines through the atmosphere, and Earths surface warms up in the sunlight. At night, Earths surface cools, releasing heat back into the air. But some of the heat is trapped by the greenhouse gases in the atmosphere, which keeps our Earth a warm and cozy 58 degrees Fahrenheit (14 degrees Celsius), on average. Greenhouse gases occur naturally and are part of our atmospheres makeup, and they are crucial to keeping our planet at a suitable temperature for life. However, human activities are changing Earths natural greenhouse effect by adding more greenhouse gases to the atmosphere, mainly through the burning of fossil fuels that add carbon dioxide to the air. Too much of these greenhouse gases can cause Earths atmosphere to trap more and more heat, causing Earth to warm up.