Earth is slowly getting warmer. Most scientists believe that people are helping to cause this change. But how can people cause Earth to warm?
Have you ever seen a greenhouse? The glass walls let in light so plants can grow. Because the walls also hold in heat, a greenhouse becomes very warm.
Earth and its atmosphere act like a greenhouse. Light from the sun passes through the atmosphere and warms Earth. Much of this heat escapes back into space. But such gases in the atmosphere as carbon dioxide act like greenhouse walls. These so-called “greenhouse gases” trap heat in the atmosphere. This is called the greenhouse effect.
Our cars and factories burn fuels that release greenhouse gases. These gases are building up in the in atmosphere. Most scientists believe that the buildup of gases is causing Earth to warm. They fear that our planet will become much warmer in the next 100 years. This problem is called global warming.
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