Some scientists believe the Earth is warming up.
While that may be hard to believe in the middle of a Wisconsin winter, if it's true it could mean big changes for our planet. Light from the sun warms land, water, and air. In turn, the warmed-up land, water, and air give off heat, which rises up toward the sky. Gases in the Earth's atmosphere capture some of that heat and prevent it from escaping into space. Without heat trapping, the earth's surface would be about 60 degrees Fahrenheit colder than it is now.