The temperature of our planet is dependent on the balance of energy entering and leaving the Earth and its atmosphere. When the sun shines on the Earth, some of the sun's energy is absorbed by the land and water, and is released back into the air as heat. Greenhouse gases in our atmosphere trap some of this heat, thereby regulating the Earth's temperature and making it habitable for humans. (Greenhouse gases include carbon dioxide, methane, nitrous oxide and ozone.)
This balance is disturbed when people burn fossil fuels (like coal, oil and gas) for electricity, transportation and industry. Burning fossil fuels means that additional carbon dioxide is released into the atmosphere. As carbon dioxide increases, the atmosphere traps more heat. This is called "the greenhouse effect" or "global warming" because it is causing the Earth's overall temperature to increase. "Global climate change" is what scientists call the long-term changes in climate—like rising sea level and shifting weather patterns—that result from a higher global temperature.
Global climate change is a big problem, and scientists around the world are trying to figure out how to reduce the amount of carbon dioxide we release into the air. But even though the problem is big, each person can still make a difference. An individual's carbon footprint is the amount of carbon dioxide he or she emits into the air through everyday activities like driving or riding in a car or bus, playing video games and turning lights on and off. Every time a person makes an effort to reduce his or her carbon footprint, less carbon dioxide is put into the air—and that helps to lessen the impact of global climate change.