Greenhouse gases like carbon dioxide exist in our atmosphere. They are called
greenhouse gases because they cause the atmosphere to act like the glass
of greenhouse. That is, the sun’s rays pass through the atmosphere and heat
up the earth, and then the greenhouse gases prevent the heat from leaving.
Human activities like burning fossil fuels, are putting more greenhouse gases in
the atmosphere. The extra greenhouse gases act like an extra layer or a blanket
by trapping even more heat and warming the earth.