The air also keeps the Earth warm, specially the half turned away from the Sun. Some gasses – especially methane and carbon dioxide – work like a blanket to keep things warm. In the past, the Earth has been much warmer and much colder than it is now. Since people have grown used to the heat we have now, though, we do not want the Earth to be too much warmer or colder. Most of the ways people create electric power use burning kinds of carbon—especially coal, oil, and natural gas. Burning these creates new carbon dioxide and can cause more warming. A large discussion is going on now about what people should do about the Earth's latest warming, which has gone on for about 150 years. So far, this warming has been good for people: plants have grown better and the weather has been better than when it was colder before. Some people who learn about science, though, say that many bad things will possibly come about if the warming goes on.