Today, global warming is regarded one of the most urgent issues human beings should solve. Global warming refers to the phenomenon that the temperature of the earth's surface rises gradually. It is not an emerging issue in the modern times. The average temperature of the earth has long risen little by little. However, in recent days, global warming became an object of concern with its speed. Now, the earth is confronting rapid rising temperature resulting from the artificial factors. There is no apparent cause identified but the most attractive claim regards increase of the greenhouse gas including carbon dioxide and methane as the primary cause.