Greenhouse gases are naturally present inthe atmosphere and maintain temperatures on earth that are favorable to life. Too much greenhouse effect, however, leads to warming of the global climate. In the space of a century, world energy demand-used for electricity,heading,and trasportation,for example- has increased by a factor of thirteen. Most of this energy comes from oil, gas,and coal,which produce greenhouse gases.

By making a point of switching off lights that do not need to be on we can all save energy, especially when leaving a room, and by using daylight instead wherever possible. The less that electricity is used, the less energy is needed, and therefore less greenhouse gas is pumped into the atmosphere.