The earth is enveloped by a blanket of gases called atmosphere. Some of the these gases like carbon dioxide, methane and water vapour have the property to trap the sun's heat. These gases do not allow the heat to escape into the space. This heat keeps the earth warm. This is called global warming and these gases are called green house gases. But when the concentration of these gases increase in the atmosphere, it leads to rise in the atmosphere.This result into melting of polar ice rise in sea level and submerging of low lying areas near the sea. To reduce the effects of global warming, we should reduce the release of green house gases into the environment. One of the important step in this direction is to plant more and more trees because trees are good absorbers of carbon dioxide, the main green house gas.