Forests are continuously been cut down for urbanisation. The loss of forest cover is the main cause for global warming and climate change. Gases such as carbon –dioxide, methane, nitrogen oxides which trap the solar heat get accumulated in the atmosphere. This causes a rise in the atmospheric temperature. The rise in atmospheric temperature is responsible for melting of the polar ice caps causing rise in the sea level. The rise in the sea water causes flood in many coastal regions. The pattern of annual rainfall also changes.Loss of forests also decreases the amount of fresh air.this leads to air pollution.