Burning of fossil fuels releases various types of gases like carbon dioxide, oxides of sulphur, oxides of nitrogen etc. Carbon dioxide is a greenhouse gas and when released in large quantities formed as a layer on our atmosphere causing greenhouse effect. It traps the sunlight rays inside the surface of earth thus the temperature of earth increases. Hence the consequence of greenhouse effect is global warming. Besides the oxides of sulphur, oxides of nitrogen etc. which are released into the atmosphere are the main causes of acid rain.