Dear student. The ozone layer is a layer rich in ozone gas present in the earth's atmosphere. It lies between 10-40 km in the stratosphere layer of atmosphere. The atmosphere is very thin at polar regions as compared to equatorial regions. Thus the thickness of ozone layer is not uniform everywhere and varies from region to region. This layer absorbs most of the harmful UV radiation from the sun, thus protecting people on the earth. These UV radiations can cause skin cancer, genetic mutations and other harmful ailments. They also have harmful effect on vegetation. So the ozone layers acts as a protective cover for the earth. However, over the last few years, the ozone layer has depleted in may regions resulting in the formation of ozone holes. The use of chloroflorocarbons in aerosols and refrigerators, and their subsequent escape into the atmosphere, is blamed for making holes in the ozone layer over Antarctica and Arctic. This has resulted in harmful consequences, for plants, animals and human beings. 2.Warming of the Earth's surface by the substances such as carbon dioxide, water vapour which makes sun's energy reach to the ground but impede the way of energy to go back from earth's surface into the space leading to the higher temperature on the earth's surface. This is known as green house effect. Regards