Green House Effect
Carbon dioxide and water vapour absorb infrared radiation coming to the earth and partly reflect it back to the earth's surface. Due to this, the surface of the earth gets heated up. This phenomenon of heating up of the surface of the earth is called green house effect. Due to deforestation, the quantity of carbon dioxide in the atmosphere is increasing. When fossil fuels are burnt oxygen levels do not change much, but carbon dioxide levels are very much affected. Because of this, global climate is affected. A 50% increase in carbon dioxide level increases the surface temperature of the earth by 30C. If there is a 10 C increase in the temperature, the following bad effects are predicted:
- The ice caps of the polar region melt, thereby increasing the level of the seawater by 90 cm. Due to this many countries like Netherlands, Bangladesh, Maldives etc. may get submerged. Other places like England, Miami in U.S., Shanghai in China, Chennai & Goa in India, may also get affected very badly.
- Due to global warming, the rate of evaporation of water from the seas, rivers, ponds will increase. This leads to untimely rains, cyclones and hurricanes.
- Agriculture sector will be badly affected due to fast evaporation of surface water. There will be a shortage in the supply of water for agricultural purposes.
CFC 17%; *O3 18%; NO 4%; Water vapour 2%
[Ozone in the stratosphere acts a protective layer, but harmful if it is present in the troposphere]