Global warming is defined as the overall increase in the temperature of the Earth.

Causes of global warming:

(i) It is caused due to increase in the concentration of greenhouse gases in the atmosphere. The greenhouse gases trap the infrared heat reflected back by the earth’s surface and does not let the heat escape the atmosphere thereby increasing the temperature. Examples of greenhouse gases are-Methane, Carbon dioxide, CFS’s, etc.

(ii) Over exploitation of fossil fuels releases excessive amounts of CO₂ in the atmosphere along with oxides of Nitrogen and sulphur.

(iii) Usage of CFC’s in aerosols, refrigerator coolants etc.

(iv) Deforestation of a very large scale causes disturbance in the CO₂-O₂ balance I atmosphere created by pants through photosynthesis.

Effects of global warming:

(i) Global warming has caused change in the seasonal patterns, rainfall etc. making the occurrence of floods, droughts more rapid.

(ii) Melting of polar ice caps.

(iii) Rise in the sea level which has caused submerging of various islands and low lying areas.

(iv) Many species of organisms (plants, animals and microbes) sensitive to temperature change may vanish leading to loss of biodiversity.

Various measure to control global warming:

(i) Usage of alternative sources of energy- renewable sources such as solar, wind energy, over traditional fossil fuels will decrease the CO₂ emissions.

(ii) Afforestation may increase the taking in of CO₂ by the plants thus reducing its levels in the atmosphere.

(iii) Reduce the usage of CFC’s and instead use its alternatives.