Global warming occurs when carbon-di-oxide (CO₂) and other air pollutants and greenhouse gases collect in the atmosphere and absorb sunlight and solar

audiation that have bounced off the earth's surface. Normally, this radiation would escape into space but these pollutants, which can last for years to centuries in the atmosphere, trap the heat and cause the planet to get hotter. That whats known as the greenhouse effect.

(i) Global temperature increase: It is estimated that the earth's mean temperature will rise between 1.5 to 5.5°C by 2050 if input of greenhouse gases continues to rise at the present rate.

(ii) Rise in sea level: With the increase in global temperature sea water will expand. Heating will melt the polar ice sheets and glaciers resulting in further rise in sea level.

Life of millions of people will be affected by the sea level rise who have built homes in the deltas of the Ganges, the Nile, the Mekong, the Yangtze and the Mississippi rivers.

(iii) Effects on human health: The global warming will lead to changes in the rainfall pattern in many areas, thereby affecting the distribution of vector-borne

diseases like malaria, filariasis, elephantiasis etc.

(iv) Effects on agriculture: There are different views regarding the effect of global warming on agriculture. Tropical and subtropical regions will be more

affected since the average temperature in these regions is already on the higher side. Even a rise of 2°C may be quite harmful to crops. Soil moisture will decrease and evapo-transpiration will increase, which may drastically affect wheat and maize production.