Meaning of Global Warming :-
Global Warming is an increase in the earth's temperature due to the use of fossil fuels and other industrial process leading to a build-up of "greenhouse gases" (carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons) in the atmosphere. Air pollution traps more heat in the atmosphere, rendering the earth more warmer. This effect is called "global warming".
Causes of Global Warming :-
The main causes of Global Warming is greenhouse gases. These are carbon dioxide, methane, nitrous oxide, chlorofluorocarbon and ozone. Generally these gases are present in rather small amounts but play a major role in the heat balance of atmosphere due to their capacity to absorb infrared radiations. By preventing long wave thermal radiation from radiating out of the atmosphere, the temperature of the atmosphere thus increases considerably.
About 51% of the solar energy reaching the earth is absorbed by the earth's surface, which increases its temperature. The rest of the heat radiates back to the atmosphere. Some of the heat is trapped by greenhouse gases (GHGs), mostly carbon dioxide. Normally, carbon dioxide and other gases that surround the plant let the radiation from the sun reach the earth, but prevent some of the heat from being reflected back out again. Without these greenhouse gases, the earth would be far cold and largely covered with ice. The problem comes when the amount of these gases exceeds a certain limit. The average surface temperature is about 15℃. This is about 33℃ higher than it would be in the absence of the greenhouses effect. Without such gases, most of the earth's surface would be forzen with a mean air temperature of 18℃.
Human activities during the last few decades of industrialization and population growth have polluted the atmosphere to the extent that it has begun to seriously effect the climate. By burning large amount of fossil fuels we release huge quantities of carbon dioxide into the atmosphere. Concurrently, deforestation also release carbon trapped in the tissues of the trees. At the same time, loss of trees reduces the earth's capacity to absorb carbon dioxide through photosynthesis. Natural process like volcanic eruptions and earthquake-induced fires also contribute to carbon dioxide emissions. The carbon dioxide emissions. The carbon dioxide in the atmosphere has increased by 31% since pre-industrial times, causing more heat to be trapped in the lower atmosphere. If emission continues to rise by about 0.50℃ rate, a rise of 1.5℃ to 4.5℃ is likely by 2030. In 1995, the Inter-Governmental Panel on Climate Change (IPCC) (a group of the world's leading scientists), predicted that global warming would raise temperature by 3.5℃ - 10 ℃ during it could be much greater.
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