The greenhouse effect is a warming of the Earth’s surface and lower atmosphere that tends to intensify with an increase in atmospheric carbon dioxide. The atmosphere allows a large percentage of the rays of visible light from the Sun to reach the Earth’s surface and heat it.
A part of this energy is re-radiated by the Earth’s surface in the form of long-wave infrared (IR) radiation, much of which is absorbed by molecules of carbon dioxide and water vapour in the atmosphere and which is reflected back to the surface as heat.
This is roughly analogous to the effect produced by the glass panes of a greenhouse, which transmit sunlight in the visible range but hold in heat. The trapping of this infrared radiation causes the Earth’s surface and lower atmospheric layers to warm to a higher temperature than would otherwise be the case.
Image Source: earthguide.ucsd.edu
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An increase in atmospheric concentrations of other trace gases such as chlorofluorocarbons (Freons), nitrous oxide, and methane, due again largely to human activity, may also aggravate greenhouse conditions and the IR active gases responsible for the effect are likewise referred to as greenhouse gases. They are mainly
CO2 – 52%, CH, – 24%, N2O – 18%, CFC’s – 6%.
Impact of Greenhouse Effect:
i. Such global warming would cause the polar ice caps and mountain glaciers to melt rapidly and result in appreciably higher coastal waters.
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ii. The increase in global temperatures is expected to result in other climate changes including rises in sea level and changes in the amount and pattern of precipitation.
iii. The rise in global temperature would also produce new patterns and extremes of drought and rainfall, seriously disrupting food production in certain regions.
iv. Effect on human health.
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v. Effects on agriculture.