how is global warming affecting the water cycle of earth........??

Asked by sonia_23 | 8th Jan, 2010, 07:05: PM

Expert Answer:

Increases in anthropogenic greenhouse gases resulting from the burning of fossil fuels and the deforestation of forests have altered the composition of the atmosphere, resulting in an increase in the amount of heat energy trapped at or near the Earth's surface. This enhancement of the greenhouse effect is increasing surface temperatures while provoking other changes in climate as well. Studies indicate that roughly 80% of the net additional heat energy trapped at the Earth's surface by the build-up of greenhouse gases is transferred back to the atmosphere through increased evaporation of water from the land and ocean, where condensation returns the additional heat to the atmosphere causing warming, while enhancing precipitation. The remaining 20% of the net additional heat from the enhanced greenhouse effect contributes directly to warming of the surface and the lower atmosphere. Both contributions lead to a general warming of the Earth's climate and to an increase in the water vapor in the atmosphere, thereby further enhancing the greenhouse effect.

Thus, the trapped heat energy serves to accelerate the cycling of water (as water vapor) from the surface to the atmosphere, and enhances the transfer of the water vapor back to the surface as rain and snow (condensation and precipitation). The increased availability of water vapor in the atmosphere also leads to a significant increase in the energy available to drive storms and associated weather fronts, therefore affecting rainfall rates, precipitation amounts, storm intensity, and related runoff. There is compelling observational evidence that the Earth's hydrologic cycle has intensified during the past century as global temperatures have increased.

Answered by  | 11th Jan, 2010, 07:52: AM

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