Thursday, April 29, 2010

Wet regions in the tropics get even wetter

Richard P. Allan in Environmental Research Web: Satellite measurements indicate that wet regions in the tropics are becoming progressively wetter, at the expense of dry regions. Observed changes in tropical rainfall are at the upper limit of simulations obtained using detailed computer climate models, something that will have implications for future climate change predictions made by these same models.

Some of the most important consequences of a warming climate are linked to the global water cycle, which includes evaporation at the Earth's surface, transport of vapour by winds, condensation of droplets as clouds and eventual precipitation (rain and snow). Runoff through river systems at the surface is also included.

Climate models – detailed mathematical representation of the Earth's atmosphere, oceans and land surface – have long predicted increases in the amount and intensity of precipitation in a warming climate, relating to subtle changes in energy flows between the atmosphere and surface and to well understood increases in the amount of water vapour that a warmer atmosphere can carry. An increase in rainfall in some regions is in stark contrast to decreases in the frequency in rain in other regions, leading to projections of more flooding but also more droughts in the future.

These projections depend on the physics incorporated within climate models. Careful comparisons with observations are vital in assessing how realistic these projections are and also for confirming current changes….

Heavy tropical thunderstorm approaching, near Koh Samui Island, Thailand, shot by Tatjana8047

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