Global Warming may Create Violent Stroms

by Jayashree on Aug 31 2007 4:28 PM

Global Warming may Create Violent Stroms
Global warming could make storms more severe and violent, according to a new climate model developed by scientists at NASA’s Goddard Institute for Space Studies.
Global computer models represent weather and climate over regions several hundred miles wide. The models do not directly simulate thunderstorms and lightning. Instead, they evaluate when conditions are conducive to the outbreak of storms of varying strengths.

While previous climate models have shown that heavy rainstorms will be more common in a warmer climate, they have not attempted to simulate the strength of updrafts in these storms.

The new model is the first to successfully simulate the observed difference in strength between land and ocean storms and estimate how the strength will change in a warming climate, including “severe thunderstorms” that also occur with significant wind shear and produce damaging winds at the ground.

Scientists say this information can be derived from the temperatures and humidity predicted by a climate computer model.

The model predicts that in a warmer climate, stronger and more severe storms can be expected, but with fewer storms overall.

The scientists first tested the model against current climate conditions, representing major known global storm features including the prevalence of lightning over tropical continents such as Africa, and to a lesser extent, the Amazon Basin, and the near absence of lightning in oceanic storms.

The model was then applied to a hypothetical future climate with double the current carbon dioxide level and a surface that was an average of 5 degrees Fahrenheit warmer than the current climate.

The researchers found that continents warmed more than oceans and that the altitude at which lightning forms rose to a level where the storms were usually more vigorous.

Together, these effects combined to cause more of the continental storms that formed in the warmer climate to resemble the strongest storms that Earth currently experiences, the scientists wrote in their study in the August 17 issue in the American Geophysical Union’s Geophysical Research Letters.

Lead author Tony Del Genio said their model suggested, that in a warmer climate, stronger and more severe storms could be expected, but with fewer storms overall.

“These findings may seem to imply that fewer storms in the future will be good news for disastrous western US wildfires. But drier conditions near the ground combined with higher lightning flash rates per storm may end up intensifying wildfire damage instead ,” said Del Genio.


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