Their research is based on an analysis of 10 global climate computer simulations, from the U.S. National Center for Atmospheric Research, the U.S. National Oceanic and Atmospheric Administration's Geophysical Fluid Dynamics Laboratory, and from Australia, Britain, France, Germany and Japan. (The study is published this week in the PNAS online edition.)
The majority of the computer models calls for a substantial decrease in tropical rainfall to occur by 2054, or sooner under some of the models, said J. David Neelin, UCLA professor of atmospheric and oceanic sciences, a member of UCLA's Institute of Geophysics and Planetary Physics, and lead author of the study. By the end of this century, the models call for a decrease in summer rainfall of 20 percent or more in parts of the Caribbean and Central America, Neelin said. The winter change in rainfall in this region is not dramatic, added Neelin, who noted that summer and winter rains occur by very different climate phenomena. If the models prove correct, the decreased rainfall would be a consequence of human-induced global warming, he said.
"The regions in the tropics that get a lot of summer precipitation are going to get more, and the regions that get very little precipitation will get even less, if the models are correct," Neelin said. "Certain regions in between will get shifted from a moderate amount of precipitation to a low amount. The bigger the temperature rise, the larger the change in precipitation."
Neelin cautioned, however, that precipitation changes due to global warming have been more difficult to detect and attribute to global warming than changes in temperature.
"Precipitation change is much more difficult than tem
Source:University of California - Los Angeles