August 18, 2009

Scientists forecast heavier rainstorms

A U.S. study suggests we can expect heavier rainstorms in the future thanks to the impact global climate change will have on precipitation patterns.

But Massachusetts Institute of Technology and Caltech scientists say the increase in rainfall will not be uniformly spread around the world.

Overall, previous studies have shown average annual rainfall will increase in both the deep tropics and over Earth's temperate zones, but will decrease in the subtropics.

The new study focused on how the frequency and magnitude of extreme precipitation events will be affected.

MIT Assistant Professor Paul O'Gorman and Caltech Professor Tapio Schneider used model simulations that suggest precipitation in extreme events will go up by about 6 percent for every one degree Celsius increase in temperature.

Separate projections published earlier this year by MIT's Joint Program on the Science and Policy of Global Change indicate that without rapid and massive policy changes, there is a median probability of global surface warming of 5.2 degrees Celsius by 2100, with a 90 percent probability range of 3.5 to 7.4 degrees.

The research is detailed in the early online edition of the Proceedings of the National Academy of Sciences.