A new NASA study shows for the first time how rising levels of carbon dioxide associated with global warming can lead to both extreme rainfall and drought across Earth.

The study, based on computer simulations from 14 climate models, indicates that the world's wettest regions, such as the equatorial Pacific Ocean and Asian monsoon regions, will see increases in heavy rainfall because of warming resulting from projected increases in carbon dioxide levels. Arid land areas outside the tropics and many regions with moderate rainfall could become drier, according to the NASA report.

"In response to carbon dioxide-induced warming, the global water cycle undergoes a gigantic competition for moisture resulting in a global pattern of increased heavy rain, decreased moderate rain, and prolonged droughts in certain regions," said William Lau of NASA's Goddard Space Flight Center in Greenbelt, Md., and lead author of the study.

For every 1 degree Fahrenheit of carbon dioxide-induced warming, heavy rainfall will increase globally by 3.9 percent and light rain will increase globally by 1 percent, the climate models predict.

But total global rainfall is not predicted to change much because moderate rainfall will decrease globally by 1.4 percent, NASA reports.

The tropical zones around the equator, particularly in the Pacific Ocean and Asian monsoon regions, are predicted to see the most increased rainfall.

The models also projected for every degree Fahrenheit of warming, the length of periods with no rain will increase globally by 2.6 percent, which could potentially impact a vast range of territories in the Northern Hemisphere.

"Large changes in moderate rainfall, as well as prolonged no-rain events, can have the most impact on society because they occur in regions where most people live," Lau said. "Ironically, the regions of heavier rainfall, except for the Asian monsoon, may have the smallest societal impact because they usually occur over the ocean."

Though Lau said the models were not reliable for predicting how much rain will fall in any one location, when looked at as a whole the models paint a clear picture.

"But if we look at the entire spectrum of rainfall types we see all the models agree in a very fundamental way -- projecting more heavy rain, less moderate rain events, and prolonged droughts," Lau said.