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NASA: Global warming may increase risk for extreme rainfall

A new NASA study says that global warming may increase the risk for extreme rainfall and drought, according to a news release from the space agency. This is the first study to demonstrate how increasing carbon dioxide concentrations could impact the entire range of rainfall types on our planet.

Examination of computer simulations from 14 climate models suggests that wet regions of the world will experience increases in extreme rainfall due to warming resulting from projected increases in carbon dioxide levels. Dry areas and regions with moderate rainfall, however, could be become drier.

According to lead author William Lau of the space agency’s Goddard Space Flight Center, carbon dioxide-induced warming will force the global water cycle to participate in a competition for moisture leading to a global pattern of increased extreme rain, diminished moderate rain, and drawn-out drought in other areas.

NASA’s models project that for every one degree Fahrenheit of carbon dioxide-induced warming, extreme rainfall will increase globally by 3.9 percent and light rain will increase globally by one percent. At the same time, however, moderate rainfall will decrease globally by 1.4 percent, which means that total global rainfall will not change much.

The tropical zones around the equator are projected to experience the most noticeable increase in extreme rainfall.

Though the tropical are projected to see an increase in heavy rainfall, some areas of the world may not experience any rainfall. The space agency’s models also project that for every one degree Fahrenheit of carbon dioxide-induced warming, the number of days with no rain will increase globally by 2.6 percent.

According to Lau, significant changes in moderate rainfall, as well as droughts, can have the biggest impact on society because they take place in areas where a lot of people live. Areas of heavy rainfall, on the other hand, typically occur over the ocean.

The simulations of the 14 climate models started with carbon dioxide concentrations at approximately 280 parts per million and then increased by 1 percent par year, which is consistent with the Intergovernmental Panel on Climate Change’s standard trajectory of the greenhouse gas.

Check out a video of how the model simulations reveal that warming from carbon dioxide will affect the entire range of rainfall types on Earth. The video is provided by NASA’s Goddard Space Flight Center Scientific Visualization Studio.

The study’s findings will be described in detail in the American Geophysical Union journal Geophysical Research Letters.