PNAS Study - Warming May Bring 50-Fold Increase In Frequency Of Extreme Rainstorms By 2100

New research showing how global warming intensifies extreme rainfall at the regional level could help communities better prepare for storms that in the decades ahead threaten to swamp cities and farms. The likelihood of intense storms is rising rapidly in North America, and the study, published Monday in the Proceedings of the National Academy of Sciences, projects big increases in such deluges.

"The longer you have the warming, the stronger the signal gets, and the more you can separate it from random natural variability," said co-author Megan Kirchmeier-Young, a climate scientist with Environment Canada.

Previous research showed that global warming increases the frequency of extreme rainstorms across the Northern Hemisphere, and the new study was able to find that fingerprint for extreme rain in North America. "We're finding that extreme precipitation has increased over North America, and we're finding that's consistent with what the models are showing about the influence of human-caused warming," she said. "We have very high confidence of extreme precipitation in the future."

At the current level of warming caused by greenhouse gases—about 1.8 degrees Fahrenheit above the pre-industrial average—extreme rainstorms that in the past happened once every 20 years will occur every five years, according to the study. If the current rate of warming continues, Earth will heat up 5.4 degrees by 2100. Then, 20, 50 and 100-year extreme rainstorms could happen every 1.5 to 2.5 years, the researchers concluded. "The changes in the return periods really stood out," she said. "That is a key contributor to flash flooding events and it will mean that flash flooding is going to be an increasing concern as well."

EDIT

https://insideclimatenews.org/news/01062020/extreme-rain-study-climate-change