U.S. could see more torrential downpours, flash floods by 2100

By the end of the century, torrential downpours in some areas of the U.S. could lead to more flash floods, mudslides, and other disasters, according to a new study from the National Center for Atmospheric Research.

The torrential downpours are expected to hit the Southwest, Gulf Coast, and parts of the Atlantic Coast the hardest, researchers said, and could increase rainfall in some areas up to 70 percent. A storm that drops 2 inches of rain today could drop 3.5 inches in the future, the study found.

The additional rain is expected if the Earth continues its current warming trend, because warmer air can hold more water, the research team said. Increases in intense downpours have already been recorded across the U.S., they pointed out.

Average global temperatures have been on the rise since about 1880, except for a dip in the 1910s.

The NCAR researchers built a new dataset using current trends to create a new computer climate model that could simulate intense downpours. They then used the dataset to examine changes in storms and downpours over recent years, and to predict how these changes might affect future storm intensity.

They used predictions of a climate that is 9 degrees Fahrenheit warmer in 2100, which some scientists warn may be the case if greenhouse gas emissions continue at the current rate.

The team found that summertime storms could increase all over the country, but areas like Nebraska, North Dakota, and Iowa are likely to see less of an effect than the Gulf Coast or Southwest. The latter regions could see storms that are 200 to 400 percent more intense in the summer months, the researchers said.

Storms could occur in hotter weather than they do normally, too, the scientists found.

The next step is determining how rain-fueled extreme weather events might affect infrastructure in those areas, and working to make changes before disaster strikes, said Anjuli Bamzai, director of the National Science Foundation Directorate of Geosciences, which co-funded the research.

The study was published in the journal Nature Climate Change. Additional funding came from the Research Partnership to Secure Energy for America.

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By Olivia Harvey, Earth.com Staff Writer