Climate simulations project wetter, windier hurricanes

New supercomputer simulations by climate scientists at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) have shown that climate change intensified the amount of rainfall in recent hurricanes such as Katrina, Irma, and Maria by 5 to 10 percent. They further found that if those hurricanes were to occur in a future world that is warmer than present, those storms would have even more rainfall and stronger winds.

The computer simulation on the left shows the rainfall intensity of Hurricane Maria under actual conditions. The other images show how much anthropogenic warming already has impacted rainfall intensity (middle) and its projected impact in a warmer climate (RCP8.5). Green areas indicate heavier rain while brown areas mean less rain.

In addition to the pre-industrial scenario, Patricola and Wehner also simulated the tropical cyclones occurring in three future climate scenarios, known as RCP4.5, RCP6.0, and RCP8.5, each representing increasing levels of greenhouse gas emissions and global warming. Since the beginning of the 20th century, average global surface temperatures have risen about 1 degree Celsius; in RCP8.5, the most extreme scenario, temperatures are expected to rise another 3 to 4 degrees.

Several studies, including one from Berkeley Lab published last year in Geophysical Research Letters, found that climate change increased the rainfall from Hurricane Harvey, based on statistical analysis of observations. "When both approaches agree, we can have more confidence in the results," she said. "Scientists are coming to a consensus that global warming will lead to increases in rainfall from tropical cyclones. One of the remaining uncertainties is how much."

https://www.sciencedaily.com/releases/2018/11/181114132019.htm