Climate change added at least 10% more rainfall to Hurricane Ian, a study prepared shortly after the storm’s arrival.
Thursday’s study, which was not peer-reviewed, compared peak rainfall rates during an actual storm with about 20 different computer scenarios of a model with features of Hurricane Ian’s landfall. Sunshine State in a world without human-caused climate change.
“The storm was actually 10 percent wetter than a hurricane could have been,” said Lawrence Berkeley National Laboratory climate scientist Michael Wehner, a co-author of the study.
Forecasters predict Ian will drop up to 61 centimeters of rain in parts of Florida by the time it stops.
Wehner and Kevin Reed, an atmospheric scientist at Stony Brook University, published a study in the journal Nature Communications earlier this year that looked at 2020 hurricanes and found over a three-hour period of rain At most, they are 10% wetter than a world without greenhouse gases that trap heat. Wehner and Reed applied the same scientifically accepted attribution technique to Hurricane Ian.
An age-old law of physics is that for every additional degree of Celsius (1.8 degrees Fahrenheit) in warmth, the air in the atmosphere can contain 7% more water. This week, the Gulf of Mexico is 0.8 degrees warmer than usual, which means about 5% more rainfall. The reality turned out to be even worse. Flash study shows the storm doubles – 10% more rainfall.
Ten percent doesn’t sound like a lot, but 10 percent of 20 inches (50 centimeters) is two inches (five centimeters), which is a lot of rain, especially over 20 inches that have fallen, Reed said.
Other studies have seen similar feedback mechanisms of stronger storms in warmer weather, said Princeton University atmospheric scientist Gabriel Vecchi, who was not involved in the study.
In general, a warmer world would make hurricanes less rainy, says MIT hurricane researcher Kerry Emanuel. But he said he was uncomfortable drawing conclusions about individual storms.
“This heavy rain business is something we expect to see due to climate change,” he said. “We’ll see more storms like Ian.”
Princeton’s Vecchi said in an email that if the world is to recover from a disaster “we need to plan for wetter storms in the future, as global warming is not going away.”
