Studies: Climate change boosted Hurricane Harvey’s deluge
NEW ORLEANS — Hurricane Harvey’s historic deluge in Texas showed clear signs of human-caused climate change, with rainfall at least 15 percent heavier and the likelihood of such a calamity tripled, according to two independent studies published Wednesday. The new findings are part of a surge of research suggesting that communities need to revisit their vulnerability to extreme weather in a warming world.
“Climate change made this event more likely and heavier,” said Karin van der Wiel, a researcher at the Royal Netherlands Meteorological Institute who cowrote one of the papers and is among 25,000 people attending the fall meeting of the American Geophysical Union here.
Hurricane Harvey hit the Texas coast near Corpus Christi on Aug. 25 after it intensified rapidly in the Gulf of Mexico. The storm then stalled and dropped record rain for the better part of a week on Southeast Texas before drifting north and dissipating. The storm flooded Houston and much of the region and was one of several hurricanes that impacted the United States during a volatile 2017 season, including Hurricane Irma in Florida and Hurricane Maria in Puerto Rico.
Van der Wiel and her colleagues concluded that a deluge such as Harvey would have occurred in the region once every 2,400 years in the pre-warming period but that it is now a 1-in-800 year event — and is becoming more likely. Her research found that warming likely increased the intensity of the storm’s precipitation by approximately 15 percent.
The second study, from researchers based at the Lawrence Berkeley National Laboratory, said Harvey’s precipitation was likely boosted by at least 19 percent. And that’s just the lower bound; the team’s best estimate, which acknowledges a great deal of uncertainty, is a 38 percent increase. The report found the likelihood of a Harveylike event had probably increased tenfold but at the very least had tripled.
“Thirty-eight percent seems pretty big,” Columbia University research professor Suzana Camargo, an expert on extreme weather, said when she looked over a poster outlining the research of Michael Wehner, senior staff scientist at the national laboratory in Berkeley. She said this kind of research points to the inadequacy of today’s flood maps, which need updating as the climate changes: “They have not been improving the maps as they should. They’re treating that as static.”
The Dutch and Berkeley research teams worked independently and used different methods — for example, examining different geographical areas, different time periods during the week that Harvey struck Texas, and framing their findings with different standards of certainty.