Hurricane rains 15 percent worse due to climate change, scientists find

by Sebastien Malo | @SebastienMalo | Thomson Reuters Foundation
Thursday, 14 December 2017 19:35 GMT

Residents wade through flood waters from Tropical Storm Harvey in Beaumont Place, Houston, Texas, U.S., August 28, 2017. REUTERS/Jonathan Bachman/File photo

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"This analysis makes clear that extreme rainfall events along the Gulf Coast are on the rise"

By Sebastien Malo

NEW YORK, Dec 14 (Thomson Reuters Foundation) - The rains of Hurricane Harvey that devastated the U.S. Gulf Coast this summer were 15 percent higher due to climate change, which is making such catastrophic storms three times more common, new research shows.

The storm dropped more than 50 inches (127 cm) in some areas and caused disastrous flooding in Texas and Louisiana, said World Weather Attribution, a coalition of U.S., European and Australian scientists.

Experts, including United Nations meteorologists, had established that the deluge was linked to climate change, given the scientific consensus that global warming increases rainfall because warmer air holds more moisture.

But the study, published this week in Environmental Research Letters, a scientific journal, breaks new ground by measuring the portion of rainfall that can be pinned to global warming.

It said the rainfall was 15 percent higher than it would have been without climate change, and such historic rains are three times more common along the Gulf of Mexico coast than they were a century ago.

"This analysis makes clear that extreme rainfall events along the Gulf Coast are on the rise," the scientists wrote.

Harvey made landfall in Texas on August 25 and lingered over the coast for several days.

The strongest hurricane to hit the state in more than 50 years, it was blamed for more than 80 deaths. Damage in Houston, the country's fourth biggest city, has been estimated at $198 billion.

The likelihood of another storm on the same scale is about once in 100 years, compared with once in 160 years without global warming, Geert Jan van Oldenborgh, a senior researcher at the Royal Netherlands Meteorological Institute and the study's lead author, told the Thomson Reuters Foundation.

To measure the impact of climate change, the researchers used a technique known as event attribution, which has become more effective due to advances in computing power.

The process involves a network of computers comparing weather scenarios with and without climate change, using an array of models with historic climate data.

The study shows the need to plan reconstruction with more extreme rains and flooding in mind, said study co-author Antonia Sebastian, a postdoctoral researcher at Rice University in Houston.

"Our hazards are changing over time," she said in a statement. "We should be considering those changes in the design of our infrastructure."

An agreement to tackle climate change by limiting the use of fossil fuels was reached by more than 190 countries in Paris in 2015.

President Donald Trump, who has said he thinks climate change is a hoax, has pulled the United States out of the Paris agreement, and his administration has weakened environmental protections.

(Reporting by Sebastien Malo @sebastienmalo, Editing by Ellen Wulfhorst. Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's rights, trafficking, property rights, climate change and resilience. Visit http://news.trust.org)

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