The United States faces the most destructive hurricanes more than three times as often as it did a century ago, according to a new study in the Proceedings of the National Academy of Sciences that blames the shift “unequivocally” on climate change.
“A new way of calculating the destruction, compensating for the societal change in wealth, unequivocally shows a climatic increase in the frequency of the most destructive hurricanes that routinely raise havoc on the North American south and east coast,” the University of Copenhagen said in a release. In contrast to past research, the new study adjusts for increases in wealth that previously made it more controversial to attribute the rising economic cost of hurricanes to a warming climate.
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“Experts generally measure a hurricane’s destruction by adding up how much damage it did to people and cities,” The Associated Press explains. “That can overlook storms that are powerful, but that hit only sparsely populated areas.” The Copenhagen team “came up with a new measurement that looked at just how big and strong the hurricane was, not how much money it cost. They call it Area of Total Destruction.”
And by that metric, “it’s the most damaging ones that are increasing the most,” said lead author Aslak Grinsted, a climate scientist at Copenhagen’s Niels Bohr Institute. “This is exactly what you would expect with climate models.”
“Looking at 247 hurricanes that hit the U.S. since 1900, the researchers found the top 10% of hurricanes, those with an area of total devastation of more than 467 square miles (1,209 square kilometres), are happening 3.3 times more frequently,” AP adds. “Eight of the 20 storms with the highest area of total destruction since 1900 have happened in the last 16 years, a much larger chunk than would randomly occur.”
“In this study, we develop a record of normalized damage since 1900 based on an equivalent area of total destruction,” the research team writes in its published abstract. “Our data reveal an emergent positive trend in damage, which we attribute to a detectable change in extreme storms due to global warming. Moreover, we show that this increasing trend in damage can also be exposed in existing normalized damage records by looking at the frequency of the largest damage events.”
The researchers singled out two U.S. storms for their areas of destruction: Hurricane Harvey, which hit a 4,570-square-mile swath of Texas in 2017, and Hurricane Katrina, which drowned New Orleans and devastated 2,942 square miles of the U.S. Gulf Coast in 2005.
U.S. National Oceanic and Atmospheric Administration hurricane scientist Jim Kossin, who was not involved with the research, told AP the results are “consistent with expected changes in the proportion of the strongest hurricanes, and [are] also consistent with the increased frequency of very slow-moving storms that make landfall in the U.S.” Colorado State hurricane specialist Phil Klotzbach disagreed, stating that he’d seen no change in the most severe storms based on their barometric pressure.
