Changing Pace

Big tropical storms are slowing down in a hurry. If that sounds a little contradictory, think of it this way: More storms are slamming on the brakes as they get close to land. As a result, they spend more time along the coast before they move inland, making them even more dangerous.

Researchers poked through records of tropical cyclones across the globe from 1982 to 2023. They were looking for “rapid slowdown” events—storms that slowed their forward motion by a significant amount in just a few hours. They found that the rate of such events over the open ocean hadn’t changed much over that time. But for storms within about 250 miles of shore, the rate had gone way up.

For storms that slowed by about five miles per hour over a period of six hours or less, the rate quadrupled—from fewer than five events per year to about 20. And there was a link between storms that slowed down quickly and those that strengthened quickly. The combination creates longer-lasting storm surges, winds, and rains—a killer combination.

The number of these events was especially high in the western Pacific Ocean and the southern Indian Ocean. The number was lower in North America.

The researchers said that part of the change could be caused by a natural climate cycle in the Pacific. But most of it likely is powered by human-caused climate change. It’s heating the oceans and altering circulation patterns in both air and sea—making some big storms slow down in a hurry.

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