Scientists have known for years that tropical cyclones are slowing down as they move across Earth’s oceans. But new research presents an alarming update: Many are suddenly losing speed within about 100 miles of a vulnerable coastline, where slow-moving storms can dump catastrophic volumes of rain.
Even more worrisome, scientists say, is that these events often are happening in tandem with rapid intensification events. The result is an increase in large, slow, dangerous hurricanes churning toward human communities.
A study published last month in the Journal of Climate finds that rapid slowdown events became dramatically more frequent between 1982 and 2023, increasing fourfold within 250 miles of coastlines around the world. The research team, representing multiple research institutes in China, defined rapid slowdowns as a decrease of around 5 miles per hour within a six-hour period.
Previously rare, the average annual number of rapid slowdowns grew from less than five in the 1980s to about 20 by the year 2023. The most significant increases occurred within about 120 miles of a coastline, the study also found.
