Tropical Cyclones Have Slowed over the Last 70 Years


The fierce, swirling storms move 10 percent slower, on average, than they did nearly 70 years ago, a new study finds. Such lingering storms can potentially cause more damage by dumping even more rainfall on land beneath them.

Atmospheric scientist James Kossin examined changes in how quickly tropical cyclones, known as hurricanes in the Atlantic Ocean, moved across the planet from 1949 to 2016. Storms slowed at different rates depending on the region, with the biggest changes seen in the Northern Hemisphere, Kossin reports in the June 7 Nature.

Over that same time period, the average temperature of Earth’s surface rose by about half a degree Celsius. Scientists already predict that average wind speeds will increase in tropical cyclones as ocean waters warm due to global warming (SN: 6/27/15, p. 9). The new study suggests that climate change is also altering how quickly these tropical cyclones travel across land or water.

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