Hurricanes are slowing down, wreaking havoc on coastal communities


Overall, the study looked at tropical cyclones, which is an umbrella term that includes tropical storms, hurricanes and typhoons. While this sounds like good news, it isn't: It's not that hurricanes' wind speeds are diminishing, but instead how fast the entire storm moves, a new study reports.

The unusually slow-moving Hurricane Harvey was a recent example. But when Atlantic storms hit land - like Harvey - the study said the slowdown is a significant 20 percent.

A scientist at the National Oceanic and Atmospheric Administration has found a link between global warming and the speed of hurricanes.

Kossin's work was based on details of nearly 70 years' worth of storms, but he made no attempt to determine what was causing the slowdown.

Kossin told Nature that a 10% slow-down in storm speed corresponds to a 10% increase in rainfall when a hurricane makes landfall.

Kossin argues that the slow-down is caused by global warming, which is both increasing rainfall and decreasing wind currents. Instead, it means the tracks of the storms have slowed, allowing them to hover in one location for longer periods of time.

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They say while global warming is projected to increase the severity of the strongest tropical cyclones, warming may bring other more serious effects such as the general weakening of summertime tropical atmospheric circulation.

Although commending the study for its findings, she said it is not without its limitations.

Previous research has shown that a warmer climate can hold more water moisture, so when it rains, it rains more.

He said beyond the changes in regularity and intensity of cyclones, their very "behaviour" was being affected by climate change.

By plugging storm data into computer models representing a future with temperatures that are up to five degrees warmer, they found that these cyclones moved 9 percent slower and were far, far wetter.

"What we're seeing nearly certainly reflects both natural and human-caused changes", Kossin said.