Science

Study says tropical cyclones slowing

Study says tropical cyclones slowing

"We've kind of hypothesized that this type of behavior may happen, this slowing down of the forward speed of the cyclones", said Colin Zarzycki, a climate scientist at the National Center for Atmospheric Research who has reviewed at Kossin's study.

A fast storm can distribute its water across a wider surface area, decreasing the chance of extreme flooding. Adding last year's storms would have made the slowdown a bit more prominent, he said.

James Kossin's research showed that over the past 68 years, cyclones have slowed by 10 percent globally as the planet warms.

In addition to slower atmospheric circulations possibly causing the storms to move slower, the amount of rainfall that the storms are able to dump is increasing as global temperatures climb.

To understand the relationship between climate change and hurricane speeds, Kossin analyzed the paths of 7,585 tropical cyclones from 1949 to 2016.

The U.S. National Hurricane Center said Tropical Storm Aletta was centered about 425 miles (680 kilometers) southwest of Manzanillo, Mexico, late Wednesday.

"Tropical cyclones are just carried along by the wind, so it makes sense", Kossin says.




Kossin said the findings were of great importance to society.

"The storms will stay in your neighbourhoods longer", he said.

Gutmann and Kossin took entirely different approaches-one looking at historical data; the other using modeling to see how storms would behave under predicted warming scenarios.

Kossin would actually agree on that point.

But Kossin, in his paper, writes that he wouldn't expect big changes in his results due to different means of measurement, since "estimates of tropical-cyclone position should be comparatively insensitive to such changes".

These lingering tropical cyclones - including hurricanes and typhoons - are increasing the risk of deadly flooding worldwide, scientists have warned. "And when you start getting more and more lines of evidence that all point in the same direction, you get more confident in the answers".