Tropical Storms Shift Toward Poles

http://news.yahoo.com/hurricanes-move-tropical-storms-shift-toward-poles-171756771.html

Hurricanes on the Move! Tropical Storms Shift Toward Poles

By By Becky Oskin May 13, 2014

Hurricanes and typhoons are migrating from the tropics toward the North and South poles, a new study finds.

In the past 30 years, the total number of storms has remained about the same in the tropics, said lead study author Jim Kossin, a climate scientist with the National Oceanic and Atmospheric Administration's National Climatic Data Center.

What has changed, however, is the number of successful storm births.

The new study found that tropical storms don't peak in the tropics as often as they did 30 years ago. Instead, more and more storms are reaching their maximum strength at higher latitudes, according to the report, published today (May 14) in the journal Nature. [Hurricanes from Above: See Nature's Biggest Storms]

"The tropics are becoming less hospitable for tropical cyclones, and the higher latitudes are becoming less hostile," Kossin told Live Science's Our Amazing Planet.

Tropical cyclones (the broad name for hurricanes, typhoons and tropical storms)

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The tropics have widened by about a degree in latitude each decade since 1979, according to separate studies by other research groups.

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The expansion of the tropics has been linked to global warming and ozone loss. But scientists still hotly debate the impact of global warming on hurricanes. Storms could become more or less frequent, more intense or a combination of these changes, researchers say.

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The poleward trek doesn't necessarily mean that ferocious storms will be hitting the Atlantic coastline more often. As climate changes, fluctuating wind patterns could cause tropical storms to move toward or away from coastlines, for instance. And the study didn't examine landfall, where storms do the most damage. [Most of the Atlantic hurricanes that headed towards the U.S. in last few years ended up veering away before they reached the U.S., due to such weather patterns. Some of them ended up attacking England and Europe.]

Another confounding factor: The Atlantic Ocean storm nursery did not move north in the past 30 years, the researchers reported. Kossin said he suspects that regional effects in the Atlantic, such as aerosol pollution (tiny airborne particles), could be offsetting the overall tropical widening.

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But some oceans saw a greater change than others. The biggest moves occurred in the Pacific Ocean and South Indian Ocean, but the peak intensity of Atlantic hurricanes and storms in the North Indian Ocean showed almost no change.

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