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Eye of the stormThe strongest North Atlantic hurricanes, such as 2005’s Wilma (seen in visible light at left and at right in a false color view that shows differences in the height of clouds), have been getting even stronger in recent years, scientists say.NASA, GSFC, LaRC, JPL, MISR Team

Hurricanes rank among the world’s strongest storms. With fierce winds and pouring rain, these massive squalls can cause major damage to homes, cities and lives.

And these strong storms may be getting even stronger, according to a new study. Over the past three decades, the peak wind speeds for hurricanes in some regions of the world have grown faster, says James P. Kossin, an atmospheric scientist at the University of Wisconsin–Madison.

Kossin and colleagues analyzed storm patterns dating back to the 1980s. For their study, they looked at images of more than 2,000 tropical cyclones worldwide. (Hurricanes are also known as tropical cyclones or typhoons, depending on where on the globe they occur). The images came from satellites orbiting Earth.

The researchers estimated the speed of each cyclone’s fastest winds. To do this, they looked at the temperature of the tallest clouds that formed within each storm. Previous research has shown that colder, higher clouds inside the storm indicate faster winds on the ground.

During the past 30 years, results showed, peak wind speeds for cyclones have picked up the most in the North Atlantic and eastern North Pacific oceans. In 2006, storm winds for the strongest cyclones in both regions blew, on average, 3 meters (10 feet) per second faster than they did in 1981.

Scientists suspect that global warming is responsible for the faster blasts of wind. In both the North Atlantic and eastern North Pacific, temperatures at the water’s surface have risen in recent years. And cyclones feed off of warm seas, especially when there’s a big temperature difference between the surface of the ocean and the upper atmosphere.

Global warming hasn’t increased the number of hurricanes occurring each year. But the storms are getting stronger, say Kossin and other researchers whose studies suggest similar conclusions.

Some experts, however, disagree. One reason is that hurricanes follow cycles that last for decades. By looking at just a short window of time, critics say, the study authors may have read too much into this natural variation.

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