Hurricane frequency, climate change linked

BOULDER, Colo., July 30 (UPI) -- U.S. scientists say about twice as many Atlantic hurricanes now form each year than did a century ago in a change possibly linked with global warming.

The new statistical analysis of hurricanes and tropical storms in the north Atlantic was conducted by Greg Holland at the National Center for Atmospheric Research and Peter Webster of the Georgia Institute of Technology. Their study concludes warmer sea surface temperatures and altered wind patterns associated with climate change are fueling much of the increase.

The analysis identifies three periods since 1900, separated by sharp transitions, during which the average number of hurricanes and tropical storms increased dramatically and then remained elevated and relatively steady.

The first period, between 1900 and 1930, saw an average of six major Atlantic storms annually, of which four were hurricanes and two were tropical storms. From 1930 to 1940, the annual average increased to 10, consisting of five hurricanes and five tropical storms. During the final study period of 1995 to 2005, the average reached 15, of which eight were hurricanes and seven were tropical storms.

The study appears in the online issue of Philosophical Transactions of the Royal Society of London.