WASHINGTON – Global warming isn't to blame for the recent jump in hurricanes in the Atlantic, concludes a study by a prominent federal scientist whose position has shifted.

Actually, warmer temperatures will reduce the number of hurricanes in the Atlantic and those making landfall, research meteorologist Tom Knutson reported in a study released Sunday.

Previously, Dr. Knutson has raised concerns about the effects of climate change on storms. His new paper has the potential to heat up a simmering debate on the effects of global warming in the Atlantic.

Hurricanes have often symbolized global warming's wrath with many climate change experts linking the rise of hurricanes to global warming.

Another group of hurricane experts, who are more often skeptical about global warming, say there is no link.

What makes this study different is Dr. Knutson, a meteorologist with the National Oceanic and Atmospheric Administration's fluid dynamics lab in Princeton, N.J. He has warned about the harmful effects of climate change and has complained about censorship from the Bush administration.

He said his new computer-based study argues "against the notion that we've already seen a really dramatic increase in Atlantic hurricane activity resulting from greenhouse warming."

The study, published online Sunday in Nature Geoscience, predicts that by century's end the number of Atlantic hurricanes will fall by 18 percent.

However, it's not all good news. His computer model also forecasts that hurricanes and tropical storms will be wetter and fiercer. Rainfall within 30 miles of a hurricane should jump by 37 percent and wind strength should increase by about 2 percent, Dr. Knutson's study says.

MIT hurricane meteorologist Kerry Emanuel called Dr. Knutson's conclusion "demonstrably wrong" based on a model that doesn't look properly at storms.

Kevin Trenberth, a climate scientist, said the model is poor at assessing tropical weather.

Dr. Trenberth, climate analysis chief at the National Center for Atmospheric Research in Boulder, Colo., said it is not just the number of hurricanes "that matter, it is also the intensity, duration and size, and this study falls short on these issues."

Hurricane season starts June 1 in the Atlantic and a Colorado State University forecast predicts about a 50 percent more active than normal storm season this year.

Seth Borenstein,

The Associated Press