The debate is over?

If warming does have an effect, it amounts to meaningless "noise," Landsea said at the conference.

FROM- Sarasota Herald-Tribune
Scientist says climate change isn't fueling hurricanes


FORT LAUDERDALE - Earth is warming, but not fueling the increase in Atlantic hurricanes this decade, according to new research by a top federal scientist.

Hurricane specialist Chris Landsea, with the National Hurricane Center in Miami, disputes theories that global warming has caused more hurricanes, in a study to be published soon in The Journal of Climate.

Since the mid-1990s, the average number of hurricanes per year has been almost double what it was during the few decades before, but about on par with hurricane activity in the early 20th century, Landsea's research shows.

"It's busy, yes, but not anything we haven't seen before," Landsea said at last week's Governor's Hurricane Conference.

Other scientists disagree, disputing his conclusions and finding more significance in research that shows warming increases hurricane intensity.

Landsea scrutinized the hurricane center's storm data and corrected for technological advances in hurricane detection and tracking. He concluded that hurricane seasons of the past rivaled today's activity, suggesting the influence of a periodic climate cycle in the Atlantic, not global warming, is behind the current spike in storms.

A hot topic

Global warming and hurricanes became a hot topic of debate after the record-setting 2004 and 2005 hurricane seasons. The number and ferocity of storms, including Hurricane Katrina, which swiped Florida before devastating New Orleans and the northern Gulf of Mexico coast in 2005, increased speculation that global warming played a role.

Landsea's new study, currently under review by other scientists, stemmed from his objection to studies in 2006 and 2007 linking the increased number of recorded hurricanes with a rise in global temperatures.

"I did not agree with the studies because I thought their assumption that all the storms were in the database was faulty," Landsea said.

Scientific debate over the cause of hurricane activity is more than academic. Experts' ability to understand the forces behind storm formation affects hurricane forecasts, which in turn affect public safety, disaster preparedness and even insurance costs.

The criticism

Landsea's study garnered praise from meteorologists after he presented it at last week's hurricane conference, but it is sparking controversy among hurricane researchers.
More...
One of his biggest critics is Michael Mann, professor of meteorology at Pennsylvania State University and lead author of a 2007 study that linked warming with an increase in hurricanes.

Mann disputed Landsea's research, saying that his technology argument ignores the chance that a single storm could have been counted twice before satellite records could show the exact track. He expressed doubt that the study would pass muster to be published.

Kerry Emanuel, a leading hurricane researcher and professor of atmospheric science at Massachusetts Institute of Technology, said Landsea's work is scientifically robust, but not as important as looking at whether warming causes hurricanes to gain strength.

"I don't think the number of storms is a terribly interesting thing," Emanuel said, emphasizing Atlantic storms now rarely exceed Category 2 strength, but that the majority of damage-inflicting storms are Category 3 or higher. "We're pretty confident that intensity increases with global temperature. There are arguments about the amount."

Data, and lack thereof

The National Hurricane Center's database goes back to the 1880s. On its face, the information appears to show an obvious upward trend in the number of hurricanes. But with satellites, airplane reconnaissance, data-collecting buoys and unprecedented teams of scientists, no tropical storm goes unnoticed today.

In the early 1900s, only storms that threatened land or ships at sea were recorded.

In their publications, the scientists who demonstrated an increase in hurricane activity maintained that the number of missed storms would be too insignificant to alter the strong upward trend.

But Landsea's research showed that just taking out all the minor tropical storms -- those that lasted less than 36 hours with no threat to land -- nearly erased the upward trend.

Furthermore, he used research by scientists at Princeton to guess at how many storms were missed in the past. Adding those storms weakened the trend to zero, instead showing spikes in hurricane activity during periods when sea surface temperatures in the Atlantic averaged about 1 degree above normal, a phenomenon that is thought to shift every 30 to 50 years.

Several meteorologists and weather forecasters say the trend, called Atlantic Multi-decadal Oscillation, explains why there are more hurricanes now and why the nation saw many more devastating hurricanes in the mid-1920s through the 1950s, compared to the 1960s through the early 1990s.

But scientists also debate whether Atlantic Multi-decadal Oscillation even exists.

No single weather trend influences hurricane activity. The interactions between the sun, sea, atmosphere, moon and the rotation of the Earth creates uncountable variables in the weather, making it difficult to predict and understand.

Landsea and most other hurricane scientists do not dispute climate change or some human contributions to it. Landsea simply challenges the thinking that warming substantially affects hurricane activity.

If warming does have an effect, it amounts to meaningless "noise," Landsea said at the conference.