Friday, October 21, 2005

After briefly becoming the most intense Atlantic storm ever observed, with top sustained winds of 175 miles an hour on Wednesday morning, Hurricane Wilma’s winds had eased to 145 m.p.h. on October 20, 2005, according to the National Hurricane Center Web site. A reconnaissance aircraft found the air at Hurricane Wilma’s eye on the morning of October 19 to be just 12.8 pounds per square inch, the lowest pressure ever measured in an Atlantic hurricane. The previous low was Hurricane Gilbert in 1988, at 12.9 pounds per square inch. Air pressure at sea level is usually 14.7 pounds per square inch.

With Hurricanes Katrina and Rita hitting the United States with devastating force, Wilma was the 21st tropical storm to form in the Atlantic this year, tying the 1933 record for the busiest season since hurricane counting started in 1851. But the hurricane season continues for an additional six weeks, ending Nov. 30.

However, this season does not rank as the most intense by some measures. An index that tracks the total energy of the storms - taking into account how long the storms last - finds that this year the total energy is about twice the average. But in 1950, the index, called the accumulated cyclone energy, was 2.7 times the average.

In recent months, two studies in the journal Science and one in Nature have found that hurricanes are growing fiercer. Although other research is also drawing the same conclusion, many critics say any attempt to link hurricanes with climate change is just another sign of global-warming "hysteria."

It’s hard to find anything in the peer-reviewed scientific literature that says something opposite to what these three papers have found. Yet, hurricane expert William Gray of Colorado State University recently told Discover magazine that he sees no link between global warming and hurricanes. He also made the same comments on television and during congressional testimony. When questioned by senators, Dr. Gray was unable to cite peer-reviewed studies to back up his claims.

During a program on MSNBC in late September, conservative talk-show host Tucker Carlson addressed the debate that climate change is creating more powerful hurricanes by saying, "[s]ome people will always interpret that for political reasons, of course."

"So many people have a vested interest in this global-warming thing—all these big labs and research and stuff," said Dr. Gray in the Discover interview. "The idea is to frighten the public, to get money to study it more."

Max Mayfield, the director of the National Hurricane Center, has given similar congressional testimony in recent weeks. During recent Senate hearings, Senator James Inhofe (R-OK) invited science-fiction writer and noted global-warming critic Michael Crichton to speak about climate change.

Dr. Judith Curry, the chair of the school of earth and atmospheric sciences at Georgia Tech, is the coauthor of one of the Science papers on hurricanes and climate change. She serves on a variety of panels related to climate, including the National Academies’ space studies board and the National Oceanic and Atmospheric Administration’s climate-research working group. Dr. Curry noted that the American public doesn’t read scientific journals – instead, they listen to the media, and the media likes a good debate. So the media "trot out this small minority of people to present their contrarian views. And they are given just as much legitimacy as scientists with strong credentials and who publish in the peer-reviewed literature. The media gives equal weight to both sides of this. So the American public gets confused."

Referring to her paper, Dr. Curry said "People have accused us of linking global warming with Katrina. We didn’t even use the expression 'global warming' in the paper. We talked about an increase in global tropical sea surface temperature."

"What we looked at was the global data set that is available from 1970 through 2004, and it’s a satellite-based data set, so we’re able to look at every single tropical storm and hurricane. And what we looked at was the frequency, intensity, and number of hurricane days for each ocean basin where they have hurricanes. We looked concurrently at the sea surface temperature over that same period for each ocean basin. What we find—again, the increase of tropical sea surface temperature in these regions is well known—is that there was an increase in the frequency, almost a doubling, of the most intense hurricanes—the category 4s and 5s. And a similar increase in the number of hurricane days."

On October 25, 2005 the American Meteorological Society will host a briefing on Capitol Hill about hurricanes. Along with Dr. Curry, Kerry Emanuel of the Massachussetts Institute of Technology and Kevin Trenberth of the National Center for Atmospheric Research will present their published findings on hurricanes and global warming.

1 comment:

GreenSmile said...

Much more thorough post on this topic than my diatribes. really makes you wonder how some people are so good at missing the distinction between a measurement and an allegation.