Is the rash of powerful Atlantic storms in recent years a symptom of global warming?
Although most mainstream hurricane scientists are skeptical of any connection between global warming and heightened storm activity, the growing intensity of hurricanes and the frequency of large storms are leading some to rethink long-held views.
Most hurricane scientists maintain that linking global warming to more-frequent severe storms, such as Hurricane Katrina, is premature, at best.
Though warmer sea-surface temperatures caused by climate change theoretically could boost the frequency and potency of hurricanes, scientists say the 150-year record of Atlantic storms shows ample precedent for recent events.
But a paper published last month in the journal Nature by meteorologist Kerry Emanuel of the Massachusetts Institute of Technology is part of an emerging body of research challenging the prevailing view.
It concluded that the destructive power of hurricanes had increased 50% over the last half a century, and that a rise in surface temperatures linked to global warming was at least partly responsible.
"I was one of those skeptics myself -- a year ago," Emanuel said Monday.
But after examining data on hurricanes in the Atlantic and typhoons in the Pacific, he said, "I was startled to see this upward trend" in duration and top wind speeds.
"People are beginning to seriously wonder whether there is a [global warming] signal there. I think you are going to see a lot more of a focus on this in coming years."
Hurricane activity in the Atlantic has been higher than normal in nine of the last 11 years, said the National Oceanic and Atmospheric Administration.
This month, the agency raised its already-high hurricane forecast for this year to 18 to 21 tropical storms, including as many as 11 that would become hurricanes and five to seven that would reach major-hurricane status. That could make 2005 one of the most violent hurricane seasons ever recorded. A typical storm year in the Atlantic results in six hurricanes.
But the agency believes that the increase in hurricanes is most likely the result of a confluence of cyclical ocean and atmospheric conditions that tend to produce heightened tropical storms every 20 to 30 years. If global warming is playing any role in the hurricanes, it is a minor one, the federal agency maintains.
