Hurricanes feed on warm water, and a study released Monday shows a link between warmer ocean temperatures and human use of fossil fuels, challenging skeptics who blame them on natural climate cycles.
WASHINGTON Hurricanes feed on warm water, and a study released Monday shows a link between warmer ocean temperatures and human use of fossil fuels, challenging skeptics who blame them on natural climate cycles.
"Our paper suggests that it's human-induced burning of fossil fuels that have altered the levels of greenhouse gases in the atmosphere that have led to this warming in regions where Atlantic and Pacific hurricanes form," said Benjamin Santer, a climate scientist and co-author of an article in this week's Proceedings of the National Academy of Sciences.
Santer and his colleagues focused on these hurricane zones, and used computer models to figure out what the world would have been like if the Industrial Revolution had never happened.
That way, they could compare what Earth is like now with what all available computer models -- 22 of them -- indicate it would have been like if humans had never burned fossil fuels, Santer said in a telephone interview.
The question of whether humans cause global warming is a subject of heated debate among scientists, but there is general agreement that warm sea surface temperatures in hurricane zones contribute to hurricane intensity.
Santer and the other researchers found only a combination of human-made and natural climate influences could account for the rise in sea surface temperatures by about 1 degree F over the last century.
The scientists estimated an 84 percent chance that at least two-thirds of the sea surface temperature increase were due to human activity.
They started work on the project soon after Hurricane Katrina slammed into the U.S. Gulf Coast a year ago, said Santer, who is based at the Lawrence Livermore National Laboratory in California.
The 22 computer models in the laboratory's international archive were necessary, since it is impossible to directly observe what Earth's climate might be without modern industry, he said.
Santer questioned U.S. government statements in 2005 that rising global temperatures were due entirely to natural fluctuations.
His study did not deal with questions raised by Chris Landsea of the U.S. National Hurricane Center about whether there has actually has been an dramatic increase in hurricane intensity in recent years. Landsea said the historical record is unreliable.
Santer and his colleagues did not address the historical hurricane intensity record.