Study Ties Warming to Intense Hurricanes
Pastor Dale Morgan
Sep 12, 6:44 PM EDT
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Study Ties Warming to Intense Hurricanes*
By RANDOLPH E. SCHMID
AP Science Writer
WASHINGTON (AP) -- Most of the increase in ocean temperature that feeds
more intense hurricanes is a result of human-induced global warming,
says a study that one researcher says "closes the loop" between climate
change and powerful storms like Katrina.
A series of studies over the past year or so have shown an increase in
the power of hurricanes in the Atlantic and Pacific oceans, a
strengthening that storm experts say is tied to rising sea-surface
temperatures.
And most of that temperature increase can be blamed on global warming
caused by human activities such as automobile and industrial pollution,
scientists report in Wednesday's issue of Proceedings of the National
Academy of Sciences.
"The work that we've done kind of closes the loop here," said Tom Wigley
of the National Center for Atmospheric Research in Boulder, Colo., a
co-author of the paper.
"The important conclusion is that the observed (sea-surface temperature)
increases in these hurricane breeding grounds cannot be explained by
natural processes alone," said Wigley. "The best explanation for these
changes has to include a large human influence."
Benjamin Santer of Lawrence Livermore National Laboratory, Livermore,
Calif., plus Wigley and their team studied the relationship of climate
and hurricanes using 22 different climate models at 15 institutions
around the world.
Climate models are complex sets of mathematical equations that
high-speed computers use to simulate weather and climate and to forecast
changes. The researchers used them to run 80 different simulations
analyzing the response of sea-surface temperatures to a variety of
factors and then compared the results from the independent models.
While previous studies have looked at entire oceans, this work focused
on the smaller areas of the Atlantic and Pacific where tropical storms form.
This study builds a connection between the theoretical foundation of
global warming and changes that are being observed in those areas where
hurricanes are born, said Robert Corell of the American Meteorological
Society, who moderated a briefing on the work.
While they reported the connection between rising ocean temperatures and
increasing storm power, the researchers declined to predict future changes.
Asked if they would recommend changes in public policy, Greg Holland of
the National Center for Atmospheric Research said, "It is important to
note that we're not policymakers. Our role is to present the best
possible conclusions from the available evidence."
Kerry Emanuel, a hurricane expert at Massachusetts Institute of
Technology, added that regardless of global warming, the United States
does need to address problems in dealing with hurricanes ranging from
insurance to disaster response.
Not so sure of the findings was William M. Gray of Colorado State
University, a longtime hurricane expert who issues forecasts each year
of the expected number of storms.
Gray said the models do not deal with all necessary ocean processes and
called the report "a desperate attempt to keep the bandwagon going.
They've kept it going with global warming and now they want to keep it
going with hurricanes."
"I am very sure over the test of time it will not hold up," said Gray,
who was not part of the research team.
Philip Klotzbach, also of Colorado State, said that "sea-surface
temperatures have certainly warmed over the past century, and that there
is probably a human-induced component.
"To me, the big challenge is still determining what percentage is
natural and what percentage is caused by humans. This paper sheds some
light on that question; however, there is still a considerable amount of
uncertainty," he said.
Christopher Landsea, a meteorologist at the National Oceanic and
Atmospheric Administration's Hurricane Research Division in Miami,
praised the new paper as very well thought out.
But, he said, while the paper discusses sea-surface temperature
increases, it does not address the sensitivity of hurricanes to ocean
temperature changes or questions about hurricane records in prior years.
While studies by Emanuel in Nature and Peter J. Webster of the Georgia
Institute of Technology in Science reported increases in the most
powerful storms, Klotzbach challenged those findings in Geophysical
Research Letters, reporting only a small increase and suggesting that
may be due to improved observation technology.
Santer's research was funded by the Department of Energy.
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On the Net:
Proceedings of the National Academy of Sciences: http://www.pnas.org