12 September 2006The New York Times
Rising ocean temperatures linked by some studies to tropical storms are very likely a result of global warming caused by greenhouse gas emissions, according to new research.
The lead author of the new study, Benjamin D. Santer of the Lawrence Livermore National Laboratory of the Energy Department, said the findings suggested that further warming would probably make hurricanes stronger in coming decades.
But while environmentalists and some researchers have asserted that storms like Hurricane Katrina were already measurably stronger because of warming caused by humans, Dr. Santer said his study did not address that issue.
The study was published online yesterday by The Proceedings of the National Academy of Sciences.
The researchers compared a century of observed temperature changes with those produced in more than 80 computer simulations of how oceans respond to natural and human influences on the climate. The simulations were generated on 22 different computer models at 15 different research centers.
The simulations correctly mimicked the cooling caused by plumes from volcanic eruptions, which temporarily block the sun. At the same time, the authors said, the only warming influence that could explain the changes in the oceans was the buildup of heat-trapping smokestack and tailpipe gases in the air.
Earlier studies concluded that greenhouse gases from human activities were warming the oceans, but this analysis was the first to examine thoroughly trends in particular tropical regions of the Atlantic and Pacific Oceans that serve as nurseries for the destructive storms.
Several climate experts said that while debate persisted about the role of warming in pumping up hurricanes, there was little doubt about the long-term trend should warming continue as projected.
“Even under modest scenarios for emissions, we’re talking about sea surface temperature changes in these regions of a couple of degrees,” Dr. Santer said. “That’s much larger than anything we’ve already experienced, and that is worrying.”
