Knutson said NOAA scientists hope to eventually conduct hurricane studies based only on ocean temperatures, which have been tracked reliably for many decades and which would greatly extend the hurricane database.
Hurricanes can form only when water temperatures reach at least 80 degrees Fahrenheit (about 27 degrees Celsius), making ocean data a valuable tool for understanding the dynamics of hurricane formation.
Debate Blows On
The debate over hurricanes and global warming took off in 2005, when a record 28 tropical storms formed in the Atlantic. Several were among the most powerful storms on record, including Hurricane Katrina, which devastated New Orleans.
Some scientists say that the stormy summers of 2004 and 2005 were an indication that global warming is causing more—and more powerful—hurricanes.
Other scientists have said that global warming's effect is minimal, if it exists at all.
Kerry Emanuel, a meteorologist at the Massachusetts Institute of Technology in Cambridge, has been among the scientists who see a direct link between global warming and hurricanes.
The latest NOAA study is "a good study, but the results should be taken with a grain of salt," Emanuel said. "It's good work, but it's premature."
He added that several problems and inconsistencies need to be solved before a reliable evaluation of global warming's effect on hurricanes can be accomplished.
In addition to the scarcity of detailed information about late-19th and early-20th century storms, Emanuel said that variations in how different computer models analyze the same data need to be resolved.
"My feeling is that our understanding of the problem will gradually get better as we pursue all approaches," he said. "It's unlikely that there will be a colossal breakthrough, but it will proceed in steps."
NOAA meteorologist Chris Landsea is science operations officer at the National Hurricane Center in Miami. He did not participate in the study conducted by NOAA's Knutson, but said he thought it was "an excellent new study."
"To me, this reconfirms all of the previous studies that suggest a very tiny change in hurricane intensity and rainfall," Landsea said.
Max Mayfield, hurricane specialist at WPLG-TV in Miami and a former director of the National Hurricane Center, declined to speak on the study's results.
"All I can say," he commented, "is that the debate goes on."
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