Hurricane Breeding Grounds Heat Up

Human activities affect ocean temperatures in areas where hurricanes form

September 12, 2006
Rising ocean temperatures in hurricane breeding grounds of the Atlantic and Pacific Oceans are unlikely to be purely natural, according to a study published online in the Sept. 11 issue of the journal Proceedings of the National Academy of Sciences (PNAS).

Using 22 different computer models of the climate system, scientists Benjamin Santer of the Lawrence Livermore National Laboratory and Tom Wigley from the National Center for Atmospheric Research (NCAR) in Boulder, Colo., along with researchers from nine other centers, show the warming of the tropical Atlantic and Pacific Oceans over the past century is linked to human activities.

The research is funded by the National Science Foundation (NSF).

“We’ve used virtually all the world’s climate models to study the causes of SST [sea surface temperature] changes in hurricane formation regions,” Santer says.

For the period between 1906 and 2005, the researchers found an 84 percent probability that human-induced factors--primarily an increase in greenhouse gas emissions--account for at least 67 percent of the observed rise in SSTs in the Atlantic and Pacific hurricane formation regions.

Research published during the past year has uncovered evidence of a link between rising ocean temperatures and increases in hurricane intensity. This has raised concerns about the causes of the rising temperatures, particularly in parts of the Atlantic and Pacific where hurricanes and other tropical cyclones form.

“The important conclusion is that observed SST increases in these hurricane breeding grounds cannot be explained by natural processes alone,” says Wigley. “The best explanation for these changes has to include a large human influence.”

Hurricanes are complex phenomena influenced by a variety of physical factors, such as SSTs, wind shear, water vapor, and atmospheric stability. The increasing SSTs in the Atlantic and Pacific hurricane formation regions are not the sole determinant of hurricane intensity, but they are likely to be one of the most significant influences.

“It is important to note that we expect global temperatures and SSTs to continue to increase over the next century,” Wigley says. According to Santer, “In a post-Katrina world, we need to do the best job we possibly can to understand the complex influences on hurricane intensity, and how our actions are changing those influences.”

Scientists at other institutions also contributed to the study: their affiliations include the University of California, Merced; Lawrence Berkeley National Laboratory; Scripps Institution of Oceanography; the University of Hamburg; the University of East Anglia; Manchester University; NASA’s Goddard Institute for Space Studies; and NOAA’s National Climatic Data Center.

-NSF-

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering, with an annual budget of $5.58 billion. NSF funds reach all 50 states through grants to nearly 1,700 universities and institutions. Each year, NSF receives about 40,000 competitive requests for funding, and makes nearly 10,000 new funding awards. The NSF also awards over $400 million in professional and service contracts yearly.

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