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1-Degree-Celsius Warming Would Lead to More Katrina-Like Storm Surges

By Stephanie Paige Ogburn, E&E reporter
3/19/2013 7:05:04 AM

A 1-degree-Celsius rise in global temperatures from 1990 levels would mean the Atlantic coast would experience two to seven times more Hurricane Katrina-size storm surges, researchers reported in a paper released yesterday in the journal Proceedings of the National Academy of Sciences.

The Ninth Ward of New Orleans after Hurricane Katrina. Photo by Brian Nolan.

Predicting how hurricanes will change as the globe warms has historically been a difficult task because historical data on hurricane strength are relatively unreliable. In order to get around this problem, Aslak Grinsted, a researcher from the Centre for Ice and Climate in Copenhagen, Denmark, turned to a new source of data.

Grinsted looked at storm surges as recorded by six long high-frequency tide-gauge records in the U.S. Southeast. These records, which went back to 1923, provided an accurate recording of large storm surges, which accompany hurricanes making landfall.

He then constructed a model using those data and global temperatures to understand how big storm surges correlate with temperatures. The results point to more big hurricanes as the temperature increases.

John Moore, a co-author of the paper who researches climate at Beijing Normal University and holds posts at the University of Lapland and Uppsala University in Sweden, also highlighted the finding that "the stronger the hurricane, the larger the sensitivity to temperature rises."

Grinsted said he turned to the tide gauges as a data source to measure historical hurricane strength after seeing that the hurricane research community was debating how climate will affect hurricanes.

"Then I realized I could get good data from the tide gauges and I could perhaps shed some light on it."

Creative approach to devastating problem

Greg Holland, a senior scientist at the National Center for Atmospheric Research whose work focuses on hurricanes and tropical meteorology, praised the paper's authors for trying to get at the problem of how temperatures will affect big hurricanes by using different data.

"It's a creative approach that really helps us understand how weather in general is changing," he said.

Holland noted that their finding is significant in that the increase in Katrina-like storms is higher than previous work has predicted.

The increase in big surges found in the paper was questioned in part by James Elsner of Florida State University, another expert on climate and weather.

Elsner said he appreciated the researchers' work in looking at a new source of data and saw their analysis as a useful first step, but also said their model could be refined and may have overstated how common big storm surges would be in the future.

"These estimates of Katrina-like storms being more common by a factor of two to seven is probably an overestimation," Elsner said.

"I do think that as the atmosphere warms, the storm surges will get stronger, but I don't think it's the definitive [finding] of how much stronger," he added.

Outcome in Pacific could be different

NCAR's Holland pointed out that others will refine the work as the scientific community absorbs this new finding. He was interested in how this technique could be applied to other places where hurricanes fall that have their own set of storm surge records.

"If this technique works, go everywhere there are storm surges. The Pacific region, the Australian region, the Indian Ocean region," he said. "We now have a technique that can be applied much more widely, and the more widely you apply it, the more accurate you get."

Moore, the paper's co-author, said he and Grinsted do plan to look at Pacific storm surge records to learn what the relationship is between Pacific typhoons and temperature.

"We are very much interested in Chinese and Japanese records. With the rapid growth of coastal cities, especially in China, the surge threat is very important economically," Moore said.

However, Grinsted did say the data on storm surges in the Pacific might not be as good. He also does not know whether he will see the same relationship between temperature and Pacific typhoons.

"I'm not at all convinced the conclusions from this paper in the Atlantic will hold for the Pacific," he said.

Moore agreed.

"The relationships are probably pretty different from the Atlantic," he said. "Maybe it's one of the rare instances where the developed world gets more of a kick from climate change than the developing world does."

Reprinted from ClimateWire with permission from Environment & Energy Publishing, LLC. 202-628-6500. E&E Publishing is the leading source for comprehensive, daily coverage of environmental and energy issues. Click here to start a free trial to E&E's information services.

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