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Severe Storm Surges Projected to Increase

Damaged tourist attractions at Seaside Heights, New Jersey
Storm surges like those that resulted from Hurricane Sandy, which killed more than 250 people and damaged communities up and down the coastline of the Northeast—including the tourist attractions at Seaside Heights, New Jersey—are likely to occur more frequently in the future, thanks to global climate change. Wikimedia Commons/Master Sgt. Mark C. Olsen/U.S. Air Force/New Jersey National Guard

Researchers have developed a new model for predicting the effects of climate change on hurricane storm surges and they are expecting outsized surges to become more common.

April 9, 2013—The massive storm surges seen when Hurricane Katrina slammed into the U.S. Gulf Coast have already become more likely because of climate change in the 20th century, and they will become two to seven times more likely in the decades to come if climate change models for the 21st century prove correct.

These are the conclusions of the research paper “Projected Atlantic Hurricane Surge Threat from Rising Temperatures,” published recently in the Proceedings of the National Academy of Sciences of the United States of America.

The research was conducted by Aslak Grinsted, Ph.D., of Denmark’s Centre for Ice and Climate, part of the University of Copenhagen’s Niels Bohr Institute; John C. Moore, Ph.D., of the Arctic Centre, part of Finland’s University of Lapland; and Svetlana Jevrejeva, Ph.D., of the National Oceanography Centre, which is located in the United Kingdom on the campus of the University of Liverpool.

Nearly 40 percent of the population of the United States—123 million people—live within 50 mi of a coastline, according to the National Oceanic and Atmospheric Administration. Another 10 million people are expected to move into coastal counties by 2020, highlighting the importance of elucidating the effects of rising global temperatures on hurricane activity and storm surge levels.

Surges are blamed for the majority of deaths in some of the deadliest hurricanes on record. Storm surges recorded during Katrina, for example, exceeded 20 ft along a large swath of the U.S. Gulf Coast. The heavy seawater, weighing more than 1,700 lb/cu yd, rushed in at about 15 mph, causing massive destruction. And Hurricane Sandy, in late 2012, took the lives of more than 250 people; economic losses are estimated at more than $75 billion.

Building on their work in an earlier paper released last year, “Homogeneous Record of Atlantic Hurricane Surge Threat since 1923,” the authors looked at a data set from six high-frequency tide gauges that have recorded hurricane activity in the Atlantic Ocean since 1923. Using the surge recorded during Katrina as a benchmark, they discerned a trend toward greater surges. They also noted that years with warmer surface temperatures have produced twice as many extreme surges as have colder years.

Predicting how climate change will affect Atlantic hurricanes is complex, the authors note. Although warmer temperatures are more likely to spawn hurricanes, some global warming models predict changes in wind shear that will make it more difficult for hurricanes to form. Models disagree about which factors will predominate.

The authors used the data set with different models to predict how rising global temperatures might affect hurricane activity. The research found that sea surface temperatures in an area of the Atlantic referred to as the Main Development Region best matched hurricane activity in the 20th century. The authors also developed a gridded global temperature model that gave the best match of any of the models to 20th-century activity.

The authors then used global warming projections a model developed at Beijing Normal University to predict the effect of expected warming on storm surges. The paper notes that while Katrina-strength surges had a return period of more than 100 years in 1900, that return period has already dropped to 10 years. By 2100, under the climate change parameters used in the paper, the return period for extreme surges could be a mere 2 years.

“The empirical evidence here demonstrates a greatly increased Atlantic hurricane surge threat in a warmer world,” the authors write. “The escalating threat from cyclone-driven storm surges is further exacerbated by rising sea level. Additionally, the observed recent increase in Atlantic coastal wave power is concomitant with these increases in surge index.”



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