Why Climate Change Could Make Hurricane Impact Worse

Hurricane Katrina surprised disaster preparedness authorities when it made landfall 10 years ago, leveling entire communities and killing more than 1,800 people. The storm caused more than $100 billion in damage, making it the costliest natural disaster in U.S. history. But for all the damage the storm caused in New Orleans, Katrina was a relatively weak hurricane when it hit the city.

In the academic community, the unexpected disaster prompted climate scientists to consider the link between climate change and storms.  Since then, research has shown that climate change will increase the devastation caused by hurricanes as sea levels rise due to global warming.  Some research has also suggested that climate change has increased the intensity and frequency of storms.

The phenomenon of storm surge plays an essential role in the worsening effect of hurricanes. Storm surge occurs when waters rise above their normal level during a storm and wind and weather conditions push that water onto shore.  Thanks to global warming and rising sea levels, the potential for ocean water to be washed ashore by a storm surge has risen as well.

During Katrina, storm surge pushed ashore the water, causing levees to fail.  The storm was recorded as a hurricane of category 1 or category 2 strength when it hit New Orleans, relatively weak for such a devastating hurricane.  But the storm surge reached as high as 12 feet in some places, creating flood conditions across the city and wreaking havoc with the city’s levee system.  Hurricane Sandy, which hit the New York City in 2012, cost $2 billion more due to sea level rise than it would have otherwise, according to a RAND report.

“The strong winds in Katrina essentially blew water from the gulf up across southern Louisiana,” said Hugh Roberts, associate vice president at ARCADIS, a firm that has consulted on Louisiana’s rebuilding efforts.  “Once it hits land, it begins to build up.”

In the future, rising sea levels will only exacerbate the storm surge problem.  Around the globe, sea levels are estimated to rise 1 to 3 feet by 2100 due to climate change, and researchers say that in places like New Orleans 1 foot of sea level rise may lead to a 3 or 4 foot storm surge rise.
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“There is not uncertainty about sea level rise,” said RAND researcher Jordan Fischbach, who led a Louisiana flood risk assessment team.  “As we get more sea level rise, these large storm events will with certainty damage to assets and people.”

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