How climate change may be worsening Hurricane Sandy

Jeremy Hance
mongabay.com
October 29, 2012


Hurricane Sandy near Jamaica. Sixty-nine people were killed in the Caribbean from the storm to date. Photo by: NOAA.

While scientists are still debating some fundamental questions regarding hurricanes and climate change (such as: will climate change cause more or less hurricanes?), there's no debating that a monster hurricane is now imperiling the U.S. East Coast. A few connections between a warmer world and Hurricane Sandy can certainly be made, however: rising sea levels are likely to worsen storm surges; warmer waters bring more rain to increase flooding; and hotter temperatures may allow the hurricane to push both seasonal and geographic boundaries.

"The sea surface temperatures along the Atlantic coast have been running at over 3C above normal for a region extending 800km off shore all the way from Florida to Canada. Global warming contributes 0.6C to this," writes climatologist Kevin Trenberth in an article today in The Conversation. "With every degree C, the water holding of the atmosphere goes up 7%, and the moisture provides fuel for the tropical storm, increases its intensity, and magnifies the rainfall by double that amount compared with normal conditions."

In other words, one of the main contributing factors to why Sandy has become so potentially destructive is because Atlantic Coast waters have a fever this fall: 3 degrees Celsius (5.4 degrees Fahrenheit) above average. As Trenberth points out, a portion (20 percent) of this temperature rise is directly attributable to climate change. These warmer waters off the coast of the Atlantic have also increased water vapor, creating a potential for greater amounts of rainfall.

In addition, climate change has globally caused sea levels to rise by about 0.6 to 1 millimeter every year due both to melting ice and warmer water expansion. But the sea level rise has been even more pronounced of the U.S. east coast. A study from this summer found that sea levels in the region have been rising on average 2 to 3.8 millimeters a year during the last sixty years. Scientists are as yet unsure why sea levels are rising faster there than elsewhere, but higher sea levels means more severe storm surges and a much greater possibility of catastrophic flooding.

Finally warmer temperatures in the ocean and atmosphere could be changing hurricane season and paths. Warmer weather in the north allows hurricanes to travel further than they usually would, while hotter seasons increase the chances of October hurricanes on the eastern seaboard, once a rarity.

In recent years, researchers have begun to question whether climate change will increase the likelihood of hurricanes in general with notable papers arguing both sides. But generally scientists agree that even if climate change doesn't increase the number of total hurricanes, it's likely to increase the really bad ones. In fact, a 2010 review paper in Nature Geoscience found that global warming will bump up the number of particularly intense hurricanes by 2-11 percent, hurricanes just like the "Frankenstorm" Sandy.

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