Man-induced global warming brewed superstorm?

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The Jury Is Out But Experts Say ‘Sandy’ Should Be Seen As A Foretaste Of Trouble To Come As Seas Rise
Justin Gillis


From the darkened living rooms of Lower Manhattan to the wave-battered shores of Lake Michigan, the question is occurring to millions of people at once: Did the enormous scale and damage from Hurricane Sandy have anything to do with climate change?
Hesitantly, climate scientists offered an answer this week that is likely to satisfy no one, themselves included. They simply do not know for sure if the storm was caused or made worse by human-induced global warming.
They do know, however, that the resulting storm surge along the Atlantic coast was almost certainly intensified by decades of sea-level rise linked to human emissions of greenhouse gases.
And they emphasized that hurricane Sandy, whatever its causes, should be seen as a foretaste of trouble to come as the seas rise faster, the risks of climate change accumulate and the political system fails to respond.
“We’re changing the environment — it’s very clear,” said Thomas R Knutson, a research meteorologist with the government’s Geophysical Fluid Dynamics Laboratory in Princeton, New Jersey.
By the time hurricane Sandy hit the Northeast coast on Monday, it had become a freakish hybrid of a large, late-season hurricane and a winter storm more typical of the middle latitudes. Though by no means unprecedented, that type of hybrid storm is rare enough that scientists have not studied whether it is likely to become more common in a warming climate.
“My profession hasn’t done its homework,” said Kerry A Emanuel, a climate scientist at the Massachusetts Institute of Technology. “I think there’s going to be a tonne of papers that come out of this, but it’s going to take a couple of years.”
Hurricanes draw their energy from warm waters in the top layer of the ocean. And scientists pointed out this week that parts of the western Atlantic were remarkably warm for late October.
Kevin E Trenberth, a scientist with the National Center for Atmospheric Research in Boulder, Colorado, said that natural variability probably accounted for most of that temperature extreme.
But, he added, human-induced global warming has raised the overall temperature of the ocean surface by about one degree Fahrenheit since the 1970s. So global warming probably contributed a notable fraction of the energy on which the storm thrived — maybe as much as 10%, he said.
He further said that many of Sandy’s odd features, including its large scale, derived from its origin as a merger of two weather systems that converged in the western Atlantic. “My view is that a lot of this is chance.”
Globally, the ocean rose about eight inches in the last century, and the rate seems to have accelerated to about a foot and scientists say most of the rise is a direct consequence of human-induced climate change. NYT NEWS SERVICE