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Geoscientist: Hurricane Sandy a wake-up call

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NASA's Aqua satellite captured a visible image of Hurricane Sandy's massive circulation on October 29. Sandy covers 1.8 million square miles, from the Mid-Atlantic to the Ohio Valley, into Canada and New England. (Photo: NASA Goddard MODIS Rapid Response Team)

When Hurricane Sandy struck New York City on Monday October 29, AAAS Fellow Michael Oppenheimer, a professor of geosciences at Princeton University and resident New Yorker, was in the middle of it. Still without power at the time of this interview, he was able to charge his electronic devices at a place nearby so that he and his family could keep in touch with the world and find out the news.

Not surprisingly, the issue of climate change has been on the minds of many in the wake of Hurricane Sandy, even becoming a factor in a presidential election that has been quiet on the subject. AAASMC asked Oppenheimer about the role of global warming in regard to the unusually severe weather the U.S. has been experiencing the past few years.

AAASMC: When you look at the natural disasters in the U.S. in 2012 alone — Hurricane Sandy on the east coast, record heat in the Midwest, record wildfires, drought throughout much of the country, tornado outbreaks in January — it appears that natural disasters are becoming more numerous and more severe. Could we be experiencing some crazy but natural climate cycle, or is this in fact evidence of global warming?
Michael Oppenheimer, professor of geosciences at Princeton University:
I think it's both. Global warming is among the contributing factors, but it's not in my view the most important factor yet. I think it will become a dominant factor during this century if we don't reduce emissions and greenhouse gases.

There is an argument that there has been an increase in the frequency of high-intensity tropical storms hitting the U.S. over the last few decades, but we really aren't in a position to be able to attribute that change in a confident way to global warming. On the other hand, we do expect warming to increase the intensity of tropical storms in general in the future. How much of an increase is a matter of uncertainty.

What we can attribute with high confidence to human-induced global warming, and which was a key factor in this storm, is a rising sea level. The sea level's been rising for a hundred years, caused by the thermal expansion of warming seawater, melting of glaciers and the melting of ice sheets at the poles. This has added about a foot or more to sea level in New York City, and it was without a doubt a factor in making the storm surge — which was a record — worse than it would otherwise have been. I'm quite confident that while global warming didn't initiate this storm, it certainly made its impact worse.

AAASMC: Bloomberg Businessweek's Hurricane Sandy cover says in large letters "It's Global Warming, Stupid," and New York City Mayor Michael Bloomberg has endorsed President Obama in part because of his stance on the effects of climate change. Do you think Hurricane Sandy could be a wakeup call to more urgent government action in response to global warming?
Oppenheimer:
Sandy is a wake-up call, and there's a sense of urgency in the wake of an event like this, but I wonder how long people will stay awake. We're not prepared today for the storms that come at us, which have, in my view, a significant global warming component in many cases. Even without that component, we wouldn't be prepared for them. Global warming is building in a higher risk factor for these storms by making them more intense and raising the sea level, which creates a bigger storm surge.

Even if politicians didn't care about global warming, they shouldn't be sitting on their hands; but it's encouraging that many of them have identified global warming as a contributing factor — one factor we know will increase in the future. People making infrastructure decisions for a city have to make them with a view toward these storms getting worse. They have to start talking about it today, because it takes decades to plan and accumulate the resources to make some of these improvements.

That being said, there are things they can do that are relatively inexpensive that don't have a lot of political obstacles. In New York, there was a 100-year storm in 1992 which did lead to some changes to the subway entrances and the raising of sewage outfalls. But the City hasn't implemented longer term plans to ease the flood burden on the city. They haven't yet, to my knowledge, pursued a plan to increase the porosity of the roadways, for example. It's good to see Governor Cuomo, Mayor Bloomberg and other city and state leaders wake up to the challenge. But now we need to see them act.

AAASMC: In 1988, you testified before Congress about the dangers of the greenhouse effect and called for action; 24 years later, how critical is it now?
Oppenheimer:
It's more critical. We haven't wasted the 20 years in between, a lot has been done, but it's unfolding too slowly. U.S. emissions have in fact gone down since they peaked in 2006 or 2007, due to a variety of factors, and some of those factors include intentional policy, like raising the fuel economy standards.

We've got a good international architecture for dealing with climate change in the United Nations Framework Convention on Climate Change and Kyoto Protocol. So we are in a position to act. If recent surveys are to be believed, the public accepts that global warming is a threat and something should be done about it; but we haven't had the political leadership on this issue.

It was encouraging to see Mayor Bloomberg endorse the President on the basis of climate change as an issue. Regardless of who you vote for, it's interesting to see a mayor step forward and say, "This is a threat to my city and I want to endorse the leader who is more likely to do something about it." It raises the profile of the issue. These are all good developments, but the world is warming faster than our ability to implement policy.

AAASMC: The east coast in particular seems to be bearing the brunt of worsening storms, including tornadoes in New York City, hurricanes this year and last, and several large snowstorms in recent years. Is this the "new normal" for this region of the country?
Oppenheimer:
Weather is variable, and I hesitate to draw a conclusion about the cause of these events except in specific cases where I can say it with some confidence. I can say with confidence that the sea level is rising due to global warming. I can say with equal high confidence that we've been getting more heat waves due to global warming. I can say with high confidence that we've been getting more intense rainstorms due to global warming; I can't say much about tornadoes; or hurricanes, except that the latter are working on a higher sea level and that's driving the ocean in to places it's never been, for centuries or longer. So some of this is clearly affected by global warming and therefore that part of it is certainly the new normal. And it's only going to get worse, until emissions of the greenhouse gases have been cut substantially.

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NASA's Aqua satellite captured a visible image of Hurricane Sandy's massive circulation on October 29. Sandy covers 1.8 million square miles, from the Mid-Atlantic to the Ohio Valley, into Canada and New England. (Photo: NASA Goddard MODIS Rapid Response Team)
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Susan Borowski

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