Global warming will make the New York metropolitan region not onlywarmer, but wetter as well, according to a new Columbia University study.
Subways, airports and low-lying coastal areas could experienceflooding if global warming produces more violent storms and higher sealevels, as expected, said Vivien Gornitz, associate research scientist atColumbia's Center for Climate Systems Research. Local temperatures couldrise by as much as four degrees Fahrenheit, and sea levels could increaseby up to eight inches by 2030 and by as much as four feet by 2100, underthe most extreme scenarios, she said.
Dr. Gornitz presented the new work at the Metro East Workshop, heldMarch 23-24 at Columbia, one in a series sponsored by the federalgovernment to assess regional vulnerability to climate change. Theresults, with reports from 18 other regions, will be presented to Congressand the president by 2000.
Dr. Gornitz, who is also affiliated with the National Aeronauticsand Space Administration's Goddard Institute for Space Studies, was joinedby co-authors Cynthia Rosenzweig, adjunct research scientist at the Centerfor Climate Systems Research; Chris Small, associate research scientist atColumbia's Lamont-Doherty Earth Observatory; Richard Goldberg, researchstaff assistant at the center, and David Rind, adjunct senior researchscientist at Lamont.
Dr. Gornitz presented three scenarios for the period 1995 to 2030:a low-change scenario that is her extrapolation of current trends withoutany greenhouse-induced warming; a middle ground, based on simulations fromthe Geophysical Fluid Dynamics Laboratory at Princeton University, and ahigh-change scenario developed at the Goddard Institute, called Business asUsual,that assumes greenhouse warming takes place without any mitigatingefforts. Temperatures in the metropolitan area increase over the period byone to four degrees Fahrenheit, according to the models. None of thescenarios finds significant increases in precipitation.
But all the scenarios show local sea-level rises, ranging from fourto eight inches by 2030, and maximum coastal flood heights of nearly sixfeet, an increase of nearly a foot from current levels. That means thatany area below six feet above sea level would be vulnerable to flooding,including most of the lower Manhattan shoreline, coastal and island areasof Jamaica Bay, much of downtown Hoboken and Jersey City and south shorebeaches in Staten Island and the Rockaways.
About an inch of the sea-level rise is really a ground-level fall,Dr. Gornitz said. The northeastern United States is dropping by about onemillimeter a year, offsetting a rise in southern Canada, which waspreviously compressed by glaciers. Local geological factors elsewhere maymitigate rising sea levels.
Scientists and policymakers may quibble over details, but when allmodels show significant sea-level rises, it's time to pay attention, Dr.Gornitz said. "Obviously, the best mitigating action would be to reducegreenhouse gases, but that is proving to be extremely difficult, becausemany countries must agree to limit their emissions," she said.
State and local planners should be thinking about countermeasuresnow, Dr. Gornitz said. Areas that are just above sea level, includingparts of lower Manhattan and New Jersey, could be protected with seawalls.Runways at Kennedy, LaGuardia and Newark airports could be raised aboveexpected flood levels. Pumping systems may be needed to keep the New YorkCity subways dry, and some coastal roadways, such as the West Side Highway,may need to be moved inland, she added. The Columbia scientist called forrezoning of coastal areas for parks and recreational uses, not high-densityresidential development.
Materials provided by Columbia University. Note: Content may be edited for style and length.
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