Friday, September 11, 2009

NYC braces for risk of higher seas

Sea level may rise faster near New York than at most other densely populated ports due to local effects of gravity, water density and ocean currents, according to four new forecasts of melting ice sheets. The forecasts are the work of international research teams that included the University of Toronto, the National Center for Atmospheric Research in Boulder, Colo., Florida State University and the University of Bristol in the U.K., among others.

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  • prompted by a possibility of floods from higher seas, some university-based marine researchers and civil engineers are debating whether New York ought to protect its low-lying financial district, port, power grid and subways with storm surge barriers like the mobile bulwarks that safeguard London, Rotterdam, Netherlands, and St. Petersburg, Russia.

    While most of New York is above sea level, its subways, telecommunications cables, fiber-optics networks, plumbing and power mains aren't. "There is so much underground," says urban water management consultant Piet Dircke at Arcadis, one of four engineering firms that recently developed concepts for a storm surge barrier here. "The economic impact of flooding could be huge."

    Indeed, some civil engineers argue the city already risks catastrophic storm flooding. "A storm surge is not really a global warming issue" for New York, says senior engineer Dennis Padron at Halcrow Inc., which helped design a 15-mile-long storm barrier in St. Petersburg. "It could happen tomorrow."

    To be sure, the city that never sleeps is rarely dry even now. Every day, transit crews pump 14 million gallons of water from city subways. Authorities recently installed $400 million of more powerful pumps. Last year, they started installing higher sidewalk grates -- disguised as street art, bike racks and benches -- to help keep storm water away from subway rails.

    I saw one of those grates, two, actually, on the south side of Hillside Avenue, between 183rd and 184th Streets; I went to a Guyanan-West Indian-Chinese restaurant for dinner (got curry chicken, which was superb, and roti, which was hot and great for mopping up the curry gravy). The food cost $8.05, and was superb, and quite a bargain for a filling meal.

    In their efforts, Mr. Aggarwala and his colleagues have been guided by a panel of city-appointed climate experts from NASA and Columbia University, whose report predicts that by 2080 New York will have the climate Raleigh, N.C., has today. By their estimate, it will be about seven degrees Fahrenheit warmer and sea level may be two feet higher, unless polar ice sheets do melt.

    Balmy, and mild winter; too bad I won't be around to enjoy that.

    But such forecasts can be overtaken by new data. "You have to continually update plans as the models get better and the knowledge gets better and the unknowns become known," Mr. Aggarwala says.

    Generally, sea level today varies from place to place. The North Atlantic normally is two feet lower than the northern Pacific, because Atlantic sea water is colder, denser and saltier. This summer, weakened currents and persistent winds, for instance, caused sea level along the U.S. eastern seaboard to be two feet higher than normal, the National Oceanic and Atmospheric Administration reported last week.

    By taking such factors into account, researchers earlier this year calculated that melting Greenland glaciers could shift ocean currents enough to make sea level along New York's 570 miles of shoreline an additional 20 inches higher than seas elsewhere. "It will cause the sea level along the coastal region of the Northeast U.S. to rise faster," says climate modeler Aixue Hu at the National Center for Atmospheric Research in Boulder, Colo.
    Recommended Reading

    At Florida State University, climate forecasters reported variations in rising seas in USA Model projections of rapid sea-level rise on the northeast coast of the United States in Nature Geoscience.

    In Geophysical Research Letters, climate researchers estimated the impact of melting Greenland glaciers in Transient response of the MOC and climate to potential melting of the Greenland Ice Sheet in the 21st century.

    At the University of Toronto, researchers estimated higher sea levels along the U.S. coast from Antarctica's melting ice sheets in The Sea-Level Fingerprint of West Antarctic Collapse, published in Science.

    Researchers at the University of Bristol reported on especially high seas along the U.S. Pacific and Atlantic seaboards in Reassessment of the Potential Sea-Level Rise from a Collapse of the West Antarctic Ice Sheet in Science.

    At Columbia University, the Center for Climate Systems Research monitors hurricanes, sea level rise, and New York City.

    The Urban Ocean Observatory at the Center for Maritime Systems at the Stevens Institute of Technology tracks ocean, weather, environmental, and vessel traffic conditions throughout the New York Harbor and New Jersey Coast regions.

    The Center for Remote Sensing of Ice Sheets shows rising seas world-wide under different climate change scenarios.

    At, maps show areas of New York and New Jersey that would be flooded at various stages of sea level rise.

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