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Floating Arctic Ice Shrinking at Record Rate    [

    Warming Lull, Then New Records, Model Predicts
    MSNBC News

    Thursday 09 August 2007

10-year forecast expects several years will top 1998 as warmest year.

    Washington - Global warming will slow during the next few years but then speed up again, and that at least half of the years after 2009 will be warmer than 1998, the warmest year on record, scientists predicted in a study published Thursday.

    Climate experts have long predicted a general warming trend over the 21st century spurred by the greenhouse effect, but this new study gets more specific about what is likely to happen in the decade that started in 2005.

    To make this kind of prediction, researchers at Britain's Met Office - which deals with weather and climate issues - made a computer model that takes into account such natural phenomena as the El Nino pattern in the Pacific Ocean and other fluctuations in ocean circulation and heat content.

    A forecast of the next decade is particularly useful, because climate could be dominated over this period by these natural changes, rather than human-caused global warming, study author Douglas Smith said by telephone.

    In research published in the journal Science, Smith and his colleagues predicted that the next three or four years would show little warming despite an overall forecast that saw warming over the decade.

    "There is ... particular interest in the coming decade, which represents a key planning horizon for infrastructure upgrades, insurance, energy policy and business development," Smith and his co-authors noted.

    The real heat will start after 2009, they said.

    Until then, the natural forces will offset the expected warming caused by human activities, such as the burning of fossil fuels, which releases the greenhouse gas carbon dioxide.

    To check their models, the scientists used a series of "hindcasts" - forecasts that look back in time - going back to 1982, and compared what their models predicted with what actually occurred.

    Factoring in the natural variability of ocean currents and temperature fluctuations yielded an accurate picture, the researchers found. This differed from other models which mainly considered human-caused climate change.

    "Over the 100-year timescale, the main change is going to come from greenhouse gases that will dominate natural variability, but in the coming 10 years the natural internal variability is comparable," Smith said.

    While the Met Office considers 1998 as the warmest year on record, the U.S. National Climate Data Center ranked 2005 in a virtual tie with 1998.

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    Reuters contributed to this report.

 

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    Floating Arctic Ice Shrinking at Record Rate
    By Andrew C. Revkin
    The International Herald Tribune

    Thursday 09 August 2007

    The area of floating ice in the Arctic has shrunk more than in any summer since satellite tracking began in 1979, and it has reached that record point a month before the annual ice pullback typically peaks, experts said.

    The cause is probably a mix of natural fluctuations, like unusually sunny conditions in June and July, and long-term warming from heat-trapping greenhouse gases and sooty particles accumulating in the air, according to several scientists.

    William Chapman, who monitors the region at the University of Illinois Urbana-Champaign and posted a Web report on the ice retreat , said that only an abrupt change in conditions could prevent far more melting before the 24-hour sun of the boreal summer sets in September.

    "The melting rate during June and July this year was simply incredible," Chapman said. "And then you've got this exposed black ocean soaking up sunlight and you wonder what, if anything, could cause it to reverse course."

    Mark Serreze, a sea-ice expert at the National Snow and Ice Data Center in Boulder, Colorado, said his center's estimates differed somewhat from those of the Illinois team, and by the ice center's reckoning the retreat had not yet surpassed the satellite-era record set in 2005.

    But it was close even by their calculations he said, adding that it is almost certain that by September, there will be more open water in the Arctic than has been seen for a very long time. Ice experts at NASA and the University of Washington echoed his assessment.

    Serreze said that a high-pressure system parked over the Arctic appeared to have caused a "triple whammy" - keeping away clouds, causing winds to carry warm air north and pushing sea ice away from Siberia, exposing huge areas of open water.

    The progressive summertime opening of the Arctic has intensified a longstanding international tug of war over shipping routes and possible oil and gas deposits beneath the Arctic Ocean seabed.

    Last week, Russians in two mini-submarines planted a flag on the seabed at the North Pole. On Wednesday, Stephen Harper, the Canadian prime minister, kicked off a tour of Canada's Arctic holdings, pledging "to vigorously protect our Arctic sovereignty as international interest in the region increases."

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