Dramatic Changes Occuring in Gulf Stream?
Posted on December 2, 2005
Are changes already taking place in the Gulf Stream? New Scientist reports that a group of scientists have measured a major drop in the amount of warm water in the Gulf Stream.
Harry Bryden at the National Oceanography Centre in Southampton, UK, whose group carried out the analysis, says he is not yet sure if the change is temporary or signals a long-term trend. "We don't want to say the circulation will shut down," he told New Scientist. "But we are nervous about our findings. They have come as quite a surprise."Scientists have long feared that a reduction in the amount of warm water in the Gulf Stream or a disruption of the Gulf Stream could bring in a new ice age. An article last year in the Independent discussed this possibility.The North Atlantic is dominated by the Gulf Stream - currents that bring warm water north from the tropics. At around 40� north - the latitude of Portugal and New York - the current divides. Some water heads southwards in a surface current known as the subtropical gyre, while the rest continues north, leading to warming winds that raise European temperatures by 5ºC to 10ºC.
But when Bryden's team measured north-south heat flow last year, using a set of instruments strung across the Atlantic from the Canary Islands to the Bahamas, they found that the division of the waters appeared to have changed since previous surveys in 1957, 1981 and 1992. From the amount of water in the subtropical gyre and the flow southwards at depth, they calculate that the quantity of warm water flowing north had fallen by around 30%.
A report by the International Geosphere-Biosphere Programme in Sweden -- launched by Nobel prize-winner Professor Paul Crutzen and other top scientists -- warned last week that pollution threatened to "trigger changes with catastrophic consequences" like these.More data will be needed to see if this feared change is underway.Scientists have long expected that global warming could, paradoxically, cause a devastating cooling in Europe by disrupting the Gulf Stream, which brings as much heat to Britain in winter as the sun does: the US National Academy of Sciences has even described such abrupt, dramatic changes as "likely". But until now it has been thought that this would be at least a century away.
The new research, by scientists at the Centre for Environment, Fisheries and Acquaculture Science at Lowestoft and Canada's Bedford Institute of Oceanography, as well as Woods Hole, indicates that this may already be beginning to happen.