Is the radiator in Europe likely to fail? The thermohaline circulation, thanks to which warm waters come from the south up the Atlantic Ocean to the north, bringing a mild weather to Europe, show signs of weakness, according to a new study published today in the journal Nature. These ocean currents are closely monitored and several studies have attempted to measure their evolution. The study of the climate over several thousand years has revealed that the stopping or acceleration of this oceanic circulation was implicated in major climatic changes.
Harry Bryden, of the Southampton National Oceanographic Center (GB), and his colleagues sailed between the Bahamas and the Canaries in the spring 2004 to measure studying these currents that form the 'southern reversal circulation' of the Atlantic Ocean. Comparable measurements made in 1957, 1981, 1992 or 1998 had revealed few changes, says Bryden. On the other hand, the 2004 campaign shows that the whole thermohaline circulation has slowed by 30%. If the Gulf Stream, on the surface, evolves very little, the deepest currents would have decreased by 50%.
Researchers tempered their results by pointing out that it is difficult to know if this is a short or long-term trend. Sensors have been installed in 25 different points of the subtropical Atlantic to monitor deep currents, say Nature. This monitoring should provide new results in the coming years.