Europe's warming current has slowed: oceanographers
Last Updated Wed, 30 Nov 2005 17:59:28 EST
CBC News
The ocean currents that keep northern Europe warm have weakened, scientists say.
A system of currents called the Atlantic Conveyor carries warm upper water north from the Gulf Stream, while cold water is pushed to the bottom and travels south.
Scientists have theorized that the Atlantic Conveyor could slow if warming causes ice caps to melt, making the water less salty, less dense and unable to sink and flow back south.
Researchers in Britain found the conveyor has slowed about 30 per cent since 1957.
"What we find is that more of the Gulf Stream is recirculating southward and less is going into far northern latitudes," said Harry Bryden of the National Oceanography Centre in Southhampton.
In the last 48 years, five sets of temperature and salt measurements were taken at various depths at a latitude of 25 degrees north in the subtropical Atlantic.
No changes were found in the northward flow of warm water near the surface but its overall circulation system is slowing, the researchers report in Thursday's issue of the journal Nature.
The "analysis provides the first observational evidence that such a decrease of the oceanic overturning circulation is well underway," said Detlef Quadfasel of University of Hamburg in Germany. Quadfasel wasn't involved in the British study but he wrote a commentary about it in the journal Nature.
Climate models suggest increased levels of carbon dioxide in the atmosphere would further slow the current, but the data can't be directly linked to climate change, Bryden told a news conference. Researchers also can't tell if winds might compensate for the change.
At the present rate of slowdown, average temperatures in western Europe could drop by one to two degrees in 10 to 20 years, the researchers said.
In the past, such a drop in temperatures led to colder and more severe winters, said study co-author Meric Srokosz, science co-ordinator at the centre.
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