Indian Ocean current 'could save British climate'

April 30, 2011 - 0:0

Many climatologists believe global warming will stop the Gulf Stream, which keeps Britain much warmer than other countries on a similar latitude, and plunge it into an Alaskan-type climate.

The theory is that global warming will increase the rate of fresh water ice melting in the Arctic Ocean, which will make parts of the North Atlantic less saline and stop the deep water current that helps drive the Gulf Stream.
Four years ago the UN’s Intergovernmental Panel on Climate Change (IPCC) even said global warming was “very likely” to slow the current.
The theory was dramatized - with limited success - in the 2004 disaster movie The Day After Tomorrow, which sees a massive snowstorm engulfing New York.
But now oceanographers have found that the Agulhas current, which runs down the east coast of Africa, is spilling increasing quantities of warm, salty water into the South Atlantic.
Huge eddies of warm water are spinning out westwards, past the Cape of Good Hope, where they get swept northwards by the cold Benguela current. Eventually the 'Indian Ocean' water ends up in the North Atlantic - where scientists say it could “stabilize” the effect of melting ice.
Lisa Beal, of the University of Miami's Rosenstiel School of Marine and Atmospheric Science, explained that most of the water in the Agulhas current never made it into the Atlantic.
But climate change had strengthened the current, leading to bigger and more frequent swirls off the tip of Africa and more “Agulhas leakage” into the Atlantic.
Every decade, the flow from the Agulhas system into the Atlantic could be increasing by 1.4 million to 4 million cubic meters of water per second, she and colleagues wrote in the journal Nature. She said: “This could mean that current IPCC model predictions for the next century are wrong, and there will be no cooling in the North Atlantic to partially offset the effects of global climate change over North America and Europe.
“Instead, increasing Agulhas leakage could stabilize the oceanic heat transport carried by the Atlantic overturning circulation.” Eric Itsweire, director of the U.S.'s National Science Foundation physical oceanography program, which funded the research, added: “Under a warming climate the Agulhas Current system near the tip of South Africa could bring more warm salty water from the Indian to the Atlantic Ocean and counteract opposing effects from the Arctic Ocean.”
The historical record also indicates there have been dramatic peaks in “Agulhas leakage” over the last 500,000 years, according to the report.
Daily telegraph