Day After Tomorrow on its way, but slower

06 October 2016 - 11:00 By DAVE CHAMBERS


In The Day After Tomorrow, starring Dennis Quaid and Jake Gyllenhaal, a new ice age arrives after the circulation of water in the Atlantic Ocean is disrupted. Now scientists have found that the circulation really is slowing down, with consequences for the climates of eastern North America and Western Europe.And they have found a surprising connection with the Agulhas current off South Africa's south-east coast, where warm Indian Ocean water flows south towards the Atlantic, then turns eastwards.Warm water that escapes into the Atlantic around the Cape is known as the Agulhas leakage. The new research shows the amount of leakage has changed over time, affecting the quantity of heat transported northward by the circulation."We've found that the two are connected, but I don't think we've found that one causes the other," said oceanographer Kathryn Kelly, of the University of Washington, in the US."It's more likely that whatever changed the Agulhas changed the whole system. And it doesn't work like in the movie. The slowdown is happening very gradually."The study, reported in journal Geophysical Research Letter, looked at data from satellites and ocean sensors off Miami that have tracked the "Atlantic overturning circulation" for more than a decade.The circulation process transports huge amounts of heat from low to high latitudes and has a major influence on climate.Its finding could have implications for northern European and eastern US climates, and for understanding how the oceans carry heat from the tropics towards the poles.Other research suggests that the Agulhas current, which in places is just 20km off the east coast, is intensifying and warming."South African scientists have shown that changes in sea surface temperatures south and west of Africa and the proximity of the Agulhas current to the coast impacts rainfall over the continent," said Juliet Hermes, from the South African Environmental Observation Network.Oceanographers have built "one of the world's most comprehensive observational networks" to monitor the current.

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