Why Has The Antarctic Ocean Not Warmed? Old, Cold Water May Solve The Mystery

Posted: May 30 2016, 9:29pm CDT | by , Updated: May 31 2016, 8:30pm CDT, in News | Latest Science News


Why Antarctic Ocean has not Warmed? Old, Cold Water May Solve the Mystery
Model simulates rapid warming in the Arctic while Southern Ocean around Antarctica has not warmed much. Credit: K. Armour / UW

New research says that ocean currents are cooling Antarctica while the rest of the planet is heating up.

Man-man carbon dioxide emissions are warming Earth’s atmosphere faster than ever before, but surprisingly the Antarctic Ocean is not heating up at the same rate.

Now, a combine team of researchers from MIT and Washington University has tried to explain why the water around Antarctic stays cool while the rest of the planet is warming up.  Researchers have found that a unique mechanism is in place that is pulling deep, centuries-old water up to the surface while taking down the warmer water to the equator. The currents around Antarctica are continually bringing up that pristine seawater on the top that has not experienced fossil fuel related climate change ever.

“With rising carbon dioxide you would expect more warming at both poles, but we only see it at one of the poles, so something else must be going on,” said lead researcher Kyle Armour. “We show that it’s for really simple reasons and the ocean currents are hero here.”

The unique currents are balancing out things and making sure that Antarctic Ocean remains cool despite the influence of human-driven climate change almost everywhere else. The process is simple: Southern Ocean brings up the water from the depths that has last touched Earth’s atmosphere before the machine age and where it will take hundreds of thousands of years to reach the effects of global warming while the other places in the ocean are responsible for taking water exposed to climate change down at the depths.  

“The Southern Ocean is unique because it's bringing water up from several thousand meters (as much as 2 miles)” said Armour. “It's really deep, old water that's coming up to the surface, all around the continent. You have a lot of water coming to the surface, and that water hasn't seen the atmosphere for hundreds of years."

The warming of the Southern Ocean is much slower than the rest of the ocean and a previous research has shown that the surface temperature of the Southern ocean has warmed by just 0.002C per decade since 1950, compared to 0.08C per decade for the average of the global ocean surface. But the process was misunderstood and the core reasons were wrongly identified. 

“The old idea was that heat taken up at the surface would just mix downward, and that's the reason for the slow warming," said Armour. "But the observations show that heat is actually being carried away from Antarctica, northward along the surface."

For the study, researchers used data from Argo observational floats and other instruments to track where the ocean heat goes and found that the water that has experienced the most climate change tends to clump up around the North Pole, causing minimal changes in Antarctic Ocean. 

Since the cause has been identified why poles are warming at different rates, the findings will help better predict temperatures in future. 

“When we hear the term global warming, we think of warming everywhere at the same rate,” said Armour. “We are moving away this idea of global warming and more toward the idea of regional patterns of warming, which are strongly shaped by ocean currents.”



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Hira Bashir covers daily affairs around the world.




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