Why is the Antarctic Ocean unaffected by global warming? Puzzle solved!

The solution lies in the unique ocean currents that envelope Antarctica.  

Updated: Jun 01, 2016, 00:19 AM IST
Why is the Antarctic Ocean unaffected by global warming? Puzzle solved!

New York: It's a strange phenomenon if we consider why the waters surrounding the Antarctic region remains untouched by the haunting effects of global warming and climate change.

However, researchers saw this puzzle as an affirmative and have actually come up with an answer to the nagging question.

The solution lies in the unique ocean currents that envelope Antarctica. They continually pull deep and centuries-old seawater up to the surface, which last touched Earth's atmosphere before the machine age and so has not been warmed by the atmosphere since fossil fuels began contributing to greenhouse gases.

"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," said lead author Kyle Armour, assistant professor at University of Washington, in the US.

The Southern Ocean's water comes from such great depths, and from sources that are so distant, that it will take centuries before the water reaching the surface has experienced modern global warming, the researchers said.

Other places in the oceans, like the west coast of the Americas and the equator, draw seawater up from a few hundred meters depth, but that doesn't have the same effect.

"The Southern Ocean is unique because it's bringing water up from several thousand meters (as much as 2 miles)," Armour added in the paper published in the journal Nature Geoscience.

The researchers used data from Argo observational floats and other instruments to trace the path of the missing heat.

Previously it was thought that heat taken up at the surface would just mix downward, and that's the reason for the slow warming in Antartica.

"But the observations show that heat is actually being carried away from Antarctica, northward along the surface," Armour noted.

Gale-force westerly winds that constantly whip around Antarctica act to push surface water north, continually drawing up water from below.

"The oceans are acting to enhance warming in the Arctic while damping warming around Antarctica," Armour said.

Knowing where the extra heat trapped by greenhouse gases goes, and identifying why the poles are warming at different rates, will help to better predict temperatures in the future, the researchers said.

(With IANS inputs)