It seems that in spite of the global warming that melts the Arctic ice, the ocean around Antarctica maintains a persistent chill caused by ancient cold waters surfacing from the depths after hundreds of years.
According to a U.S. study, the Southern Ocean off Antarctica could be the last place on Earth to react to the man-made climate change, thanks to a lag of centuries that affects waters emerging from up to 5,000 meters deep.
A lot of people still doubt current scientific findings saying that human use of fossil fuels is the cause of an increasing warming of the planet.
This seeming paradox of expanding winter sea ice around Antarctica in recent decades and a rapid decrease of ice in the Arctic is something they often point to in their reasoning.
“Our findings are a step toward resolving the mystery,” explained senior author Kyle Armour of the University of Washington, Seattle, in the journal Nature Geoscience.
He noted the fact that cold water keeps surfacing helps to explain the fact that sea ice persists in large masses. However, it does not explain the trend of expanding, which other studies have associated with shifts in winds off the massive frozen continent.
The recent report found that warm waters in the Gulf Stream get colder as they flow north into the North Atlantic, then go under and loop south towards Antarctica as part of a great aquatic conveyor belt that completes once every few centuries.
In the end, winds in the Southern Ocean surrounding Antarctica send surface waters northwards and encourage the upwelling of the chill, ancient waters from the abyssal depths.
This could be an explanation for why the surface of the Southern Ocean has warmed by just 0.02 degree Celsius per decade since 1950, which is considerably less than the global average of 0.08 degrees.
Scientists are still unsure if the cold waters could also help in delaying the melting of ice locked up on the continent in Antarctica; one of the biggest worries is that the melt could sharply raise global sea levels.
Colin Summerhayes of the Scott Polar Research Institute, who was not involved in the study, said that “even water that cool is still warm enough to melt the ice at the base of the ice shelves.”
Image Source: Phys.org
