Climate Change Does Not Affect Antarctic Ocean Due To Deep, Old Water

Climate change or human activities have not affected the Antarctic Ocean much, says a study by the University of Washington. Even as the rest of the planet warms up, the ocean in this area remains roughly at the same temperature.

A new study uses observations and climate models to point out that the unique currents around Antarctica tend to continuously pull "deep, old water" to the surface. This water did not touch the surface of the earth before the machine age. Hence, it has been isolated from climate change.

"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 Kyle Armour of the University of Washington and lead author of the study. "We show that it's for really simple reasons, and ocean currents are the hero here."

The reason for inconsistent warming in the Antarctic ocean is said to be churning seas mixing extra heat downward. However, the new study that studied the path of the missing heat said that the explanation does not really fit the theory.

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

Dyes in model simulations helped the team to comprehend that the seawater that underwent the maximum climate change had a tendency to collect near the North Pole, and Antarctica was not affected. Hence, global warming affected the Arctic ocean and sea ice the most.

"The oceans are acting to enhance warming in the Arctic while damping warming around Antarctica," Armour said. "You can't directly compare warming at the poles because it's occurring on top of very different ocean circulations."

Estimating the escape routes of the heat as well as the forces pushing the uneven temperatures at the poles is vital to help us examine climate change and global warming.

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

The findings were published in the May 30 issue of Nature Geoscience.