Warming Atlantic Ocean Contributing to Antarctic Climate Change

As the Atlantic Ocean warms in both its northern and tropical regions, it is contributing to climate change in Antarctica, a new study reveals.

Building upon three decades of atmospheric data, the study, which is published in the journal Nature, reveals new ways in which the climate on Antarctica is affected by distant regional conditions.

"Our findings reveal a previously unknown and surprising force behind climate change that is occurring deep in our southern hemisphere: the Atlantic Ocean," said lead study author Xichen Li, a doctoral student at New York University's Courant Institute of Mathematical Sciences. "Moreover, the study offers further confirmation that warming in one region can have far-reaching effects in another."

The climate change going on in Antarctica is dramatic. Over the last few decades researchers have documented the warming taking place on the Antarctic Peninsula as the strongest warming of any region on the planet.

Summertime Antarctic climate changes have been attributed to an increase in greenhouse gases coupled with stratospheric ozone loss. But sources of wintertime climate change have been less clear.

The bulk of climate change research in Antarctica has focused on how the Pacific Ocean is linked to climate change on the most southern continent. But the Atlantic Ocean, Li and his colleagues report, has been overlooked.

In their study the researchers looked specifically at the sea surface temperature (SST) variability in the North and tropical Atlantic Ocean.

When comparing changes in SST with changes in Antarctica's climate, the scientists found strong correlations, most notably that when Atlantic waters warmed, the sea-level pressure in Antarctica's Amundsen Sea also changed. The SST patterns could also be linked to a redistribution of sea ice between the Antarctic's Ross and Amundsen-Bellingshausen-Weddell Seas.

But the researchers were quick to note that correlation does not equal causation. Probing further, the team went on to use a global atmospheric model which they used to create a simulated warming of the North Atlantic. The model responded, as the scientists expected, by changing the climate in Antarctica.

"While our data analysis showed a correlation, it was the use of a state-of-the-art computer model that allowed us to see that North Atlantic warming was causing Antarctic climate change and not vice versa," said study co-author David Holland, a professor at NYU's Courant Institute.

The research was done in conjunction with the National Science Foundation.