North and tropical Atlantic Ocean bringing climate change to Antarctica

Newswise via New York University: The gradual warming of the North and Tropical Atlantic Ocean is contributing to climate change in Antarctica, a team of New York University scientists has concluded. The findings, which rely on more than three decades of atmospheric data and appear in the journal Nature, show new ways in which distant regional conditions are contributing to Antarctic climate change.

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

...Using a time-series analysis, in which the scientists matched changes in the North and Tropical Atlantic’s SST with subsequent changes in Antarctic climate, the researchers found strong correlations. Specifically, they observed that warming Atlantic waters were followed by changes in sea-level pressure in the Antarctic’s Amundsen Sea. In addition, these warming patterns also preceded redistribution of sea ice between the Antarctic’s Ross and Amundsen-Bellingshausen-Weddell Seas.

...The first part of the study, using the observational data, found a link, or correlation, between the Atlantic and Antarctic data sets. But a correlation means simply that two things appear to happen in conjunction and does not explain what may be causing a phenomenon. The second used a global atmospheric model, which allowed the researchers to create a simulated warming of the North Atlantic. The model responded, as the researchers had suspected, 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," he said.

The study’s findings raise a number of deeper questions, such as, is Antarctic sea-ice change fundamentally different from the well-reported changes in the Arctic? In contrast to the sea-ice decline over the Arctic, Antarctic sea ice has not diminished. Rather, it has redistributed itself in ways that have perplexed scientists, with declines in some areas and increases in others....

The first flight of Operation Ice Bridge’s Antarctic campaign flew Oct. 16, 2009, along the Amundsen Coast. The aircraft’s downward-looking Digital Mapping System camera captured images of sea ice from an altitude of at least 20,000 feet.