Findings may help explain changes in Antarctic sea ice patterns
By Summit Voice
FRISCO — A team of New York University scientists say they’ve found potential links between gradual warming of the North and Tropical Atlantic Ocean and climate changes in Antarctica.
The researchers reached their findings after carefully analyzing 30 years of data, helping to show how distant regional conditions are contributing to Antarctic climate change and redistribution of Antarctic sea ice.
“Our findings reveal a previously unknown, and surprisingm force behind climate change that is occurring deep in our southern hemisphere: the Atlantic Ocean,” said 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.”
Specifically, the scientists studied the North and Tropical Atlantic’s Sea Surface Temperature variability — changes in the ocean’s surface temperature — focusing on the last three decades. This metric, the Atlantic Multidecadal Oscillation, had previously not been considered in seeking explanations for Antarctic climate change.
When the scientists matched changes in North and Tropical Atlantic sea surface temperatures with subsequent changes in Antarctic climate, they found 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.
“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 David Holland, co-author of the study, a professor at NYU’s Courant Institute and past director of NYU’s Center for Atmospheric Ocean Science.
During recent decades, Antarctica has experienced dramatic climate change. The Antarctic Peninsula is warming faster than any other part of the globe. It has long been known that the region’s climate is affected, in part, by changes in the distant Pacific Ocean climate.
But the phenomena brought on by the Pacific have shorter-term influences—for instance, due to El Niño. Less understood are the longer-term forces that have produced warming along the Antarctic Peninsula or the sea-ice redistribution in the southern hemisphere’s winter over many decades.
Once they confirmed a link between the Atlantic and Antarctic data sets, the scientists simulated warming of the North Atlantic with a climate model.
“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,” Holland 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.
“From this study, we are learning just how Antarctic sea-ice redistributes itself, and also finding that the underlying mechanisms controlling Antarctic sea ice are completely distinct from those in the Arctic,” Holland said.