As rising temperatures continue to shrink the extent of Arctic summer sea-ice, there has been much speculation as to why the ice cover on the opposite side of the planet has expanded slightly in recent years. Now British scientists have found the explanation–and it’s related to climate change.
Using data gathered by U.S. military satellite-tracking of the motion of the Frozen Continent’s icepack between 1992 and 2010, the researchers have found a link between Antarctic winds and the growth of sea-ice in the Weddell, Cooperation and Ross seas.
The analysis, “Wind-driven Trends in Antarctic Sea-ice Drift,” was published online yesterday in the science journal Nature Geoscience.
“Sea-ice is constantly on the move; around Antarctica the ice is blown away from the continent by strong northward winds. Since 1992 this ice drift has changed. In some areas the export of ice away from Antarctica has doubled, while in others it has decreased significantly,” said lead author Paul Holland , of the British Antarctic Survey, in a news statement about the research.
“Until now these changes in ice drift were only speculated upon, using computer models of Antarctic winds,” Holland said. “This study of direct satellite observations shows the complexity of climate change. The total Antarctic sea-ice cover is increasing slowly, but individual regions are actually experiencing much larger gains and losses that are almost offsetting each other overall. We now know that these regional changes are caused by changes in the winds, which in turn affect the ice cover through changes in both ice drift and air temperature.”
The changes in ice drift also suggest large changes in the ocean surrounding Antarctica, which is very sensitive to the cold and salty water produced by sea-ice growth, Holland added.
The new research also helps explain why observed changes in the amount of sea-ice cover are so different in the two polar regions, BAS said in its statement. “The Arctic has experienced dramatic ice losses in recent decades while the overall ice extent in the Antarctic has increased slightly. However, this small Antarctic increase is actually the result of much larger regional increases and decreases, which are now shown to be caused by wind-driven changes.”
Co-author Ron Kwok, of the Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, said: “The Antarctic sea ice cover interacts with the global climate system very differently than that of the Arctic, and these results highlight the sensitivity of the Antarctic ice coverage to changes in the strength of the winds around the continent.”
There has been contrasting climate change observed across the Antarctic in recent decades, British Antarctic Survey said in its statement. “The Antarctic Peninsula has warmed as much as anywhere in the Southern Hemisphere, while East Antarctica has shown little change or even a small cooling around the coast. The new research improves understanding of present and future climate change. It is important to distinguish between the Antarctic Ice Sheet — glacial ice — which is losing volume, and Antarctic sea ice — frozen seawater — which is expanding.”
The research was funded by the Natural Environment Research Council (NERC) and National Aeronautics and Space Administration (NASA).
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