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New study shows impact of Antarctic Ice Sheet on climate change
http://oregonstate.edu/ua/ncs/archives/2016/dec/new-study-shows-impact-antarctic-ice-sheet-climate-change[font face=Serif][font size=5]New study shows impact of Antarctic Ice Sheet on climate change[/font]
12/12/2016
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“There is a natural variability in the deeper part of the ocean adjacent to the Antarctic Ice Sheet – similar to the Pacific Decadal Oscillation, or El Niño/La Niña but on a time scale of centuries – that causes small but significant changes in temperatures,” Schmittner said. “When the ocean temperatures warm, it causes more direct melting of the ice sheet below the surface, and it increases the number of icebergs that calve off the ice sheet.”
Those two factors combine to provide an influx of fresh water into the Southern Ocean during these warm regimes, according to Peter Clark, a paleoclimatologist in OSU’s College of Earth, Ocean, and Atmospheric Sciences and co-author on the study.
“The introduction of that cold, fresh water lessens the salinity and cools the surface temperatures, at the same time, stratifying the layers of water,” Clark said. “The cold, fresh water freezes more easily, creating additional sea ice despite warmer temperatures that are down hundreds of meters below the surface.”
The discovery may help explain why sea ice has expanded in the Southern Ocean despite global warming, the researchers say. The same phenomenon doesn’t occur in the Northern Hemisphere with the Greenland Ice Sheet because it is more landlocked and not subject to the same current shifts that affect the Antarctic Ice Sheet.
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http://dx.doi.org/10.1038/nature2058212/12/2016
[font size=3]…
“There is a natural variability in the deeper part of the ocean adjacent to the Antarctic Ice Sheet – similar to the Pacific Decadal Oscillation, or El Niño/La Niña but on a time scale of centuries – that causes small but significant changes in temperatures,” Schmittner said. “When the ocean temperatures warm, it causes more direct melting of the ice sheet below the surface, and it increases the number of icebergs that calve off the ice sheet.”
Those two factors combine to provide an influx of fresh water into the Southern Ocean during these warm regimes, according to Peter Clark, a paleoclimatologist in OSU’s College of Earth, Ocean, and Atmospheric Sciences and co-author on the study.
“The introduction of that cold, fresh water lessens the salinity and cools the surface temperatures, at the same time, stratifying the layers of water,” Clark said. “The cold, fresh water freezes more easily, creating additional sea ice despite warmer temperatures that are down hundreds of meters below the surface.”
The discovery may help explain why sea ice has expanded in the Southern Ocean despite global warming, the researchers say. The same phenomenon doesn’t occur in the Northern Hemisphere with the Greenland Ice Sheet because it is more landlocked and not subject to the same current shifts that affect the Antarctic Ice Sheet.
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