A summer melt caused by climate change is, counterintuitively, expanding Antarctic sea ice, scientists say.
A Dutch study published online in the Nature Geoscience journal said that sea ice around Antarctica has expanded at an accelerated rate of 1.9 percent per decade since 1985, unlike that in the Arctic region. It also notes that cool freshwater from melt underneath Antarctic ice shelves has insulated offshore sea ice from the ocean beneath, which is warming.
Because the melt water has a relatively low density, it accumulates in the top layer of the ocean, allowing for the cool surface waters to re-freeze more easily during fall and winter.
"Against the background of global climate warming, the expansion of Antarctic sea ice is an exceptional feature, which seems to be associated with decreasing sea surface temperatures in the Southern Ocean," Richard Bintanja, of the Royal Netherlands Meteorological Institute, wrote with his colleagues.
"We predict that this mechanism will be a sizable contributor to the factors that regionally and seasonally offset greenhouse warming and the associated sea ice retreat."
The researchers also suggest that the "negative feedback" effect explained in their study should continue in the future, whereby the cool melt water layer limits the amount of evaporated water from oceans that becomes snow in Antarctica.
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