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Shifting Ocean Currents Drive Accelerating Ice Melt of Antarctic Ice Shelf

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Shifting currents are eating away at the Pine Island Ice ShelfShifting ocean currents appear to be accelerating ice melt of the Pine Island Glacier Ice Shelf in western Antarctica.

According to research published this week in the journal Nature Geoscience, scientists from the Lamont-Doherty Earth Observatory at Columbia University have recorded ocean currents driving at and underneath the ice shelf, carving out an expanding cavity from underneath the glacier, creating a growing impact 50 percent greater than when scientists began monitoring the region in the early 1990’s.

Researchers estimate that 2.5 miles of glacier now slide into the sea annually.

In a summary report, scientists say the rapid rate of deterioration of the Pine Island Glacier could significantly impact coastlines around the globe:

“Pine Island Glacier, among other ice streams in Antarctica, is being closely watched for its potential to redraw coastlines worldwide. Global sea levels are currently rising at about 3 millimeters (.12 inches) a year. By one estimate, the total collapse of Pine Island Glacier and its tributaries could raise sea level by 24 centimeters (9 inches).”

The accelerating trend of ice can’t be accounted for solely from the modest 0.2 degree Celsius increase in surrounding ocean temperature observed at Pine Island over the past fifteen years. Scientists point to evidence of stronger winds in the Southern ocean that are shifting currents, pushing warmer waters from the tropics toward the ice shelf. That warmer water pushes further underneath the glacier, leading to the observed rate of destabilization and the growing chasm underneath.

Authors of the report cite the phenomenon impacting western Antarctica as further indication of the “multiplier effect” climate change has on regional ecosystems. Eric Rignot, a senior scientist a the NASA Jet Propulsion Laboratory who participated in the study, explained in a statement coinciding with the publication of the research:

“The main reason the glaciers are thinning in this region, we think, is the presence of warm waters,” said Rignot. “Warm waters did not get there because the ocean warmed up, but because of subtle changes in ocean circulation. Ocean circulation is key. This study reinforces this concept.”

Additional sources and further reading:
Climatewire (subscription required)

 

Image credit: NASA, courtesy Flickr

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