There’s new data on Antarctica’s melting glaciers, and for anyone worried about the effects of climate change, it’s cold comfort indeed.
A pair of studies by researchers at NASA and the University of California at Irvine (UCI) show that glaciers in the continent’s western region are growing thinner ― and retreating at the fastest rate ever observed.
“The fact that this is happening even in the cold Antarctic should ring like an alarm bell to everyone’s ears,” Dr. Eric Rignot, professor of earth system science at UCI and one of the researchers, told The Huffington Post in an email. “And we may have to convey that message 1,000 times before anyone hears it.”
For the first study, published Aug. 28, 2016, in the journal Geophysical Research Letters, scientists led by UCI’s Dr. Bernd Scheuchl examined satellite radar data on the grounding lines ― the boundaries where glaciers disconnect from the underlying bedrock and start to float in the ocean ― for three neighboring glaciers.
The data showed that, since 1996, Smith Glacier’s grounding line retreated at an annual rate of 1.24 miles per year and Pope’s at an annual rate of 0.31 mile per year, according to a press statement released by NASA.
Kohler Glacier actually advanced 1.24 miles since 2011, but that didn’t reassure Scheuchl.
The unusual topography under that glacier helps guard against grounding line retreat, he told HuffPost in an email. What’s more, he said, “The advance is also very small compared to the retreat of Smith Glacier.”
In any case, the very different rates of glacial retreat seen in Scheuchl’s study led Ala Khazendar, a scientist at the Jet Propulsion Lab in Pasadena, California, to measure ice loss at the bottoms of the glaciers using data from NASA’s Operation IceBridge and other airborne research programs.
Khazendar’s study, which was published Oct. 25, 2016, in the journal Nature Communications, revealed dramatic losses of ice from the ocean sides of the glaciers’ grounding lines. The fastest-melting glacier, Smith, lost between 984 and 1,607 feet of ice thickness between 2002 and 2009.
That pace is nearly six times faster than a previous estimate.
The study relied on radar- and laser-based measurements, and both confirmed the glaciers’ ice loss.
”If I had been using data from only one instrument, I wouldn’t have believed what I was looking at, because the thinning was so large,” Khazendar said in the statement.
He added that Smith’s rapid melting and retreating were likely related to the shape of its underlying bedrock, which makes it easy for warm water to flow under the glacier because it slopes downward toward the interior of the continent. Pope and Kohler are on bedrock that slopes upward toward the Antarctic interior.
What’s next? For scientists, Scheuchel said, the challenge will be to estimate more precisely how glacier melt in Antarctica is contributing to sea level rise.
And for world leaders charged with protecting the planet against runaway climate change?
“Political processes are already underway (the Paris Climate Agreement will go into full force next month),” Scheuchel said in the email. “My hope is for politicians to take the issue and the corresponding science serious when they make their decisions.”
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