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“At First We Didn’t Believe It”: Fast-Melting Greenland Glacier Starts Growing Again In Massive U-Turn
“At First We Didn’t Believe It”: Fast-Melting Greenland Glacier Starts Growing Again In Massive U-Turn
A large and fast-melting glacier in Greenland is growing again, according to a new NASA study. The Jakobshavn (YA-cob-shawv-en) glacier on Greenland’s west coast had reportedly been retreating by around 1.8 miles and thinning by nearly 130 feet annually in 2012. May 30, 2012, photo shows an iceberg in or just outside the Ilulissat fjord that likely calved from the Jakobshavn glacier in west Greenland. (Ian Joughin/Associated Press)
According to a study published in Monday’s peer-reviewed Nature Geoscience, however, the glacier began growing at about the same rate over the past two years. That said, the authors of the study swear it’s temporary.
“At first we didn’t believe it,” said lead author Ala Khazendar who works at NASA’s Jet Propulsion Laboratory (JPL). “We had pretty much assumed that Jakobshavn would just keep going on as it had over the last 20 years.”Jakobshavn glacier (photo: Google Earth)
Co-author Josh Willis said that while this is “good news” on a temporary basis, it’s still “bad news” over the long term because it means that ocean temperatures are a larger factor in the growth and melting of glaciers than previously thought.
“In the long run we’ll probably have to raise our predictions of sea level rise again,” says Willis, pointing to inevitable doom from man-made global warming.
“That was kind of a surprise. We kind of got used to a runaway system,” said Jason Box, a Geological Survey of Denmark and Greenland ice and climate scientist who was not involved in the study.
Think of the ocean temperatures near Greenland like an escalator that’s rising slowly from global warming, Khazendar said. But the natural North Atlantic Oscillation sometimes is like jumping down a few steps or jumping up a few steps. The water can get cooler and have effects, but in the long run it is getting warmer and the melting will be worse, he said.
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Ice Apocalypse
Ice Apocalypse
Rapid collapse of Antarctic glaciers could flood coastal cities by the end of this century.
In a remote region of Antarctica known as Pine Island Bay, 2,500 miles from the tip of South America, two glaciers hold human civilization hostage.
Stretching across a frozen plain more than 150 miles long, these glaciers, named Pine Island and Thwaites, have marched steadily for millennia toward the Amundsen Sea, part of the vast Southern Ocean. Further inland, the glaciers widen into a two-mile-thick reserve of ice covering an area the size of Texas.
There’s no doubt this ice will melt as the world warms. The vital question is when.
The glaciers of Pine Island Bay are two of the largest and fastest-melting in Antarctica. (A Rolling Stone feature earlier this year dubbed Thwaites “The Doomsday Glacier.”) Together, they act as a plug holding back enough ice to pour 11 feet of sea-level rise into the world’s oceans — an amount that would submerge every coastal city on the planet. For that reason, finding out how fast these glaciers will collapse is one of the most important scientific questions in the world today.
To figure that out, scientists have been looking back to the end of the last ice age, about 11,000 years ago, when global temperatures stood at roughly their current levels. The bad news? There’s growing evidence that the Pine Island Bay glaciers collapsed rapidly back then, flooding the world’s coastlines — partially the result of something called “marine ice-cliff instability.”
The ocean floor gets deeper toward the center of this part of Antarctica, so each new iceberg that breaks away exposes taller and taller cliffs. Ice gets so heavy that these taller cliffs can’t support their own weight. Once they start to crumble, the destruction would be unstoppable.
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