Once thought to be immune to the effects of global warming, the Zachariae glacier began shrinking rapidly in 2003 and has since lost more than 10 billion tons of ice per year, retreating by more than 12 miles.
Three years of exceptionally warm weather just after the turn of the 21st century broke the blockage that had kept the river of ice in place, according to a report published in the journal Nature Climate Change.
Historically, Zachariae flowed very slowly since it had to fight its way through a bay choked with floating ice.
That ice barrier is now reduced, allowing the glacier to flow and draw down vast amounts of ancient ice from the interior.
“Northeast Greenland is very cold. It used to be considered the last stable part of the Greenland ice sheet,” said Michael Bevis of Ohio State University, who led the study.
Greenland's ice cap has become a yardstick for global ocean rise because if it melted entirely, global sea levels would rise by about 23 feet.