As the world prepares for the most important global climate summit yet in Paris later this month, news from Greenland could add urgency to the negotiations. For another major glacier appears to have begun a rapid retreat into a deep underwater basin, a troubling sign previously noticed at Greenland’s Jakobshavn Glacier and also in the Amundsen Sea region of West Antarctica.
And in all of these cases, warm ocean waters reaching the deep bases of marine glaciers appears to be a major cause.
The new fast-moving glacier is the Zachariae glacier or Zachariæ Isstrøm, located in the far northeastern part of Greenland. In a new paper in Science, Jeremie Mouginot of the University of California-Irvine and his colleagues find that the ocean-based glacier, which contains 0.5 meters or a foot and a half of potential sea level rise, has begun a rapid retreat, especially since 2012. The glacier has lost fully 95 percent of the ice shelf that used to help stabilize it, they say, and now sports a 75 meter high ice cliff extending above the water (the glacier also extends hundreds of additional meters below it).
“This is sort of the second major floodgate from Greenland that has opened up,” says Eric Rignot of UC-Irvine and NASA’s Jet Propulsion Laboratory, one of the authors of the study. The first, says Rignot, was the Jakobshavn glacier, Greenland’s “fastest” moving, according to a recent study, which is currently based 1,300 meters below sea level and also retreating into a deep basin.
Now, at Zachariae, that seems to be happening again. In combination with its nearby neighbor, Nioghalvfjerdsfjorden glacier, the two glaciers contain a potential 1.1 meter of sea level rise (over 3 feet), so any change here is not good.
“If you see Greenland as a boat, it’s like we’re taking water from every side now,” says Mouginot.
“A disaster is unfolding in slow motion with important sea level rise implications,” says Jason Box, a professor with the Geological Survey of Denmark and Greenland, after reading the paper at the Post’s request.
The melting of the “Zachariae Isstrom” glacier is a result of warming temperatures both in the sea and the air, said study co-author Eric Rignot, also of UC-Irvine. “The top of the glacier is melting away as a result of decades of steadily increasing air temperatures, while its underside is compromised by currents carrying warmer ocean water, and the glacier is now breaking away into bits and pieces and retreating into deeper ground,” he said.
The glacier is near a large one also melting rapidly but at a slower rate. The two chunks of ice make up 12% of the Greenland ice sheet and would boost global sea levels by more than 39 inches if they both totally collapsed, a process that would likely take centuries.
The planet’s two major ice sheets are in Greenland and Antarctica, and together make up 99% of the freshwater ice on Earth, according to the National Snow and Ice Data Center. In Greenland, ice sheet decline continues to outpace accumulation, because warmer temperatures have led to increased melt and faster glacier movement at the island’s edges, the data center said.
“Not long ago, we wondered about the effect on sea levels if Earth’s major glaciers were to start retreating. We no longer need to wonder,” Rignot said. “For a couple of decades now, we’ve been able to directly observe the results of climate warming on polar glaciers. The changes are staggering and are now affecting the four corners of Greenland.”
Science Magazine – Fast retreat of Zachariæ Isstrøm, northeast Greenland
After 8 years of decay of its ice shelf, Zachariæ Isstrøm, a major glacier of northeast Greenland that holds a 0.5-meter sea-level rise equivalent, entered a phase of accelerated retreat in fall 2012. The acceleration rate of its ice velocity tripled, melting of its residual ice shelf and thinning of its grounded portion doubled, and calving is now occurring at its grounding line. Warmer air and ocean temperatures have caused the glacier to detach from a stabilizing sill and retreat rapidly along a downward-sloping, marine-based bed. Its equal-ice-volume neighbor, Nioghalvfjerdsfjorden, is also melting rapidly but retreating slowly along an upward-sloping bed. The destabilization of this marine-based sector will increase sea-level rise from the Greenland Ice Sheet for decades to come.
Remember when glacial pace meant really f’n slow?
“A disaster is unfolding in slow motion with important sea level rise implications,” says Jason Box, a professor with the Geological Survey of Denmark and Greenland, after reading the paper at the Post’s request.
How “scholarly” and “polite”, although he did manage to get the word “disaster ” in there. I’ll bet he really wanted to say something like “HOLY S**T! Our boys Jacob and Zachary and Nigel melting like this is going to put a lot of water into the oceans. Roll up your trouser legs, folks!”.
(Can anyone say “tipping points”? Or “If this worsens, we’re F**ked”?)
Miami certainly is and New Orleans
Box has been pretty open in the past:
This got Box in trouble with some fellow climatologists — who seemed to miss the conditional nature of his statement. One of them was James Hansen:
Others were Michael Mann and Gavin Schmidt. Of course there are plenty of individuals who do go around saying there is nothing that can be done — so I can understand their reaction. But Box isn’t among the people who such a critique can properly be directed.
Agreed. We here on Crock DID manage to see the big “IF” in Box’s original statement and commented then that it was conditional. I find it hard to understand why other climatologists missed that—-not very confidence inspiring. Hansen for one has said in as many words “We’re fucked IF we don’t get moving pretty soon on dealing with AGW and IF BAU continues”. What’s his problem? (and what’s HIS timeline for avoiding us getting “f**ked”)
I figured the West Antarctic ice sheet becoming unhinged from its grounding line would cause swift actions to be taken. Unfortunate a new contributor enters the sea level rise race.
If what GeoMapApp is telling me is true then those two dotted areas in that graphic illustration may as well be joined.
Here are two transect I obtained for using GeoMapApp which demonstrates that a large portion of Greenland is a below sea level basin. I have added a red dot to the profile side elevation to equate to the position of the red dots which appear on the transect when the pointer is placed over that profile side elevation:
http://lionels.orpheusweb.co.uk/Misc/GrTrans1.JPG
http://lionels.orpheusweb.co.uk/Misc/GrTrans2.JPG
It is easy to draw other transects to explore the topology further.
If what GeoMapApp is telling me is true then those two dotted areas in that graphic illustration may as well be joined.
Here is a transect I obtained by using GeoMapApp which demonstrates that a large portion of Greenland is a below sea level basin. I have added a red dot to the profile side elevation to equate to the position of the red dots which appear on the transect when the pointer is placed over that profile side elevation:
http://lionels.orpheusweb.co.uk/Misc/GrTrans2.JPG
It is easy to draw other transects to explore the topology further.
An earlier post appears to have fallen through the cracks.
Something that is not too clear in the lead graphic is that the ice sheet covers only ~80% of Greenland, so the NE Greenland Ice Stream is an even bigger deal than it appears at first glance. We are getting closer to “we’re f**ked” time.
“Something that is not too clear in the lead graphic is that the ice sheet covers only ~80% of Greenland…”
The pale grey area is that below sea level and to the edge of a continental shelf. Draw a transect off into deeper water, blue, and you will see what I mean.
But yes that NE Greenland Ice Stream goes into the below sea level centre of the ice sheet so is a worry. Explore Antarctica – esp’ Totten too.
My big concern about accelerating melt from Greenland isn’t sea-level rise but what that much new freshwater will mean for the Atlantic conveyor and thermohaline circulation.