For decades, the ice shelf helping to hold back one of those fastest-moving glaciers in Antarctica has gradually thinned. Evaluation of satellite images shows a more dramatic process in recent yearsFrom 2017 into 2020, large icebergs in the ice shelf’s border broke off, and the glacier sped upward.
Since floating ice shelves help to hold back the bigger grounded bulk of the glacier, the current speedup as a result of weakening edge could shorten the timeline to get Pine Island Glacier’s eventual collapse into the sea. The study from investigators at the University of Washington and British Antarctic Survey was published June 11 from the open-access journal Science Advances.
“We may not have the luxury of waiting for slow changes on Pine Island; things could actually go much quicker than expected,” said lead author Ian Joughin, a glaciologist at the UW Applied Physics Laboratory. “The processes we’d been studying in this region were leading to an irreversible collapse, but at a fairly measured pace. Things could be much more abrupt if we lose the rest of that ice shelf.”
Pine Island Glacier contains approximately 180 trillion tons of ice–equivalent to 0.5 meters, or 1.6 ft, of worldwide sea level increase . It’s already responsible for a lot of Antarctica’s contribution to sea-level increase, inducing about one-sixth of a millimeter of sea level increase annually, roughly two-thirds of an inch per century, a rate that’s anticipated to rise. If it and neighboring Thwaites Glacier speed up and flow entirely into the sea, releasing their hold on the bigger West Antarctic Ice Sheet, global seas could rise by several feet over the next few centuries.
These glaciers have attracted attention in recent decades as their ice shelves thinned because warmer ocean currents pumped the ice’s bottom. From the 1990s to 2009, Pine Island Glacier’s movement toward the sea hastened from 2.5 kilometers per year to 4 kilometers each year (1.5 miles per year to 2.5 mph ). The glacier’s rate then stabilized for almost a decade.
Results show that what’s happened more recently is another procedure, Joughin explained, related to internal forces on the glacier.
From 2017 to 2020, Pine Island’s ice shelf dropped one-fifth of its place in a couple of dramatic breaks which were captured by the Copernicus Sentinel-1 satellites, operated by the European Space Agency on behalf of the European Union. The researchers analyzed graphics from January 2015 to March 2020 and found that the current modifications on the ice shelf were not due to procedures directly associated with sea melting.
“The ice shelf appears to be ripping itself apart due to the glacier’s acceleration in the past decade or two,” Joughin said.
Two points on the glacier’s surface which were examined in the paper sped upward by 12percent involving 2017 and 2020. The authors used an ice flow model developed in the UW to affirm that the loss of this ice plate caused the observed speedup.
“The recent changes in speed are not due to melt-driven thinning; instead they’re due to the loss of the outer part of the ice shelf,” Joughin said. “The glacier’s speedup is not catastrophic at this point. But if the rest of that ice shelf breaks up and goes away then this glacier could speed up quite a lot.”
It’s not clear whether the shelf will continue to crumble. Other factors, such as the incline of the land below the glacier’s receding edge, will come into play, Joughin said. However, the results change the timeline for when Pine Island’s ice shelf might vanish and how fast the glacier may move, boosting its contribution to rising seas.
“The loss of Pine Island’s ice shelf now looks like it possibly could occur in the next decade or two, as opposed to the melt-driven subsurface change playing out over 100 or more years,” stated co-author Pierre Dutrieux, an ocean physicist in British Antarctic Survey. “So it’s a potentially much more rapid and abrupt change.”
Pine Island’s ice cream is significant since it’s helping to hold this back comparatively unstable West Antarctic glacier, How the curved buttresses on Notre Dame cathedral hold