Antarctica’s Pine Island Glacier Faces Irreversible Retreat

Lee Rannals for redOrbit.com – Your Universe Online

Antarctica’s Pine Island Glacier (PIG) is now in an irreversible retreat, according to a study published in the journal Nature Climate Change. PIG is one of the biggest single contributors to global sea-level rise, and the latest study says that it could add as much as 0.39-inches to ocean levels in 20 years.

“Over the past 40 years Pine Island Glacier in West Antarctica has thinned at an accelerating rate, so that at present it is the largest single contributor to sea-level rise in Antarctica,” the authors wrote.

PIG is responsible for 20 percent of the total ice discharge from the West Antarctic Ice Sheet. The accelerated thinning observed since the 1980s has been attributed to enhanced sub-ice-shelf melting induced by Circumpolar Deep Water circulation.

The researchers used three different computer models to forecast the glacier’s future based on the ‘grounding line,’ which is the area under water where the ice shelf meets land. This line has receded by 6 miles over the past decade and is heading towards an unstable 24 mile retreat, according to the study.

“At present, the grounding line is crossing a retrograde bedrock slope that lies well below sea level, raising the possibility that the glacier is susceptible to the marine ice-sheet instability mechanism,” the researchers wrote.

Dr Hilmar Gudmundsson from the British Antarctic Survey (BAS) said to think of PIG like a ball that has been kicked and is just going to keep rolling down a hill for the foreseeable future.

“Even if you were to reduce melt rates, you would not stop the retreat,” Gudmundsson told BBC News. “We did a number of model runs where we allowed PIG to retreat some distance back, and then we lowered the melt rates in our models. And despite doing that, the grounding line continued to retreat.”

The European Space Agency (ESA) said last month that the amount of ice loss in West Antarctica is taking place at a faster pace than previously thought. Researchers used data from ESA’s CryoSat mission to show that the ice sheet in this region of Antarctica is losing nearly 100 cubic miles of ice yearly.

Continued climate change means that coastal cities could be facing dangerously high sea levels in the coming decades. The United Nations’ climate science body, the Intergovernmental Panel on Climate Change, predicted last year that sea levels would rise between 11 and 33 inches by 2100. More than 99 percent of the Earth’s glacier ice is within the Antarctic and Greenland ice sheets, so if both of these were to melt completely then it would raise the ocean levels by more than 200 feet.