West Antarctic Glaciers Retreating Irreversibly: Study

West Antarctic Ice Sheet Retreat Passes the Point of No Return

West Antarctic glaciers are retreating irreversibly and there is no barrier to hold them back, according to a recent study.

The Thwaites, Smith, Haynes, Pope, Smith and Kohler Glaciers and the Pine Island Glacier (PIG) have been thinning rapidly, the study says.

The warming seawater has been thinning six key glaciers from below, and they are flowing rapidly into the Amundsen Sea.

“In our new study, we present additional data that the junction of the glaciers with the ocean – the grounding line – has been retreating at record speeds unmatched anywhere in the Antarctic,” said the report’s lead author.

“We present observational evidence that a large section of the West Antarctic Ice Sheet has gone into a state of irreversible retreat; it has passed the point of no return.”

Nothing to hold the retreat back

“We also present new evidence that there is no large hill at the back of these glaciers that could create a barrier and hold the retreat back. This is why we conclude that the disappearance of ice in this sector is unstoppable,” he said.

“This retreat will have major consequences for sea level rise worldwide. It will raise sea levels by 1.2m, or 4ft, but its retreat will also influence adjacent sectors of the West Antarctic Ice Sheet which could triple this contribution to sea level.”

Title: Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith and Kohler glaciers, West Antarctica from 1992 to 2011.

Abstract

We measure the grounding line retreat of glaciers draining the Amundsen Sea Embayment of West Antarctica using Earth Remote Sensing (ERS-1/2) satellite radar interferometry from 1992 to 2011. Pine Island Glacier retreated 31 km at its center, with most retreat in 2005–2009 when the glacier un-grounded from its ice plain. Thwaites Glacier retreated 14 km along its fast-flow core and 1 to 9 km along the sides. Haynes Glacier retreated 10 km along its flanks. Smith/Kohler glaciers retreated the most, 35 km along its ice plain, and its ice shelf pinning points are vanishing. These rapid retreats proceed along regions of retrograde bed elevation mapped at a high spatial resolution using a mass conservation technique (MC) that removes residual ambiguities from prior mappings. Upstream of the 2011 grounding line positions, we find no major bed obstacle that would prevent the glaciers from further retreat and draw down the entire basin.

E. Rignot, doi: 10.1002/2014GL060140