Massive Antarctic glacier accelerating toward the sea as key ice shelf is ripping apart

The Pine Island Glacier's ice shelf in Antarctica is ripping itself apart, which is likely to accelerate the advance of the massive glacier into the ocean, resulting in a more rapid global sea-level rise.

The Pine Island Glacier's ice shelf lost about one-fifth of its area from 2017 to 2020, mostly due to three major breaks. These breaks allowed the glacier to speed up its downward motion toward the coast by 12 percent, which has further added to its contribution to rising sea levels.

From the 1990s to 2009 the glacier's motion toward the sea accelerated from 2.5 to 4 kilometers per year before stabilizing again.

If melted out completely, the Pine Island Glacier would contribute about 1.6 feet to the global sea level.

In the past, most of this acceleration was induced by warmer ocean currents melting the underside of the glacier. Recent data suggests that from 2015 to 2020 the primary cause of the acceleration toward the sea was due to the ice shelf (which holds the glacier back from the sea) basically ripping itself apart.

Key excerpts from the University of Washington News......

“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,” said lead author Ian Joughin, a glaciologist at the UW Applied Physics Laboratory. “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.”

“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,” said co-author Pierre Dutrieux, an ocean physicist at British Antarctic Survey. “So it’s a potentially much more rapid and abrupt change.”