An iceberg breaks off of Pine Island Glacier's calving front. Credit: NASA ICE/flickr
The Pine Island Glacier (PIG) in West Antarctica, is a large ice stream that drains the West Antarctic Ice Sheet. It flows west-northwest along the south side of the Hudson Mountains and into the Amundsen Sea. This rapidly melting glacier accounts for 25% of the continents ice loss. The National Ice Center(NIC) has announced that a calving event has recently been observed, and is speeding up PIG'S retreat. Tthe iceberg is now known as Iceberg B35.
B-35 is located at 74°41’36” South, 103°53’12” West, in the Amundsen Sea. The iceberg measures 11 nautical miles on its longest axis and 7 nautical miles on its widest axis. Analyst Chris Readinger confirmed B-35 using the Sentinal-1 images shown below. Iceberg names are derived from the Antarctic quadrant in which they were originally sighted. The quadrants are divided counter-clockwise in the following manner: A = 0-90W (Bellingshausen/Weddell Sea) B = 90W-180 (Amundsen/Eastern Ross Sea) C = 180-90E (Western Ross Sea/Wilkesland) D = 90E-0 (Amery/Eastern Weddell Sea)Simulation showing the major glaciers of the Amundsen Sea Embayment in West Antarctica over three centuries of sustained retreat Credit: Cornford et al., The Cryosphere, 2015
Climate Central reports on the new research published in the journal The Cryosphere. Though I personally believe that SLR is not what will do us in, as a low lying coastal resident this is distressing news nonetheless.
New research published Tuesday in The Cryosphere revises how much West Antarctica could contribute to sea level rise. The findings indicate that West Antarctica could contribute an additional 8 inches of water on top of an estimated of 39 inches of sea level rise projected by the end of this century. Put another way, the region would drop the equivalent of a 19,000 cubic mile ice cube into the world’s oceans. The region will continue adding water to the world’s oceans through at least 2200, representing a major threat to coasts everywhere. snip The big glaciers — Pine Island, Thwaites and Smith Glaciers — have all been showing thinning rates much in excess of what you’d expect to see,” Stephen Cornford, an ice sheet modeler at the University of Bristol and lead author of the study, said.Ted Scambos, a lead researcher of the National Snow and Ice Data Center’s science team, likened the Thwaites Glacier to the Amazon. Both face major pressure from global warming and any change in their current state could have major ramifications for the rest of the world. In the Amazon’s case, it’s sequestering carbon while for the Thwaites, the fate of coastal communities hangs in the balance.
The Thwaites, along with other glaciers that ring West Antarctica, reach down from the main ice sheet and connect to large ice shelves that float in the seas. Warming waters are undercutting these ice shelves. In an unfortunate quirk of geology, the bedrock that the glaciers sit on is below sea level, allowing water to undermine the glaciers and ice shelves and make its way further and further inland while also speeding the flow of ice to the sea.
Cornford’s new research shows that by 2200, ground lines — the place where water meets solid ice — could retreat inland by nearly 125 miles in some areas.
Abstract from of The Cryosphere: Abstract. We use the BISICLES adaptive mesh ice sheet model to carry out one, two, and three century simulations of the fast-flowing ice streams of the West Antarctic Ice Sheet, deploying sub-kilometer resolution around the grounding line since coarser resolution results in substantial underestimation of the response. Each of the simulations begins with a geometry and velocity close to present-day observations, and evolves according to variation in meteoric ice accumulation rates and oceanic ice shelf melt rates. Future changes in accumulation and melt rates range from no change, through anomalies computed by atmosphere and ocean models driven by the E1 and A1B emissions scenarios, to spatially uniform melt rate anomalies that remove most of the ice shelves over a few centuries. We find that variation in the resulting ice dynamics is dominated by the choice of initial conditions and ice shelf melt rate and mesh resolution, although ice accumulation affects the net change in volume above flotation to a similar degree. Given sufficient melt rates, we compute grounding line retreat over hundreds of kilometers in every major ice stream, but the ocean models do not predict such melt rates outside of the Amundsen Sea Embayment until after 2100. Within the Amundsen Sea Embayment the largest single source of variability is the onset of sustained retreat in Thwaites Glacier, which can triple the rate of eustatic sea level rise.