Melting Ice Shelves

Iceberg B09B & Cape Denison - 23 May 2016, Antarctica (by OVERVIEW based pm Observational Data courtesy of Landsat 8 satellite (Bands: 2, 3, 4, 8) & USGS processed by Paul Quast, CC BY 2.0 DEED via Flickr).

“Together, the Antarctic and Greenland Ice Sheets contain more than 99 percent of freshwater ice on Earth. If they both completely melted, they would raise sea level by an estimated 67.4 meters (223 feet). Long-term satellite data indicate that through most of the twentieth century, the ice sheets made very little contribution to sea level, and were nearly in balance in annual snowfall gain and ice or meltwater loss. However, the stability of the ice sheets has changed considerably in the twenty-first century…”

–  Ice Sheets Today

“It appears we may have lost control of the West Antarctic ice shelf melting over the 21st century,” Kaitlin Naughten, the study’s lead author and an ocean modeler with the British Antarctic Survey, told reporters in a media briefing. “That very likely means some amount of sea level rise that we cannot avoid.”
– the Washington Post (10-23-2023)

“It got a lot harder to be a glacier in Greenland in the 21st century than it had been even in the 1990s,” said Yarrow Axford, a professor of geological sciences at Northwestern University and a co-author of the paper, published in the journal Nature Climate Change.
– the New York Times (10-23-2023)

Recently Published Research Findings:

Rapid disintegration and weakening of ice shelves in North Greenland
 – nature communications (11-07-2023)

ABSTRACT: The glaciers of North Greenland are hosting enough ice to raise sea level by 2.1 m, and have long considered to be stable. This part of Greenland is buttressed by the last remaining ice shelves of the ice sheet. Here, we show that since 1978, ice shelves in North Greenland have lost more than 35% of their total volume, three of them collapsing completely. For the floating ice shelves that remain we observe a widespread increase in ice shelf mass losses, that are dominated by enhanced basal melting rates. Between 2000 and 2020, there was a widespread increase in basal melt rates that closely follows a rise in the ocean temperature. These glaciers are showing a direct dynamical response to ice shelf changes with retreating grounding lines and increased ice discharge. These results suggest that, under future projections of ocean thermal forcing, basal melting rates will continue to rise or remain at high level, which may have dramatic consequences for the stability of Greenlandic glaciers.

Unavoidable future increase in West Antarctic ice-shelf melting over the twenty-first century
 – nature climate change (10-23-2023)

ABSTRACT: Ocean-driven melting of floating ice-shelves in the Amundsen Sea is currently the main process controlling Antarctica’s contribution to sea-level rise. Using a regional ocean model, we present a comprehensive suite of future projections of ice-shelf melting in the Amundsen Sea. We find that rapid ocean warming, at approximately triple the historical rate, is likely committed over the twenty-first century, with widespread increases in ice-shelf melting, including in regions crucial for ice-sheet stability. When internal climate variability is considered, there is no significant difference between mid-range emissions scenarios and the most ambitious targets of the Paris Agreement. These results suggest that mitigation of greenhouse gases now has limited power to prevent ocean warming that could lead to the collapse of the West Antarctic Ice Sheet.

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