A study by Copernicus reports that the effect of sea ice (fast land-bound ice) as a supporting force against land ice is negligible. The study area was the Larsen B ice shelf, which has been collapsing since 2002 and is effectively gone after a major collapse in 2022.
We observe the evacuation of 11-year-old sea ice in the Larsen B region of the East Antarctic Peninsula in January 2022, which was caused in part by warm atmospheric conditions and strong offshore winds. This evacuation of sea ice was closely followed by major changes in the calving behavior and dynamics of a subset of ocean-terminating glaciers in the region. We show using satellite measurements that, after a decade of gradual deceleration, the Hektoria, Green, and Crane glaciers accelerated by roughly 20%–50% between February and late 2022, each increasing in speed by more than 100 me-1. Circumstantially, this is attributed to their transition to tidal glaciers after the loss of their ice shelves following sea ice evacuation. However, it remains a question whether the land-based sea ice may have influenced the dynamics of these glaciers, or the stability of their ice shelves, through a similar buttressing effect to that of closed ice shelves on flows. ice based. We show, with a series of diagnostic modeling experiments, that direct support of sea ice had a negligible impact on the dynamics of grounded ice flows. Furthermore, we suggest that the loss of sea ice support may have affected the dynamics of rheologically weak ice shelves, reducing their stability over time; however, the accompanying shifts in the distribution of resistive stress within the ice shelves would have been small. This indicates that this loss of sea ice support on land was likely a secondary process in the breakup of the ice shelf compared to, for example, increased ocean swell or the driver of the initial sea ice breakup.
The 2002 split.
In the Southern Hemisphere summer of 2002, scientists monitoring daily satellite images of the Antarctic Peninsula watched in amazement as nearly the entire Larsen B Ice Shelf broke up and collapsed in little more than a month. They had never seen such a large area—3,250 square kilometers or 1,250 square miles—disintegrate so quickly.
2022 split.
Scientists are still investigating the reason for the split, but the early clearing of seasonal sea ice along the Antarctic Peninsula suggests that the austral summer has been warm and wet. Scientist Rajashree Tri Datta from the University of Colorado, Boulder, pointed this out the foehn winds, influenced by a large atmospheric river, helped destabilize the ice pack. The phenomenon is evident in this animation compiled with images from NOAA’s GEOS-16 satellite.
Artificial intelligence research from the University of Cambridge has for the first time mapped slush on the surface of Antarctic ice shelves. This is another threat to the Antarctic continent. This time, the damage is to the ice sheet instead of large chunks of decay from the underside of the massive ice shelves around Antarctica. Using NASA satellite imagery, it was determined that meltwater lakes and sloughs are a threat due to their weight, and surface meltwater has the potential to cause hydrofracturing and collapse.
Sleet – water-soaked snow – accounts for more than half of all meltwater on Antarctic ice shelves during peak summer, yet it is poorly accounted for in regional climate models.
Researchers led by the University of Cambridge used artificial intelligence techniques to map slush on Antarctic ice shelves and found that 57% of all meltwater is held as slush, with the remainder in surface ponds and lakes.
As the climate warms, more meltwater forms on the surface of the ice shelves, the floating ice that surrounds Antarctica, which acts as a buffer against glacier ice from the interior. Increased meltwater can lead to ice shelf instability or collapse, which in turn leads to sea level rise.
The researchers also found that the sludgy and accumulated meltwater leads to 2.8 times more meltwater formation than predicted by standard climate models, as it absorbs more heat from the sun than ice or snow. of resultsreported in the journal Nature Geosciencecould have profound implications for ice shelf stability and sea level rise.
PIECES
“Since the slush is stiffer than meltwater, it won’t cause hydrofracturing in the same way as water from a lake, but it’s definitely something to consider when trying to predict how or if ice shelves will collapse ,” Willis said.
In addition to the potential implications of mud on hydrofracturing, it also has a major effect on melting rates. Since slush and lakes are less white than snow or ice, they absorb more heat from the sun, causing more snow to melt. This additional melting is not currently accounted for in climate models, which may lead to underestimates in predictions of ice sheet melting and ice shelf stability.
The study can be found in Nature Geoscience.
Bob Berwyn writes in Inside Climate News:
Earlier this week, a separate study in the same journal also showed the increasing susceptibility of Antarctic ice shelves to melting from below, with findings suggesting that a warming ocean is likely to lead to “runaway melting”.
Thwaites Glacier damage continues deep into winter. In the Amundsen Sea basin, year-round melting is occurring in the presence of open water.
For further reading:
Damage to the ice tongue of Astrolabe Glacier (Adélie Coast, Antarctica).
Surface dynamics and calving cycle history of AstrolabeGlacier (Adélie Coast, Antarctica) derived from satellite images
By Daily Kos blogger Denise Oliver Velez.
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