Copernican research The impact of sea ice (fast ice connected to land) on the support of land ice is reported to be negligible. The study area is the Larsen B Ice Shelf, which has been collapsing since 2002 and is virtually gone after a major collapse in 2022.
In January 2022, we observed the disappearance of 11-year-old sea ice in Larsen B Bay, East Antarctic Peninsula, which was partially caused by warmer atmospheric conditions and strong offshore winds. This sea ice loss was immediately followed by significant changes in the calving behavior and dynamics of some of the marine-terminating glaciers in the region. Using satellite measurements, we show that after a decade of gradual deceleration, Hectoria, Green and Klein Glaciers accelerated by approximately 20%-50% from February to the end of 2022, with each increasing by more than 10%. 100 Ma−1Contextually, this is due to the loss of ice shelves and their transition to tidewater glaciers after removal of fixed sea ice. However, questions remain as to whether fixed sea ice could have influenced the dynamics of these glaciers and the stability of the ice shelves through a similar bracing effect as trapped ice shelves on the accretion stream. A series of diagnostic modelling experiments show that direct bracing of fixed sea ice had little effect on the dynamics of the accretion stream. Furthermore, we suggest that the loss of bracing of fixed sea ice may have influenced the dynamics of the rheologically weak ice shelves, reducing their stability over time, although the associated changes in the distribution of drag stresses within the ice shelves would have been minor. This indicates that the loss of bracing by fixed sea ice was likely a secondary process in the collapse of the ice shelves, compared to, for example, increased ocean swell and other drivers of the initial accretion of fixed sea ice.
During the austral summer of 2002, scientists monitoring daily satellite images of the Antarctic Peninsula watched in amazement as almost the entire Larsen B Ice Shelf calved and broke apart in just over a month. They had never seen such a large area – 3,250 square kilometers (1,250 square miles) – break up so quickly.
Scientists are still investigating what caused the melt, but the early loss of seasonal sea ice along the Antarctic Peninsula suggests that the Southern Hemisphere had a warmer, wetter summer, said Rajashree Tri Dutta, a scientist at the University of Colorado Boulder. Föhn windThis phenomenon, influenced by large atmospheric rivers, contributed to the destabilization of the ice sheet. This animation Created with imagery from NOAA’s GEOS-16 satellite.
From AI research University of Cambridge Meltwater on the surface of the Antarctic ice shelf has been mapped for the first time, another threat to the Antarctic continent. This time, instead of widespread collapse of the lower parts of the huge ice sheet around Antarctica, the ice sheet is being affected. Using NASA satellite imagery, it was found that meltwater lakes and meltwater are a threat due to their weight, and that meltwater on the surface could cause hydraulic fracturing and collapse.
Slush (water-soaked snow) makes up more than half of the meltwater on Antarctic ice shelves in midsummer, but is not adequately accounted for in regional climate models.
Researchers led by the University of Cambridge used artificial intelligence techniques to map the meltwater distribution on Antarctic ice shelves and found that 57% of all meltwater is stored as meltwater, with the rest pooling in surface ponds and lakes.
A warmer climate produces more meltwater on the surface of the floating ice surrounding Antarctica, providing support for glacial ice from inland. Increased meltwater can lead to ice shelf instability and collapse, which in turn contributes to sea level rise.
The researchers also found that muddy water and trapped meltwater absorb more heat from the sun than ice or snow, leading to 2.8 times more meltwater formation than predicted by standard climate models. resultReported in the journal Nature Chemistrycould have significant effects on ice shelf stability and sea level rise.
Cut into small pieces
“Muddy water is more solid than meltwater and therefore won’t cause hydraulic fracturing the way lake water does, but it definitely needs to be taken into account when predicting whether or how the ice shelf will break up,” Willis said.
As well as their potential impact on hydraulic fracturing, muds also have a large effect on melting rates. Because muds and lakes are less white than snow and ice, they absorb more heat from the sun, accelerating melting. This extra melting is not currently accounted for in climate models, which can lead to underestimation of predictions of ice sheet melt and ice shelf stability.
This study Nature Geoscience.
Bob Berwin writes: Inside Climate News:
Earlier this week, Another study The journal paper also shows that Antarctic ice shelves are increasingly vulnerable to melting from below, and their findings suggest that ocean warming is likely to lead to “runaway melting.”
The damage to Thwaites Glacier continues into the middle of winter: in the Amundsen Sea Bay, the glacier melts all year round, despite being open water.
Further info:
Damage to the ice tongue of Astrolabe Glacier (Adelie Coast, Antarctica).
By Daily Kos blogger Denise Oliver Velez.
