Sea ice could control Antarctic ice sheet stability, New Research Findings – Boosted by that?
UNIVERSITY OF CAMBRIDGE
CREDIT: FRAZER CHRISTIE
Despite the rapid melting of ice in many parts of Antarctica in the second half of the 20sorder Researchers have found that the ice shelves that cover the eastern Antarctic peninsula have undergone sustained development over the past 20 years.
Ice shelves – floating pieces of ice attached to land-based ice sheets – serve the important purpose of combating the uncontrolled release of ice from land to ocean. In the last 20 yearsorder century, high levels of warming east of the Antarctic peninsula led to the catastrophic collapse of the Larsen A and B ice shelves in 1995 and 2002 respectively. These events spurred the acceleration of the ice toward the ocean, ultimately accelerating the Antarctic Peninsula’s contribution to sea level rise.
Currently, the jury is out on how exactly the sea ice around Antarctica will evolve in response to climate change and thus affect sea level rise, with several models predicting how much Sea ice is completely lost in the Southern Ocean, while other models predict an increase in sea ice.
Now, an international team of researchers, from the Universities of Cambridge and Newcastle in the United Kingdom, and the University of Canterbury in New Zealand, have used a combination of historical satellite measurements, along with records of oceans and atmosphere, to get the most detailed understanding of how ice conditions are changing along the 1,400-kilometer Antarctic Peninsula.
They found that 85% of the circumference of the ice shelf in this part of Antarctica has increased since the early 2000s, in contrast to the sweeping retreat of the previous two decades. This advance is related to decade-scale changes in atmospheric circulation, resulting in more sea ice being carried by winds to the coast.
The resultsreported in the journal Natural Geosciencesshowed that sea ice plays an important role in stabilizing ice shelves, just as ice shelves self-stabilize and play a role in fixing ice sheets.
Dr Frazer Christie from Cambridge’s Polar Research Institute (SPRI), lead author of the paper, said: “We have found that sea ice changes can either protect or initiate movement, creates icebergs from the large Antarctic ice shelves. “Regardless of how sea ice around Antarctica changes in a warming climate, our observations highlight the often overlooked importance of sea ice variability for the health of the Southern Ice Sheet. Pole.”
In 2019, Christie and his co-authors were part of an expedition led by SPRI to study ice conditions in the Weddell Sea off the east coast of the Antarctic Peninsula, a part known to be difficult to access. of the Southern Ocean with a year-round dense presence of sea ice.
“During the expedition, we noted that portions of the ice shelf coastline are at their most advanced since satellite records began in the early 1960s,” said the expedition’s lead scientist and co-author. study author, Professor Julian Dowdeswell, also from SPRI, said.
Following the expedition, the team used 60-year retrograde satellite images, as well as modern ocean and atmospheric models, to investigate in detail the spatial and temporal pattern of changes of the shelf. ice.
So what caused the ice shelves to move forward? In the absence of atmosphere and ocean warming over the past 20 years, the dominant control was found to be a shift in regional wind patterns over the Weddell Sea, which has the effect of pushing up sea ice. ice shelves.
In contrast, between 1985 and 2002, wind conditions in the same area caused sea ice to move away from the coast. By removing the quenching effect of sea ice and exposing the ice shelves to damaging ocean waves, stress on the ice shelves increases, which eventually leads to the formation of icebergs.
In most cases throughout the satellite era, spawning from the ice shelves east of the Antarctic Peninsula occurred only during or shortly after the removal of sea ice in some form.
However, it is possible that this pre-ice age may be over. Since 2020, there has been a significant increase in the number of icebergs coming out of the eastern Antarctic peninsula. Co-author Dr Wolfgang Rack from the University of Canterbury, said: “It is entirely possible that we see a transition back to atmospheric patterns similar to those observed in the 1990s, encouraging sea ice loss and ultimately more spawning in the ice shelf. .
Work made possible by the free, open access of historical satellite records of space agencies and partners including NASA and the Joint European Commission – European Space Agency Copernicus Program .
The research was supported in part by the Flotilla Foundation, the Swiss Marine Archeology Consulting Company and the Prince Albert II Foundation of Monaco.
JOURNEYS
Natural Geosciences
DOI
ARTICLE TITLE
Evolution of the Antarctic ice shelf due to anomalous atmospheric circulation and sea ice
ARTICLE PUBLICATION DATE
May 5, 2022
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