Getz Ice Shelf of the Amundsen Sector, West Antarctica, and sea ice offshore. Credit: NASA/USGS, processed by Dr. Frazer Christie, Scott Polar Research Institute, University of Cambridge
Runaway West Antarctic ice retreat can be slowed by climate-driven changes in ocean temperature.
New research discovers that ice-sheet-wide collapse in West Antarctica isnt unavoidable: the rate of ice loss varies according to regional distinctions in environment and ocean circulation.
An international team of researchers has actually combined satellite imagery and climate and ocean records to obtain the most detailed understanding yet of how the West Antarctic Ice Sheet– which includes enough ice to raise worldwide water level by 3.3 meters– is reacting to climate change.
What triggered these weaker winds and, by implication, decreased ice melt? The researchers discovered the main cause was an unusual deepening of the Amundsen Sea Low pressure system, which led to less warm water intrusion. This system is the crucial climatic flow pattern in the region, and its pressure center location– near which modifications in offshore wind strength are biggest– generally sits offshore of its name coast for most of the year.
” Ocean and climatic forcing systems still truly, actually matter in West Antarctica,” said co-author Professor Eric Steig from the University of Washington in Seattle. It depends on how environment modifications over the next couple of decades, which we might affect in a favorable method by lowering greenhouse gas emissions.”
The scientists, from the University of Cambridge, the University of Edinburgh, and the University of Washington, discovered that the speed and level of ice destabilization along West Antarcticas coast varies according to differences in local environment.
Their results, reported today (January 16, 2023) in the journal Nature Communications, reveal that while the West Antarctic Ice Sheet continues to pull away, the pace of retreat slowed across a susceptible region of the shoreline in between 2003 and 2015. This slowdown was driven by modifications in surrounding ocean temperature level, which were in turn triggered by variations in offshore wind conditions.
Sentinel-1 image composite depicting Land Glacier and its sea-ice-encased ice tongue, West Antarctica. Credit: Copernicus EU/ESA, processed by Dr. Frazer Christie, Scott Polar Research Institute, University of Cambridge
The marine-based West Antarctic Ice Sheet, home to the unsteady and huge Pine Island and Thwaites glaciers, sits atop a landmass lying approximately 2,500 meters listed below the surface of the ocean. Given that the early 1990s, researchers have observed an abrupt acceleration in ice melting, retreat, and speed in this location, which is associated in part to human-induced climate change over the past century.
Other researchers have actually previously shown that this type of action throughout a low-lying landmass might be the start of a permanent, ice-sheet-wide collapse called a marine ice sheet instability, which would continue independently of any further climatic impact.
” The concept that as soon as a marine-based ice sheet passes a certain tipping point it will cause a runaway response has been extensively reported,” stated Dr. Frazer Christie from Cambridges Scott Polar Research Institute, the papers lead author. “Despite this, questions stay about the extent to which continuous modifications in climate still manage ice losses along the entire West Antarctic coastline.”
Using observations collected by a variety of satellites, Christie and colleagues discovered pronounced regional variations in how the West Antarctic Ice Sheet has evolved because 2003 due to climate change, with the pace of retreat in the Amundsen Sea Sector having slowed considerably in contrast to the much and neighboring accelerated Bellingshausen Sea Sector.
By examining environment and ocean records, the researchers linked these regional differences to changes in the strength and direction of offshore surface area winds.
Sentinel-1 image dated January 10th, 2023 showing the highly dynamic Amundsen Sea Embayment area, West Antarctica. Credit: Copernicus EU/ESA, processed by Dr. Frazer Christie, Scott Polar Research Institute, University of Cambridge
In this part of Antarctica, the prevailing winds come from the west. When these westerly winds get stronger, they stir up warmer, saltier water from deep in the ocean, which reaches the Antarctic shoreline and increases the rate of ice melt.
” But between 2003 and 2015 overseas of the Amundsen Sea Sector, the strength of the prevailing westerly winds lowered,” stated Christie. “This suggested that the much deeper, warmer water couldnt intrude, and we saw a notable change in matching glacier behavior along the region: a clear reduction in the rate of melt and ice-mass loss.”
What triggered these weaker winds and, by implication, reduced ice melt? The scientists found the main cause was an unusual deepening of the Amundsen Sea Low pressure system, which led to less warm water intrusion. This system is the crucial atmospheric circulation pattern in the area, and its pressure center location– near which modifications in overseas wind strength are biggest– typically sits offshore of its name coast for the majority of the year.
Farther afield from this pressure center, the researchers found that the faster response of the glaciers streaming from the Bellingshausen Sea Sector can be explained by reasonably more unchanged winds, making it possible for more relentless ocean-driven melt by contrast.
Eventually, the research study illustrates the intricacy of the contending ocean, environment, and ice interactions driving short-term changes across West Antarctica, and raises crucial concerns about how rapidly the icy continent will progress in a warming world.
” Ocean and atmospheric forcing systems still truly, truly matter in West Antarctica,” stated co-author Professor Eric Steig from the University of Washington in Seattle. “That indicates that ice-sheet collapse is not inescapable. It depends upon how environment changes over the next couple of decades, which we might influence in a favorable method by decreasing greenhouse gas emissions.”
The researchers stress that further work is required to take a look at how crucial such mechanisms will be in the future amid a background of increasing marine ice sheet instability. Co-author Professor Robert Bingham from the University of Edinburgh is now working straight on Thwaites Glacier to comprehend how it is being affected by environment change.
” This research study enhances the immediate requirement to clarify how rapidly the most susceptible areas of the West Antarctic Ice Sheet such as Thwaites Glacier will pull back, with global effects for water level increase,” said Bingham. “New information that we are presently obtaining from a traverse throughout Thwaites Glacier this January will directly resolve this objective.”
” There is an intimate link between the climate and how the ice is acting,” said Christie. “We have the capability to reduce West Antarctic ice losses– if we curb carbon emissions.”
Reference: “Inter-decadal environment irregularity induces differential ice response along Pacific-facing West Antarctica” 16 January 2023, Nature Communications.DOI: 10.1038/ s41467-022-35471-3.
The study was supported by the Carnegie Trust for the Universities of Scotland, the Scottish Alliance for Geoscience, Environment and Society (SAGES), the Prince Albert II of Monaco Foundation, the Natural Environment Research Council (NERC), part of UK Research and Innovation (UKRI), the United States National Science Foundation, the joint UK NERC/US NSF International Thwaites Glacier Collaboration task and the European Space Agency (ESA).