Runaway West Antarctic ice retreat can be slowed by climate-driven changes in ocean temperature

So what caused these weaker winds and, by implication, reduced ice melt? The researchers found the primary cause was an unusual deepening of the Amundsen Sea Low pressure system, which led to less warm water intrusion. This system is the key atmospheric circulation pattern in the region, and its pressure centre location - near which changes in offshore wind strength are greatest - typically sits offshore of its namesake coast for most of the year.

Farther afield from this pressure centre, the researchers found that the accelerated response of the glaciers flowing from the Bellingshausen Sea Sector can be explained by relatively more unaltered winds, enabling more persistent ocean-driven melt by comparison.

Ultimately, the study illustrates the complexity of the competing ice, ocean and atmosphere interactions driving short-term changes across West Antarctica, and raises important questions about how quickly the icy continent will evolve in a warming world.

"Ocean and atmospheric forcing mechanisms still really, really matter in West Antarctica," said co-author Professor Eric Steig from the University of Washington in Seattle. "That means that ice-sheet collapse is not inevitable. It depends on how climate changes over the next few decades, which we could influence in a positive way by reducing greenhouse gas emissions."

The researchers stress that further work is needed to examine how important 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 directly on Thwaites Glacier to understand how it is being affected by climate change.

"This study reinforces the urgent requirement to clarify how rapidly the most vulnerable regions of the West Antarctic Ice Sheet such as Thwaites Glacier will retreat, with global consequences for sea level rise," said Bingham. "New data that we are currently acquiring from a traverse across Thwaites Glacier this January will directly address this goal."

"There is an intimate link between the climate and how the ice is behaving," said Christie. "We have the ability to mitigate West Antarctic ice losses - if we curb carbon emissions."

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 US National Science Foundation, the joint UK NERC/US NSF International Thwaites Glacier Collaboration project and the European Space Agency (ESA). Frazer Christie is a Postdoctoral Associate at Jesus College, Cambridge.

Reference:
Frazer D. W. Christie et al. 'Inter-decadal climate variability induces differential ice response along Pacific-facing West Antarctica.' Nature Communications (2023), doi:10.1038/s41467-022-35471-3

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