Media release
From: Springer NatureClimate change: Future melting of West Antarctic Ice Sheet may be unavoidable (N&V) *PRESS BRIEFING*
Future increases in ice-shelf melting in the West Antarctic over the twenty-first century may be unavoidable, a modelling study published in Nature Climate Change suggests. The findings suggest that rapid ocean warming in West Antarctica is already committed under a range of emission pathways, and mitigation efforts may only prevent the worst-case scenarios.
Ice shelves play an important role in buttressing, or slowing the flow of glaciers to the sea. The West Antarctic Ice Sheet is Antarctica’s largest contributor to sea-level rise. The ice loss is driven by interactions with the Southern Ocean, particularly in the Amundsen Sea. Data on warming in the Amundsen Sea are limited and while it has been proposed that the region will benefit from reductions in emissions, this has not been examined in detail.
Kaitlin Naughten and colleagues use a regional ocean model to understand future changes under different emissions scenarios in ocean heat and therefore ocean-driven ice-shelf melt in the Amundsen Sea, Antarctica. They find that even under a range of mitigation scenarios (including Paris Agreement 1.5 °C, Paris Agreement 2 °C and Representative Concentration Pathway (RCP) 4.5), climate change could cause the ocean to warm at three times the historical rate. They suggest this indicates that mitigation efforts may have limited power to slow ocean warming in the Amundsen Sea in the coming decades. They note that natural internal climate variability will also play a role in controlling the amount of warming caused by climate change. The authors project increased melt in areas crucial for buttressing the ice sheet and maintaining stability, with warming concentrated at an intermediate (200–700 m) depth that accesses the ice-shelf cavities, and leads to melt.
The authors acknowledge that this work is based on outputs from a single ice–ocean model. They note that mass loss from the West Antarctic Ice Sheet is just one component of sea-level rise, and other regions of Antarctica are unlikely to lose substantial mass if current emissions targets are met. Since the ice sheet will take centuries or millennia to fully respond to climate change, the choice of emissions scenario could have a larger impact farther in the future, beyond the 21st century, the authors conclude.
In an accompanying News & Views article, Taimoor Sohail writes, “This study by Naughten et al. represents the most comprehensive set of future projections of warming in the Amundsen Sea so far. While the window to prevent ice-shelf melting in the West Antarctic is likely to have passed, the true impacts of climate change on sea level will depend on a variety of factors.”
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