The future surface mass balance (SMB) of Antarctic ice shelves has not been constrained with models of sufficient resolution and complexity. Here, we force the high‐resolution Modèle Atmosphérique Régional (MAR) with future simulations from four CMIP models to evaluate the likely effects on the SMB of warming of 1.5°C, 2°C and 4°C above pre‐industrial temperatures. We find non‐linear growth in melt and runoff which causes SMB to become less positive with more pronounced warming. Consequently, Antarctic ice shelves may be more likely to contribute indirectly to sea level rise via hydrofracturing‐induced collapse, which facilitates accelerated glacial discharge. Using runoff and melt as indicators of ice shelf stability, we find that several Antarctic ice shelves (Larsen C, Wilkins, Pine Island and Shackleton) are vulnerable to disintegration at 4°C. Limiting 21st century warming to 2°C will halve the ice shelf area susceptible to hydrofracturing‐induced collapse compared to 4°C.
Plain Language Summary
Whether Antarctic ice shelves are gaining or losing ice at the surface – their surface mass balance (SMB) – depends on many factors. To understand future Antarctic ice shelf SMB requires complex computer models, and until now, few studies using these models have been done. Here, we use the high‐resolution MAR model to explore how ice shelf SMB changes under warming scenarios of 1.5°C, 2°C and 4°C above pre‐industrial temperatures. Our results show that warming causes SMB to decrease because high temperatures produce meltwater, which then runs off the ice shelves, and that this effect is larger for greater levels of warming. Antarctic ice shelves may contribute to rising sea levels in future because larger amounts of melt and runoff increase their vulnerability to ‘hydrofracturing’, a process whereby ice shelves crack and disintegrate. Limiting future warming will reduce the number of ice shelves that will be susceptible to collapse via this mechanism.
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For plain language:
“A third of Antarctic ice shelves could collapse at current pace of warming
By Rafi Letzter - Staff Writer 7 days ago
The difference between 2 degrees and 4 degrees of warming is measured in millions of gigatons of ice.”