Abstract
AbstractThe 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 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.
Highlights
The collapse, thinning, or recession of Antarctic ice shelves influences sea level rise by reducing shelf buttressing and allowing tributary glaciers to accelerate, increasing ice discharge into the ocean (Borstad, 2013; Fürst et al, 2016; Lai et al, 2020; Rignot et al, 2004; Trusel et al, 2015)
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
Our results show that warming causes surface mass balance (SMB) to decrease because high temperatures produce meltwater, which runs off the ice shelves, and that this effect is larger for greater levels of warming
Summary
The collapse, thinning, or recession of Antarctic ice shelves influences sea level rise by reducing shelf buttressing and allowing tributary glaciers to accelerate, increasing ice discharge into the ocean (Borstad, 2013; Fürst et al, 2016; Lai et al, 2020; Rignot et al, 2004; Trusel et al, 2015). Present mass loss from Antarctic ice shelves is primarily related to ice and ocean dynamical changes caused by iceberg calving and basal melting, respectively (Shepherd et al, 2018), surface processes such as melt are useful indicators of ice shelf stability and their likely contribution to sea level rise because of the importance of surface processes in driving ice shelf fracture and collapse (Bell et al, 2018; Kingslake et al, 2017). Ice shelves saturated with refrozen meltwater are susceptible to collapse, such as occurred on the Antarctic Peninsula (Kuipers Munneke et al, 2018; Scambos et al, 2000, 2003; van den Broeke, 2005) This means runoff can be used as an indicator of shelf stability because runoff occurs only when meltwater cannot refreeze in the snowpack, implying that hydrofracturing is possible. Constraining the response of Antarctic ice shelves under warming scenarios of 1.5°C, 2°C, and 4°C will improve understanding of the likely impact of future warming on Antarctic mass loss and sea level rise
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