Understanding extreme weather risks to ice-sheet stability as a potential climate tipping point

Record-shattering climate extremes are becoming a seemingly everyday reality across the globe as anthropogenic climate change accelerates. Over polar regions, similar weather extremes receive less attention, but are responsible for a recent pause and slight reversal of Antarctic ice loss since 2020 and ultimately mitigating global sea-level rise. In March 2022, one particularly extreme weather event in the form of an atmospheric river (AR) caused enough snowfall in East Antarctica to help make 2022 a positive mass year for Antarctica. Yet, this same event caused a heatwave that led to the highest temperature anomaly ever recorded globally (39° C) and triggered the final collapse of the Conger ice shelf simultaneously demonstrating the opposing yet significant effects of extreme weather on the Antarctic mass balance.

While the gradual thinning and grounding line retreat of ice shelves through ocean basal melting pushes ice shelves towards non-viability and collapse in a bifurcation-induced tipping point, extreme weather may trigger that collapse sooner through noise-induced tipping. However, short-medium term (10-50 years) increases in extreme snowfall events may mitigate  ice loss more strongly than currently observed. Thus, to constrain future sea-level rise projections, the potential impacts from extreme weather in the short-medium term must be considered.

The uncertainty in predicting the influence of extreme weather on ice shelf stability is partly due to our limited ability to simulate many of the smaller scale processes and impacts that are essential to fully explain polar extreme weather in the present day combined with a limited understanding of how future changes in extreme weather patterns will influence ice sheet dynamics. Global climate models generally lack the spatial resolution to capture small-scale extreme weather processes, and evaluating their impact on ice sheet dynamics requires coupling to ice sheet models that is currently undeveloped.  

In this talk, I will present the role of extreme weather in influencing the Antarctic mass balance and how extreme weather represents a potential climate tipping point for ice shelf stability. This will involve discussing the current state of Antarctic extreme weather research along with the uncertainties and research gaps in determining the extreme weather risk to ice shelf stability.