Sea level rise projections from storylines of Antarctic ice shelf collapse and its implication for adaptive planning in the Netherlands

Abstract

In this study we model the dynamic sea level rise that results when Antarctica losses a substantial part of its buttressing ice shelves. To assess the timing of this loss, we perform a separate stability analysis that incorporates both oceanic and atmospheric forcings. We conclude that both the magnitude and the timing of larger scale sea level rise from Antarctic ice shelf collapse is principally controlled by the ocean-induced thinning but that atmospheric forcings have the ability to slightly expedite the moment of collapse. We further assess that larger scale ice shelf collapse is unlikely before the early second half of the 21st century, and that the resultant dynamic sea level rise will become important in the mid- to late second half of this same century. We find that the uncertainty caused by the variation between the ice sheet models is more than twice as large as the uncertainty caused by the triggers for ice shelf collapse. These findings suggest that if we want to better curtail the sea level rise uncertainty from a large dynamic contribution of the Antarctic Ice Sheet, curbing - or at least attributing - variations between ice sheet models is more important than the development of better predictions for the sub-shelf melting. We confirm that a long-term perspective on sea level rise can help policy makers to overcome decision paralysis on the short- to mid-term. Indeed, when Antarctic ice shelf collapse becomes a distinct possibility, it is likely not a matter of if and how to adapt to certain levels of sea level rise, but when to adapt. Flexible measures with a short lead- and lifetime can play a role in the adaptive strategy, but are inferior to larger measures for an extreme sea level rise scenario like the one considered here, or when taking on a long-term perspective.