Sea-level projections representing deeply uncertain ice-sheet contributions

TL;DR

This paper presents probabilistic sea-level rise projections that account for deeply uncertain Antarctic ice sheet contributions, highlighting their potential dominance in future sea-level rise and the need for robust adaptive strategies.

Contribution

It introduces a set of probabilistic projections that incorporate deeply uncertain Antarctic ice sheet behavior, emphasizing the importance of considering these uncertainties in decision-making.

Findings

Deep uncertainties in Antarctic ice sheet contributions can dominate sea-level rise projections within decades.

Projections show high sensitivity to controversial assumptions about ice sheet stability.

Robust adaptive strategies are necessary to manage the risks posed by these uncertainties.

Abstract

Future sea-level rise poses nontrivial risks for many coastal communities. Managing these risks often relies on consensus projections like those provided by the IPCC. Yet, there is a growing awareness that the surrounding uncertainties may be much larger than typically perceived. Recently published sea-level projections appear widely divergent and highly sensitive to non-trivial model choices and the West Antarctic Ice Sheet (WAIS) may be much less stable than previously believed, enabling a rapid disintegration. In response, some agencies have already announced to update their projections accordingly. Here, we present a set of probabilistic sea-level projections that approximate deeply uncertain WAIS contributions. The projections aim to inform robust decisions by clarifying the sensitivity to non-trivial or controversial assumptions. We show that the deeply uncertain WAIS contribution can dominate other uncertainties within decades. These deep uncertainties call for the development of robust adaptive strategies. These decision-making needs, in turn, require mission-oriented basic science, for example about potential signposts and the maximum rate of WAIS induced sea-level changes.