  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.
