Brief communication: A roadmap towards credible projections of ice sheet contribution to sea-level

Abstract. Accurately projecting mass loss from ice sheets is of critical societal importance. However, despite recent improvements in ice sheet models, our analysis of a recent effort to project Greenland's contribution to future sea-level suggests that few models reproduce historical mass loss accurately, and that they appear much too confident in the spread of predicted outcomes. The inability of models to reproduce historical observations raises concerns about the models' skill at projecting mass loss. Here we suggest that the future sea level contribution from Greenland may well be significantly higher than reported in that study. We propose a roadmap to enable a more realistic accounting of uncertainties associated with such forecasts, and a formal process by which observations of mass change be used to refine projections of mass change. Finally, we note that tremendous government investment and planning affecting 10s to 100s of millions of people is founded on the work of several tens of scientists involved in a significantly volunteer effort. To achieve the goal of credible projections of ice sheet contribution to sea-level, we strongly believe that investment in research must be commensurate with the scale of the challenge.