Evaluating IPCC Projections of Global Sea-Level Change From the Pre-Satellite Era

Abstract

With an acceleration of global sea-level rise during the satellite altimetry era (since 1993) firmly established, it is now appropriate to examine sea-level projections made around the onset of this time period. Here we show that the mid-range projection from the Second Assessment Report of the IPCC (1995/1996) was strikingly close to what transpired over the next 30 years, with the magnitude of sea-level rise underestimated by only ∼1 cm. Projections of contributions from individual components were more variable, with a notable underestimation of dynamic mass loss from ice sheets. Nevertheless—and in view of the comparatively limited process understanding, modeling capabilities, and computational resources available three decades ago—these early attempts should inspire confidence in presently available global sea-level projections. Such multidecadal evaluations of past climate projections, as presented here for sea-level change, offer useful tests of past climate forecasts, and highlight the essential importance of continued climate monitoring.