Assessing the Ice: Sea Level Rise Predictions from the West Antarctic Ice Sheet

The West Antarctic Ice Sheet (WAIS) has been a puzzle for glaciologists trying to understand its behavior and future. As a marine ice sheet, it is inherently unstable. However, until recently, the best available evidence suggested that WAIS was stable for now. Its threat and promise of a rapid disintegration, and subsequent significant global sea level rise, seemed suspended into the unimaginable future, especially according to political timeframes. In the most recent iteration of the Intergovernmental Panel on Climate Change assessment reports, however, it became apparent that WAIS was more unstable than previously thought; in fact, the ice sheet was already beginning to show rapid changes in some areas. These findings led to a disintegration of the previous sea level rise predictions (O’Reilly et al., forthcoming). This paper tracks the history of the WAIS assessment process, from the small scale, informal workshops and single-authored reports that kickstarted WAIS assessments (Revelle 1983), to the elaborate, international, and diplomatic assessments produced by the Intergovernmental Panel on Climate Change (1991, 1995, 2001, 2007). How have the epistemological frameworks shifted in relationship to the bureaucratic structures? How have assessors’ tactics accommodated (or not) the available research? This paper contends that subtle shifts in scientific inquiry, bolstered by increasingly programmatic climate change research and policy endeavors, helped to articulate the swings in sea level rise predictions over the past several decades.