Reassessment of the Potential Sea-Level Rise from a Collapse of the West Antarctic Ice Sheet

Collapse and Rise The West Antarctic Ice Sheet (WAIS) is thought to be inherently unstable and susceptible to rapid collapse if it reaches a certain warming threshold. Although such an event is considered unlikely, to predict the consequences of collapse it is important to know how much sea level would rise in such a case. The WAIS is thought to contain enough ice to raise sea level by 5 to 7 meters were it to collapse. Bamber et al. (p. 901 , see the cover; see the Perspective by Ivins ) have reassessed that number, on the basis of better data on the geometry of the WAIS, and conclude that its sudden collapse would raise sea level by about 3.2 meters, on average, with large and important regional variations. Although this is only about half as much as previously thought, its impact on coastal areas would still be devastating.