Effect of irregular fluctuations in Antarctic precipitation on global sea level

Abstract

One of the reasons for the continuing interest in the global sea level is that secular variations may be caused by climatic changes. Such a change could, for example, be an atmospheric warming due to CO₂ accumulation. Changes in the amount of ice in the major ice sheets will be reflected in secular variations of sea level; it has, for example, been suggested that ice-shelf thinning may change the drainage of parts of the Antarctic Ice Sheet¹. Attempts to monitor climatic change by measuring global sea level will, however, be complicated by random fluctuations of the ice volume in the major ice sheets, themselves the consequence of random variations in the ice accumulation rate. Precipitation rates are highly variable, and this also applies to Antarctica², which stores most of the continental ice mass. By means of a simple model for ice flow in the Antarctic, together with proxy data on precipitation variability derived from ice cores, I show that long-term sea-level variations with a standard deviation of roughly 5 cm are to be expected on this account. This ‘climatic noise’ is comparable in magnitude with many of the secular effects now being sought.