Quaternary sea-level changes

Abstract

Relative changes of the land/sea interface have occurred throughout geologic time. Although these changes can be caused by several factors, alternating global events such as glaciation-deglaciation are the most effective in the Quaternary period. Other causes, e.g. volumetric changes in the mid-oceanic ridge system, have been proposed to explain sea-level changes from the Upper Cretaceous to the mid-Miocene (Pitman, 1978). However, the evidence available suggests that no uniform response can be expected worldwide as a result of global, glacio-eustatic events. This is due to tectonics, glacial isostasy, hydroisostasy and geoidal configuration of the ocean surface, among other variables. All these factors have been operative at various timescaIes and have been subject to local and regional variations. This explains why sea-level curves for the Holocene fail to provide a uniform, global trend. Instead, several local curves have been derived from many areas. The variability of postglacial sea levels has been explained by different models considering glacial isostasy (Clark et al., 1978), the redistribution of ice and water loads from Antarctic deglaciation (Peltier, 1988), and future sea-level rise due to the melting of the Greenland and Antarctic ice sheets has been predicted by Clark and Primus (1987). As will be discussed more fully later, a global warming is expected to take place due to the increasing accumulation of CO2 and other