Geochemical Evidence for Quaternary Sea-level Changes

Throughout the Quaternary, sea level has risen and fallen as continental ice sheets have waned and waxed. The main cause of sea-level change has been variation in the total volume of continental ice and resulting change in the fraction of the Earth’s surface H₂O contained in the ocean. Today more than 97% of the Earth’s surface H₂O is in the ocean and less than 2% is stored as ice in continental glaciers, with groundwater making up the bulk of the remainder. Of the total continental ice (ice above sea level),,80% is contained in the east Antarctic ice sheet, 10% in the west Antarctic ice sheet, and the final 10% in the Greenland ice sheet. If all continental ice were to melt, sea level would rise by,70 m. During the last glacial maximum (LGM), sea level was,125 m lower than present, equivalent to 3% more surface H₂O stored as continental ice. Because of its relationship to continental ice volume, an accurate Quaternary sea-level curve has been a long-term goal of scientists interested in ice-age cycles and their causes. Although sea level is closely related to continental ice volume, it is also a function of other variables, most notably isostatic effects (see Clark et al. (1978) and review of Peltier (1998) and references therein). Sea-level change can be divided into a eustatic component, which depends only on shifts in the mass of H₂O between continental ice and the ocean, and an isostatic component, which is site specific and is a function of.