We describe amplitude variations of a 1470-year (y) signal in the oxygen-isotope record from the GISP2 ice-core as a function of continental ice mass as recorded in sea-level variations. The 1470-y signal is closely tied to Dansgaard-Oeschger interstadial events, which perturbed the climate system on a global scale. Large-amplitude 1470-y oscillations occur only if continental ice mass exceeds a threshold level, equivalent to sea level at approximately -45 m and are tied to times of change in ice mass. Minima of the 1470-y signal in the Greenland ice are associated with short time intervals of relatively stable phases of sea level and with reduced climate variability in the entire periodicity range between approximately 550-5000 y. ¿ 1999 American Geophysical Union