LATE QUATERNARY VARIATIONS IN RELATIVE SEA-LEVEL DUE TO GLACIAL CYCLEPOLAR WANDER

Growth and decay of continental ice sheets can excite significant moti on of the Earth's rotation pole and cause a complex spatio-temporal pa ttern of changes in relative sea level. These two effects have general ly been considered separately, but may interact in important ways. In particular, a simple model of the melting of the Laurentide ice sheet causes a uniform eustatic sea level rise of 55 m, and also induces a m otion of the rotation pole by 0.1 to 1 degree, depending on viscosity structure in the mantle. This motion produces a secular pole tide, whi ch is a spherical harmonic degree 2, order 1 component of the relative sea level pattern, with peak-to-peak amplitude of 20 to 40 m. The max imum effect is along the great circle passing through the path of the pole and at latitudes of +/-45 degrees. This secular pole tide has bee n ignored in most previous attempts to estimate from global patterns o f relative sea level change. It has a large influence along the East c oast of North America and the West coast of South America, and signifi cantly contributes to present day rates of relative sea level change.