GLACIAL REBOUND AND SEA-LEVEL CHANGE - AN EXAMPLE OF A RELATIONSHIP BETWEEN MANTLE AND SURFACE PROCESSES

The problem of glacial rebound provides an outstanding example of the relationship between surface and mantle processes on time scales of 10(3) to 10(5) years. Changes in surface loading of ice and melt-water associated with the growth and decay of the great ice sheets deform the surface of the planet and induces flow in the mantle. A measure of the Earth's response to the changing surface loads and internal deformation is provided by observations of past sea levels relative to the present level, and inversion of these observations provides constraints on both the models of the rheological response of the Earth to loading and on models of the ice sheets. Constraints on ice sheet models include the total volume of the grounded ice at the time of maximum glaciation, the global rates of melting of the ice sheets, the thickness of the ice at maximum glaciation, the extent of ice cover over shallow seas such as the North Sea and the Barents Sea, and the role of Antarctica in the global ice balance. Constraints on mantle parameters include the effective lithospheric thickness and the effective viscosity of the mantle. Some recent results for both sets of parameters are discussed.