Glacial crustal rebound, sea levels, and shorelines

Geological, geomorphological, and instrumental records point to a complex and changing relation between land and sea surfaces due to instability of land surfaces, changes in ocean volume, changes in the shape of ocean basins, and changes in oceanographic factors. This results in a complex variation in time and geography that provides insight into the physical processes active in the earth-ocean system, including the history of the ice sheets during the last glacial cycle, the solid earth response to changes in surface loading, and into rates of vertical land movements. On the time scale of the last glacial cycle the dominant global process driving the complex pattern of sea-level change is the growth and decay of the past ice sheets, referred to as glacio-hydro-isostasy. Superimposed on this are the more regional tectonic processes. Comprehensive models of the former are now available that provide the reference field for understanding geologically recent tectonic uplift and subsidence rates, for reconstructing the past-evolution of shorelines and ocean water depths, and for estimating past ice volumes, both globally and regionally.