A Method for Obtaining Geophysically Rigorous Estimates of Sea-Level Rate and Acceleration

Smithsonian Institution Astrophysical Observatory, Cambridge MA

Investigators

Abstract

Davis 0125518 The investigators will undertake research to obtain the most accurate and geophysically rigorous determination of global sea-level change to date. To correct tide-gauge data for the effect of postglacial rebound, the investigators will use state-of-the art theory, Earth models, and observations. A new element of the proposed research will be the use of Global Positioning System (GPS) data to correct for vertical crustal motion. This study requires careful assessment of various GPS data sets that could potentially contribute to this study, because it is difficult to achieve the required level of accuracy in the vertical rate with GPS. Nevertheless, such accuracy, at least on a regional basis, is possible. A recent analysis of GPS and tide-gauge data from Scandinavia, for example, yields a regional value for Baltic sea-level rise of 2.1 +/- 0.3 mm/yr. The Baltic tide-gauge data set, although potentially a powerful contributor to studies of sea-level change, has never before been used in a global analysis due to its contamination by postglacial rebound. This research will enable quantification of the relative contributions to present-day sea level change of thermal expansion of the oceans and the ongoing melting of glaciers and ice sheets, knowledge that is crucial to our ability to understand the causes and the present state of climate change.