Global Change Geodesy: A Geophysical Perspective

Abstract:

It is a truism that as the precision of geodetic measurement techniques improves, the accuracy of the geophysical modeling of processes that contribute to the observations must keep pace. Studies of the Earth’s response to human-induced climate change provide many notable, and pressing, illustrations of this axiom. For example, estimates of recent ice volume changes, as inferred from satellite gravity measurements, tide gauge and satellite-altimetry records of sea level changes, or astronomical and space-geodetic constraints on Earth rotation, require improved theoretical and numerical treatments of ongoing glacial isostatic adjustment in response to the last ice age. However, the interplay between geodesy and geophysics is not a one-way street; geophysical modeling has emphasized, for example, that the geographic variability in sea level measurements – once considered a nuisance in efforts to infer long term trends - provides a powerful constraint on both the individual sources of meltwater and their sum. In this talk, I will discuss a series of case studies that demonstrate how interdisciplinary research at the interface between geodesy and geophysics has recently resolved several outstanding problems in global change research, including Walter Munk’s enigma of global sea-level rise and the apparent failure to close the budget of twentieth century sea level. Moreover, in the same interdisciplinary context, I will highlight uncertainties that currently limit our understanding of polar ice sheet stability in a progressively warming world.