Abstract
Along with density and mass variations of the oceans driven by global warming, Glacial Isostatic Adjustment (GIA) in response to the last deglaciation still contributes significantly to present-day sea-level change. Indeed, in order to reveal the impacts of climate change, long term observations at tide gauges and recent absolute altimetry data need to be decontaminated from the effects of GIA. This is now accomplished by means of global models constrained by the observed evolution of the paleo-shorelines since the Last Glacial Maximum, which account for the complex interactions between the solid Earth, the cryosphere and the oceans. In the recent literature, past and present-day effects of GIA have been often expressed in terms of fingerprints describing the spatial variations of several geodetic quantities like crustal deformation, the harmonic components of the Earth’s gravity field, relative and absolute sea level. However, since it is driven by the delayed readjustment occurring within the viscous mantle, GIA shall taint the pattern of sea-level variability also during the forthcoming centuries. The shapes of the GIA fingerprints reflect inextricable deformational, gravitational, and rotational interactions occurring within the Earth system. Using up-to-date numerical modeling tools, our purpose is to revisit and to explore some of the physical and geometrical features of the fingerprints, their symmetries and intercorrelations, also illustrating how they stem from the fundamental equation that governs GIA, i.e., the Sea Level Equation.
Highlights
Since the Glacial Isostatic Adjustment (GIA) caused by the melting of past ice sheets is still contributing to present-day regional and global sea-level variations, understanding its spatio-temporal variability is important to interpret the effects of present climate change
In this work we have reviewed some aspects of GIA, i.e., the response of the Earth to the disequilibrium caused by the melting of the late-Pleistocene ice sheets
Among the processes that concur to present sea-level rise, the special role of GIA has been recognized long ago; only GIA is affected by the rheology of the Earth and, at the same time, it affects significantly the gravity field and the rotational state of the planet
Summary
Since the Glacial Isostatic Adjustment (GIA) caused by the melting of past ice sheets is still contributing to present-day regional and global sea-level variations, understanding its spatio-temporal variability is important to interpret the effects of present climate change. The present-day trends of sea level detected at tide gauges or by satellite altimetry should be certainly affected by contemporary variations in the state of the cryosphere driven by global warming In this context, the question has not been addressed until the work of Plag and Jüettner [19], who have first coined the term of fingerprint (function). Spada and Galassi [21] have quantitatively compared the harmonic power spectrum of contemporary sea-level change to that of GIA, including the contribution due to the disintegration of the past ice sheets and that associated to present deglaciation.
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