Glacial Isostatic Adjustment modelling: historical perspectives, recent advances, and future directions

Abstract

Abstract. Glacial Isostatic Adjustment (GIA) describes the response of the solid Earth, the gravitational field, and 5 consequently the oceans to the growth and decay of the global ice sheets. It is a process that takes place relatively rapidly, triggering 100 m-scale changes in sea level and solid Earth deformation over just a few tens of thousands of years. Indeed, the first-order effects of GIA could already be quantified several hundred years ago without reliance on precise measurement techniques and scientists have been developing a unifying theory for the observations for over 200 years. Progress towards this goal required a number of significant breakthroughs to be made, including the recognition that ice sheets were once 10 more extensive, the solid Earth changes shape over time, and gravity plays a central role in determining the pattern of sealevel change. This article describes in detail the historical development of the field of GIA and an overview of the processes involved. Significant recent progress has been made as concepts associated with GIA have begun to be incorporated into parallel fields of research; these advances are discussed, along with the role that GIA is likely to play in addressing outstanding research questions within the field of Earth system modelling. 15

Relative Sea-Level Changes and Ice Sheet History in Finderup Land, North Greenland

“…The Greenland Ice Sheet (GrIS) is a major contributor to global sea level rise, however, its response to future climate changes remains relatively unconstrained (Church et al, 2013;Gregory et al, 2013). Models of glacial isostatic adjustment (GIA) reconstruct past ice sheet fluctuations and give an essential understanding of how the ice sheet responds to a warming climate (Mitrovica and Milne, 2002;Milne et al, 2009;Lecavalier et al, 2014;Whitehouse, 2018). GIA models are fundamental for predicting future scenarios accurately, and are required in order to interpret GPS measurements of uplift caused by present-day ice retreat (Kjeldsen et al, 2015).…”

“…GIA models are fundamental for predicting future scenarios accurately, and are required in order to interpret GPS measurements of uplift caused by present-day ice retreat (Kjeldsen et al, 2015). To ensure accurate predictions, GIA models rely heavily on constraints from field evidence, particularly the timing of ice retreat and the magnitude of isostatic response, which is conveyed through reconstructions of relative sea level (RSL) Sparrenbom et al, 2006a,b;Long et al, 2008Long et al, , 2011Woodroffe et al, 2014;Whitehouse, 2018). Changes in RSL are a product of variations in both global eustatic sea level and local glacial isostasy, the latter being by far the most dominant effect in the near-field area proximal to a large ice sheet (Hay et al, 2014;Dutton et al, 2015;Whitehouse, 2018).…”

“…To ensure accurate predictions, GIA models rely heavily on constraints from field evidence, particularly the timing of ice retreat and the magnitude of isostatic response, which is conveyed through reconstructions of relative sea level (RSL) Sparrenbom et al, 2006a,b;Long et al, 2008Long et al, , 2011Woodroffe et al, 2014;Whitehouse, 2018). Changes in RSL are a product of variations in both global eustatic sea level and local glacial isostasy, the latter being by far the most dominant effect in the near-field area proximal to a large ice sheet (Hay et al, 2014;Dutton et al, 2015;Whitehouse, 2018). RSL has traditionally been reconstructed using bivalve shells and driftwood on elevated marine terraces (Washburn and Stuiver, 1962;Funder, 1989;Hjort, 1997).…”

Major Ice Sheet Change in the Weddell Sea Sector of West Antarctica Over the Last 5,000 Years

“…High mantle viscosity can be related to a long decay time (McConnell, ) and, hence, rebound in response to post‐LGM ice loss is likely to be ongoing today across the southern portion of the SWSE, with the caveat that the timing of post‐LGM ice loss is poorly known. When seeking to reconstruct past ice sheet change using contemporary rates of solid Earth deformation, the trade‐off with Earth rheology leads to significant non‐uniqueness (Whitehouse, ), with an additional complication being that the loss of ice close to flotation will trigger a limited isostatic response. Feedbacks between ice dynamics and isostatic rebound will be greatest in regions where there has been a significant decrease in the thickness of ice above flotation.…”

A Multivariate Approach for Mapping Lithospheric Domain Boundaries in East Antarctica

“…Better working models of the deep lithosphere are needed to progress investigations of the complex interaction between the solid Earth and the cryosphere. For example, glacial isostatic adjustment in response to changes in ice load depends on deep elastic and viscous properties (e.g., Kaufmann et al, ; Whitehouse, ; Whitehouse et al, ). Geothermal heat is identified as a spatially variable and poorly constrained parameter in ice sheet models (e.g., Burton‐Johnson et al, ; Pollard et al, ).…”