Widespread low rates of Antarctic glacial isostatic adjustment revealed by GPS observations

Abstract

Bedrock uplift in Antarctica is dominated by a combination of glacial isostatic adjustment (GIA) and elastic response to contemporary mass change. Here, we present spatially extensive GPS observations of Antarctic bedrock uplift, using 52% more stations than previous studies, giving enhanced coverage, and with improved precision. We observe rapid elastic uplift in the northern Antarctic Peninsula. After considering elastic rebound, the GPS data suggests that modeled or empirical GIA uplift signals are often over‐estimated, particularly the magnitudes of the signal maxima. Our observation that GIA uplift is misrepresented by modeling (weighted root‐mean‐squares of observation‐model differences: 4.9–5.0 mm/yr) suggests that, apart from a few regions where large ice mass loss is occurring, the spatial pattern of secular ice mass change derived from Gravity Recovery and Climate Experiment (GRACE) data and GIA models may be unreliable, and that several recent secular Antarctic ice mass loss estimates are systematically biased, mainly too high.

Trends and acceleration in global and regional sea levels since 1807

“…13 shows the 20th . For Rothera and Argentine Islands GIA corrections from Thomas et al (2011) are significantly larger than those from the ICE 5G model, however, these large GIA corrections are associated with break-up of Larsen B Ice shelf and have been applied only for the post breakup period since 2002, and which account for only 2-3 cm of total sea level rise by 2009.…”

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

“…Ivins and Sammis, 1995;Martinec, 2000;Kaufmann et al, 2005;Latychev et al, 2005b;Paulson et al, 2005;Steffen et 575 al., 2006;A. et al, 2013), possibly defined via use of a non-linear creep law -where the viscosity depends on the timevarying stress field van der Wal et al, 2013). The effect of including plate boundaries -which affect the horizontal transmission of stress -and variations in the thickness and rheology of the lithosphere have also been explored (Latychev et al, 2005a;Kuchar and Milne, 2015).…”

“…Ivins and Sammis, 1995;Latychev et al, 2005b). This derivation is not straightforward, and in particular, compositional effects must be accounted for when interpreting seismic velocity perturbations in terms of temperature perturbations (Wu et al, 2013). If a power-law approach is used, grain-scale deformation of mantle material is described by diffusion and dislocation creep through the use of a non-linear relationship where the strain rate depends on stress to some power.…”

“…Peltier, 2004;Steffen et al, 2009;Mazzotti et al, 2011;Memin et al, 2011;Sato et al, 2012), while the relationship between surface gravity change and uplift rates can be employed to constrain GIA in regions where ice history and Earth structure are poorly known (e.g. Wahr 425 et al, 1995;Purcell et al, 2011;van Dam et al, 2017 …”

“…( Thomas et al, 2011;Nield et al, 2014). Horizontal GPS rates are often more precise than vertical rates by an order of magnitude (King et al, 2010), but before they can be compared with GIA model output the velocity field due to plate motion must be removed.…”