A deglacial model for Antarctica: geological constraints and glaciological modelling as a basis for a new model of Antarctic glacial isostatic adjustment

By P. Whitehouse, Michael J. Bentley, A. Brocq. 2012

278 citations recorded by the source corpus.

Abstract We present a new reconstruction of the Antarctic Ice Sheets between 20 ka BP and the present day. Our reconstruction is derived using a numerical model to generate a physically-consistent ice surface across the whole of the continent. We define the extent of the ice sheet at five time slices; 20, 15, 10, 5 and 0 ka BP, assuming an equilibrium state for the 20 ka BP time slice, and a transient state for the deglacial time slices. The evolution of the ice sheet within the numerical model is driven by variations in temperature, accumulation rate, and relative sea level. In order to reconstruct the concave profile of the ice sheet in marine-grounded regions, such as the Ross and Weddell Seas, we force our model to develop channels of faster flow by defining greater basal sliding along the trajectory of former ice streams. We find a strong dependence upon the basal sliding parameters, and also the position of the grounding line. We use an extensive data base of geological and glaciological data to constrain our ice-sheet reconstruction. Grounding-line extent is prescribed from marine geological data and we test ice-sheet thickness against onshore geological data at 62 sites. Of the five time slices considered, our 20 ka BP reconstruction is the best constrained by data and has an RMS misfit of 147.6 m when compared to observations of ice thickness change between 20 ka BP and the present day. Across all time slices there are large regions of the ice-sheet which are poorly constrained, especially after 20 ka BP. We estimate the spatial distribution of uncertainty in our ice-sheet reconstruction, and note that the solutions are least reliable in regions of complex topography. We predict that the Antarctic Ice Sheets contributed 9 ± 1.5 m of eustatic sea level to the global ocean between 20 ka BP and the present, and our reconstruction with minimum misfit contributes ∼8 m eustatic sea level during this period. These values, which we argue are an upper bound, are lower than many previous estimates. The reconstructed pattern of ice unloading can serve as a new input for glacial isostatic models.

Subfields: Atmospheric Science, Management, Monitoring, Policy and Law

View Paper: https://www.semanticscholar.org/paper/75bfff44379bca49588493dc2574c866fcd53f4c

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Atmospheric Science

In Management, Monitoring, Policy and Law

Citations in the corpus

Time‐variable gravity observations of ice sheet mass balance: Precision and limitations of the GRACE satellite data (2013, background): “[9] New regional ice deglaciation models have recently been developed to match a variety of geologic, glaciological, and geodetic observations [e.g., Simpson et al., 2009; Whitehouse et al., 2012; Ivins et al., 2013].”
Antarctic contribution to sea level rise observed by GRACE with improved GIA correction (2013, background): “…the AIS volume changes as a function of time since LGM ( 21 ka) for a number of contemporary models including M11 [Mackintosh et al., 2011], W12a [Whitehouse et al., 2012b], and PDcPaSEb [Briggs, 2012], which incorporate local geological constraints, and the ICE-5G (version 1.2) [Peltier, 2004]…”
Glacial isostatic adjustment modelling: historical perspectives, recent advances, and future directions (2018, methodology): “…of the lithosphere are often inferred by comparing GIA model output with observations that reflect past and present rates of solid Earth deformation, such as GPS time series or records of past relative 430 sea-level change (e.g. Lambeck et al., 1998;Whitehouse et al., 2012b;Argus et al., 2014).”
Space geodesy constrains ice age terminal deglaciation: The global ICE‐6G_C (VM5a) model (2015, background): “However, an additional data set has recently become available [Whitehouse et al., 2012a], consisting of exposure age dates on “trimline elevations” PELTIER ET AL.”
A simple inverse method for the distribution of basal sliding coefficients under ice sheets, applied to Antarctica (2012, methodology): “In future work we plan to combine the inverse method with transient runs through the last deglaciation, comparing in depth with relevant data (Sect. 8; cf. Briggs et al., 2011; Whitehouse et al., 2012).”
Computations of the viscoelastic response of a 3-D compressible Earth to surface loading: an application to Glacial Isostatic Adjustment in Antarctica and Canada (2012, background): “D spherical Earth (e.g. Latychev 2005 and Whitehouse et al. 2006 for finite-volume modelling of a compressible Earth; Martinec 2000 and Tanaka et al. 2011 for spectral finite-element modelling of a compressible Earth; Martinec 1999 for spectral, initial value approach for a compressible Earth; Wu &…”
A new glacial isostatic adjustment model for Antarctica: calibrated and tested using observations of relative sea‐level change and present‐day uplift rates (2012, methodology): “Whitehouse et al. (2012) provide an estimate of the uncertainty in ice thickness change since the LGM due to incomplete knowledge of the climate history, geothermal heat flux distribution, rheological properties and relative sea-level forcing for Antarctica.”
Effect of GIA models with 3D composite mantle viscosity on GRACE mass balance estimates for Antarctica (2015, methodology): “Ice model W12a ICE-5G Earth model Whitehouse et al. (2012b) HF10D S4D S10W VM2 Peltier (2004) HF10D S4D S10W Misfit (Eq.”