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. 2019 Jul 28;46(14):8174-8183.
doi: 10.1029/2019GL082182. Epub 2019 Jul 24.

Trends in Antarctic Ice Sheet Elevation and Mass

Andrew Shepherd  1 , Lin Gilbert  2 , Alan S Muir  2   3 , Hannes Konrad  1   4 , Malcolm McMillan  1   5 , Thomas Slater  1 , Kate H Briggs  1 , Aud V Sundal  1 , Anna E Hogg  1 , Marcus E Engdahl  6
Affiliations

Trends in Antarctic Ice Sheet Elevation and Mass

Andrew Shepherd et al. Geophys Res Lett. .

Abstract

Fluctuations in Antarctic Ice Sheet elevation and mass occur over a variety of time scales, owing to changes in snowfall and ice flow. Here we disentangle these signals by combining 25 years of satellite radar altimeter observations and a regional climate model. From these measurements, patterns of change that are strongly associated with glaciological events emerge. While the majority of the ice sheet has remained stable, 24% of West Antarctica is now in a state of dynamical imbalance. Thinning of the Pine Island and Thwaites glacier basins reaches 122 m in places, and their rates of ice loss are now five times greater than at the start of our survey. By partitioning elevation changes into areas of snow and ice variability, we estimate that East and West Antarctica have contributed -1.1 ± 0.4 and +5.7 ± 0.8 mm to global sea level between 1992 and 2017.

Keywords: Antarctica; altimetry; climate; imbalance; satellite; sea level.

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Figures

Figure 1
Figure 1
(top) Average rate of elevation change in AIS drainage basins (Zwally et al., 2012) between 1992 and 2017 derived from 90 alternative processing scenarios. The optimal scenario is represented by a thick black line, with its estimated 1σ, 2σ, and 3σ uncertainty range shaded in dark, mid, and light gray, respectively. In most basins, the average elevation rate and the spread among scenarios are close to zero. Basins showing the greatest spread among scenarios are either sparsely sampled (15 and 24 to 27) or include changes in ice thickness that are large by comparison to the spread (20 to 22). (bottom) Evaluation of the alternative processing scenarios: (i) in producing average ice sheet elevation rates (top three rows, see also Figure S9), (ii) in relation to their temporal and spatial sampling (middle four rows, see also Figure S3), and (iii) in relation to their difference to precise airborne laser altimetry (Studinger, ; bottom three rows, see also Figure S11). Against these metrics, scenario 4 (thick border) is identified to be the optimal elevation change solution. AIS = Antarctic Ice Sheet; EAIS = East AIS; WAIS = West AIS; APIS = Antarctic Peninsula ice sheet; LEW = leading edge width.
Figure 2
Figure 2
Average rate of Antarctic Ice Sheet elevation change between 1992 and 2017 (top) and within successive 5‐year intervals (bottom) from satellite radar altimetry, smoothed with a 100 km Gaussian filter. Black circles at the pole indicate the southern limit of the CryoSat‐2 (dashed) and other (solid) satellite orbits. Gray boundaries show glacier drainage basins (Zwally et al., 2012). Boundaries show areas of dynamical imbalance that do not (black) and do (green) evolve over time.
Figure 3
Figure 3
Mass change and sea level contribution of areas in a state of ice dynamical imbalance (see Figure 2 for locations) and their estimated 1σ uncertainty (shaded area).
See this image and copyright information in PMC

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Reference From the Supporting Information

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