Changes in accumulated snowfall over the Antarctic Ice Sheet have an immediate and time-delayed impact on global mean sea level. The immediate impact is due to the instantaneous change in freshwater storage over the ice sheet, whereas the time-delayed impact acts in opposition through enhanced ice-dynamic flux into the ocean1. Here, we reconstruct 200 years of Antarctic-wide snow accumulation by synthesizing a newly compiled database of ice core records2 using reanalysis-derived spatial coherence patterns. The results reveal that increased snow accumulation mitigated twentieth-century sea-level rise by ~10 mm since 1901, with rates increasing from 1.1 mm decade−1 between 1901 and 2000 to 2.5 mm decade−1 after 1979. Reconstructed accumulation trends are highly variable in both sign and magnitude at the regional scale, and linked to the trend towards a positive Southern Annular Mode since 19573. Because the observed Southern Annular Mode trend is accompanied by a decrease in Antarctic Ice Sheet accumulation, changes in the strength and location of the circumpolar westerlies cannot explain the reconstructed increase, which may instead be related to stratospheric ozone depletion4. However, our results indicate that a warming atmosphere cannot be excluded as a dominant force in the underlying increase.
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The code for generating the reconstructions is available from the NASA Goddard Cryosphere data portal (https://neptune.gsfc.nasa.gov/csb/).
The snow accumulation reconstructions generated and analysed during this study are available from the NASA Goddard Cryosphere data portal (https://neptune.gsfc.nasa.gov/csb/). The reanalysis data are available as follows: CFSR (https://rda.ucar.edu/pub/cfsr.html), ERA-Interim (https://www.ecmwf.int/en/forecasts/datasets/archive-datasets/reanalysis-datasets/era-interim) and MERRA-2 (https://disc.gsfc.nasa.gov/). The ice core records are hosted at https://ramadda.data.bas.ac.uk/repository/entry/show?entryid=83f2ca40-04b5-4029-a04c-c18b202dc2f8.
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We acknowledge everyone involved in the collection and analysis of the ice core records used in our reconstruction, as well as A. Barker and J. Lenaerts for manuscript comments. B.M. and E.R.T. were supported by NASA’s ICESat-2 Project Science Office and the British Antarctic Survey (Natural Environment Research Council), respectively.
The authors declare no competing interests.
Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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Medley, B., Thomas, E.R. Increased snowfall over the Antarctic Ice Sheet mitigated twentieth-century sea-level rise. Nature Clim Change 9, 34–39 (2019). https://doi.org/10.1038/s41558-018-0356-x
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