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West Antarctic ice loss influenced by internal climate variability and anthropogenic forcing

Holland, Paul R. ORCID: https://orcid.org/0000-0001-8370-289X; Bracegirdle, Thomas J. ORCID: https://orcid.org/0000-0002-8868-4739; Dutrieux, Pierre; Jenkins, Adrian ORCID: https://orcid.org/0000-0002-9117-0616; Steig, Eric J.. 2019 West Antarctic ice loss influenced by internal climate variability and anthropogenic forcing. Nature Geoscience, 12. 718-724. https://doi.org/10.1038/s41561-019-0420-9

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This is the author accepted version of Holland, P.R., Bracegirdle, T.J., Dutrieux, P. et al. West Antarctic ice loss influenced by internal climate variability and anthropogenic forcing. Nat. Geosci. 12, 718–724 (2019) doi:10.1038/s41561-019-0420-9 Please note, this may differ from the version of record. Please see publisher reuse policy at: https://www.nature.com/nature-research/editorial-policies/self-archiving-and-license-to-publish#terms-for-use.
Manuscript_revised_revised_final.pdf - Accepted Version

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Abstract/Summary

Recent ice loss from the West Antarctic Ice Sheet has been caused by ocean melting of ice shelves in the Amundsen Sea. Eastward wind anomalies at the shelf break enhance the import of warm Circumpolar Deep Water onto the Amundsen Sea continental shelf, which creates transient melting anomalies with an approximately decadal period. No anthropogenic influence on this process has been established. Here, we combine observations and climate model simulations to suggest that increased greenhouse gas forcing caused shelf-break winds to transition from mean easterlies in the 1920s to the near-zero mean zonal winds of the present day. Strong internal climate variability, primarily linked to the tropical Pacific, is superimposed on this forced trend. We infer that the Amundsen Sea experienced decadal ocean ariability throughout the twentieth century, with warm anomalies gradually becoming more prevalent, offering a credible explanation for the ongoing ice loss. Existing climate model projections show that strong future greenhouse gas forcing creates persistent mean westerly shelf-break winds by 2100, suggesting a further enhancement of warm ocean anomalies. These wind changes are weaker under a scenario in which greenhouse gas concentrations are stabilized.

Item Type: Publication - Article
Digital Object Identifier (DOI): https://doi.org/10.1038/s41561-019-0420-9
ISSN: 0028-0836
Additional Keywords: climate and earth system modelling, cryospheric science, physical oceanography
Date made live: 12 Aug 2019 16:11 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/521027

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