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

Paul R. Holland*, Thomas J. Bracegirdle, Pierre Dutrieux, Adrian Jenkins, Eric J. Steig

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)
10 Downloads (Pure)

Abstract

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 variability 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.

Original languageEnglish
Pages (from-to)718-724
Number of pages7
JournalNature Geoscience
Volume12
Issue number9
Early online date12 Aug 2019
DOIs
Publication statusPublished - 1 Sep 2019
Externally publishedYes

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