| Summary: | Decadal trends in the properties of seawater adjacent to Antarctica are poorly known, and the mechanisms responsible for such changes are uncertain. Antarctic ice sheet mass loss is largely driven by ice shelf basal melt, which is influenced by ocean-ice interactions and has been correlated with Antarctic Continental Shelf Bottom Water (ASBW) temperature. We document the spatial distribution of long-term large-scale trends in temperature, salinity, and core depth over the Antarctic continental shelf and slope. Warming at the seabed in the Bellingshausen and Amundsen seas is linked to increased heat content and to a shoaling of the mid-depth temperature maximum over the continental slope, allowing warmer, saltier water greater access to the shelf in recent years. Regions of ASBW warming are those exhibiting increased ice shelf melt. © 2014 American Association for the Advancement of Science. Received for publication 15 May 2014. Accepted for publication 27 October 2014. All data used in this manuscript are publicly available; data sources are detailed in the supplementary materials. We thank all officers, crews, and scientists involved in collecting and calibrating the data in the often harsh Southern Ocean environment, as well as everyone involved in making the data publicly available. We thank three anonymous reviewers for helpful discussions and feedback. Supported by the German Federal Ministry for Education and Research (BMBF) project MiKlip (S.S.); NERC Antarctic Funding Initiative research grant GENTOO NE/H01439X/1 (S.S. and K.J.H.); a Grant-in-Aid for Scientific Research of the Ministry of Education, Culture, Sports, Science and Technology, Japan, and a Daiwa Foundation Small Grant (S.A.); and NSF award OPP-1246460 (A.F.T.). Supplemental Material - Schmidtko.SM.pdf
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