EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Recent recovery of Antarctic Bottom Water formation in the Ross Sea driven by climate anomalies

Alessandro Silvano1,2,3, Annie Foppert2,3,4, Steve Rintoul2,3,4, Paul Holland5, Takeshi Tamura6,7, Noriaki Kimura8, Pasquale Castagno9, Pierpaolo Falco9,10, Giorgio Budillon9,10, Alexander Haumann5,11, Alberto Naveira Garabato1, and Alison Macdonald12
Alessandro Silvano et al.
  • 1University of Southampton, Southampton, United Kingdom of Great Britain – England, Scotland, Wales (
  • 2CSIRO Oceans & Atmosphere, Hobart, Tasmania, Australia
  • 3Centre for Southern Hemisphere Oceans Research, Hobart, Tasmania, Australia
  • 4Australian Antarctic Program Partnership, University of Tasmania, Hobart, Tasmania, Australia
  • 5British Antarctic Survey, Cambridge, UK
  • 6National Institute of Polar Research, Tachikawa, Japan
  • 7SOKENDAI, Graduate University for Advanced Studies, Tachikawa, Japan
  • 8Atmosphere and Ocean Research Institute, The University of Tokyo, Tokyo, Japan
  • 9Department of Sciences and Technologies, Parthenope University, Naples, Italy
  • 10Consorzio Nazionale Interuniversitario per le Scienze del Mare, Rome, Italy
  • 11Atmospheric and Oceanic Sciences, Princeton University, Princeton, NJ, USA
  • 12Woods Hole Oceanographic Institution, Woods Hole, MA, USA

Antarctic Bottom Water (AABW) supplies the lower limb of the global overturning circulation, ventilates the abyssal ocean and sequesters heat and carbon on multidecadal to millennial timescales. AABW originates on the Antarctic continental shelf, where strong winter cooling and brine released during sea ice formation produce Dense Shelf Water, which sinks to the deep ocean. The salinity, density and volume of AABW have decreased over the last 50 years, with the most marked changes observed in the Ross Sea. These changes have been attributed to increased melting of the Antarctic Ice Sheet. Here we use in situ observations to document a recovery in the salinity, density and thickness (that is, depth range) of AABW formed in the Ross Sea, with properties in 2018–2019 similar to those observed in the 1990s. The recovery was caused by increased sea ice formation on the continental shelf. Increased sea ice formation was triggered by anomalous wind forcing associated with the unusual combination of positive Southern Annular Mode and extreme El Niño conditions between 2015 and 2018. Our study highlights the sensitivity of AABW formation to remote forcing and shows that climate anomalies can drive episodic increases in local sea ice formation that counter the tendency for increased ice-sheet melt to reduce AABW formation.

How to cite: Silvano, A., Foppert, A., Rintoul, S., Holland, P., Tamura, T., Kimura, N., Castagno, P., Falco, P., Budillon, G., Haumann, A., Naveira Garabato, A., and Macdonald, A.: Recent recovery of Antarctic Bottom Water formation in the Ross Sea driven by climate anomalies, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8371,, 2021.

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