Accelerated freshening of Antarctic Bottom Water over the last decade in the Southern Indian Ocean
Menezes, Viviane V.
Macdonald, Alison M.
MetadataShow full item record
KeywordSalinity; AABW; Changes; Water masses; T-S properties; Iceberg; Calving; Antartica; Abyss; Climate change
Southern Ocean abyssal waters, in contact with the atmosphere at their formation sites around Antarctica, not only bring signals of a changing climate with them as they move around the globe but also contribute to that change through heat uptake and sea level rise. A repeat hydrographic line in the Indian sector of the Southern Ocean, occupied three times in the last two decades (1994, 2007, and, most recently, 2016), reveals that Antarctic Bottom Water (AABW) continues to become fresher (0.004 ± 0.001 kg/g decade−1), warmer (0.06° ± 0.01°C decade−1), and less dense (0.011 ± 0.002 kg/m3 decade−1). The most recent observations in the Australian-Antarctic Basin show a particularly striking acceleration in AABW freshening between 2007 and 2016 (0.008 ± 0.001 kg/g decade−1) compared to the 0.002 ± 0.001 kg/g decade−1 seen between 1994 and 2007. Freshening is, in part, responsible for an overall shift of the mean temperature-salinity curve toward lower densities. The marked freshening may be linked to an abrupt iceberg-glacier collision and calving event that occurred in 2010 on the George V/Adélie Land Coast, the main source region of bottom waters for the Australian-Antarctic Basin. Because AABW is a key component of the global overturning circulation, the persistent decrease in bottom water density and the associated increase in steric height that result from continued warming and freshening have important consequences beyond the Southern Indian Ocean.
© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Science Advances 3 (2017): e1601426, doi:10.1126/sciadv.1601426.
The following license files are associated with this item:
Except where otherwise noted, this item's license is described as Attribution-NonCommercial 4.0 International
Showing items related by title, author, creator and subject.
Precession-driven changes in Iceland–Scotland Overflow Water penetration and bottom water circulation on Gardar Drift since ~ 200 ka Elmore, Aurora C.; Wright, James D.; Chalk, Thomas B. (2015-09-21)Benthic foraminiferal stable isotopic records from a transect of sediment cores south of the Iceland-Scotland Ridge reveal that the penetration depth of Iceland-Scotland Overflow Water (ISOW) varied on orbital timescales ...
Recent changes in the Labrador Sea Water within the Deep Western Boundary Current southeast of Cape Cod Pena-Molino, Beatriz; Joyce, Terrence M.; Toole, John M. (2011-07-20)Water properties measured by the central mooring in the Line W mooring array southeast of Cape Cod document a large character shift during the period of November 2001 to April 2008. The observed temperature, salinity and ...
Abrupt changes of temperature and water chemistry in the late Pleistocene and early Holocene Black Sea Bahr, Andre; Lamy, Frank; Arz, Helge W.; Major, Candace O.; Kwiecien, Olga; Wefer, Gerold (American Geophysical Union, 2008-01-12)New Mg/Ca, Sr/Ca, and published stable oxygen isotope and 87Sr/86Sr data obtained on ostracods from gravity cores located on the northwestern Black Sea slope were used to infer changes in the Black Sea hydrology and water ...