Southern Ocean observations demonstrate continued changes in salinity, temperature and density with significant global consequences

A recent publication by Viviane V. Menezes and colleagues (Science Advances, Jan 25 2017) has shown that Antarctic Bottom Water (AABW) has continued to become fresher, warmer and less dense. The results are based on repeat observations (1994, 2007, 2016) from the same hydrographic line in the Southern Ocean. They show a particularly striking acceleration in AABW freshening between 2007 and 2016. The authors suggest one factor in the freshening may be linked to the Mertz Glacier Tongue calving event in 2010. Because AABW is a key component of the global overturning circulation, changes from continued warming and freshening have important consequences beyond the Southern Indian Ocean.

Viviane V. Menezes, Alison M. Macdonald and Courtney Schatzman, “Accelerated freshening of Antarctic Bottom Water over the last decade in the Southern Indian Ocean”, Science Advances 25 Jan 2017: Vol. 3, no. 1, e1601426 DOI: 10.1126/sciadv.1601426