Antarctic Bottom Water (AABW)

node · earth · Southern Ocean and the abyssal basins of all three oceans

The densest water in the world ocean, and the one that fills the deepest basins of all three of them. It forms on Antarctic continental shelves where sea ice grows and rejects brine into water already near the freezing point; the resulting shelf water spills down the slope and spreads north along the bottom. There are four main production regions — the Weddell Sea, which is the largest, the Ross Sea, the Adélie Coast and Cape Darnley. Observations and models both indicate it is in retreat: Weddell Sea Bottom Water volume has fallen by around 30 per cent since 1992, and modelling work published in 2023 projects a substantial slowdown of the abyssal overturning cell driven by Antarctic meltwater freshening the shelf water at source.