Dense, cold water from the shelf seas off Antarctica flows northwards in the strongest mean current discovered at depths greater than 3,000 metres. Published online in Nature Geoscience, the observations of the vigorous flow along the Kerguelen Plateau near Antarctica reveal a significant branch of the global oceans' deep overturning circulation.

Yasushi Fukamachi and colleagues used an array of current meters in the deep water just east of the Kerguelen Plateau for two years, to monitor the northward flow at depth. They estimate that, on average, about eight million cubic metres of water colder than 0.2℃ are transported towards lower latitudes each second, roughly four times as much as previously documented in a different branch of deep Antarctic outflow. The so-called Antarctic Bottom Water forms the densest and deepest water mass involved in the global ocean circulation, which in turn is an important component of the climate system.

In an accompanying News and Views article, Alejandro Orsi says: "Vital oceanographic measurements, such as those reported by Fukamachi and co-authors from the Kerguelen Plateau, will continue to benefit climate scientists".