“The Southern Ocean is a large window by which the atmosphere connects to the interior of the ocean below” – Jean-Baptiste Sallée from British Antarctic Survey, lead author of new publication in the August edition of Nature Geoscience.
Research vessel of the British Antarctic Survey in rough seas of Southern Ocean. The waves don’t tell, but somewhere in this seascape giant downward whirlpools account for 40 percent of the oceans’ CO2 uptake.
Climate scientists knew the ocean surrounding Antarctica is a crucial zone of so called ‘deep water formation’ as part of the thermohaline circulation or meridional overturning circulation (MOC), the interconnected system of water currents that run through the world’s oceans.
That means the Southern Ocean is also a crucial hotspot for CO2 absorption from the atmosphere into the water – about 40 percent of all the CO2 uptake in the oceans takes place in this comparatively marginal stretch of water under the 60th parallel south.
Now a team of scientists of scientists from the British Antarctic Survey (BAS) and Australia’s national research agency, the Commonwealth Scientific and Industrial Research Organisation (CSIRO) have found out the transportation of CO2 to the deep ocean does not take place across large areas of the ocean, but instead occurs in strong, but narrow whirlpools, which seem to have unfixed locations, as they are driven and directed by an interplay of coastal currents, wind fetch and chaotic eddies.
Data was collected by 80 floats across the Southern Ocean, which were deployed in 2002. The floats dive to depths of 2 kilometers.
The wider picture of the MOC system
The Southern Ocean is quite comparable to the North Atlantic, that other important zone of deep water formation – and a driving engine to the MOC. The difference is the larger N-S component of water movements in the North Atlantic, while down south the masses of water have time to linger a bit more and circle around Antarctica before flowing back into the system. In the North Atlantic too recent discoveries show there are large phenomena science had thus far overlooked – like the North Icelandic Jet.
Concerns relating to feared instability of the North Atlantic Gulfstream may also be mirrored down south as other recent research indicates that there may be a Southern Ocean MOC switch too and because there seems to be a decrease in the Antarctic deep water formation.
© Rolf Schuttenhelm | www.bitsofscience.org