Southern Ocean Carbon Sink

Climate Science for Australia's Future

The Ocean as a Carbon Sink


SAZ Sense Voyage

Currently one third of humankind’s current present annual emissions of CO2 are absorbed by the oceans. The oceans act as a carbon sink, that is, a reservoir that accumulates and stores carbon via its physicochemical and biological processes

The Southern Ocean presently absorbs about half of the global ocean total and thus provides a vital service for humankind. Whether or not the Southern Ocean will continue to sequester carbon at the same rate is uncertain. ACE is measuring the uptake of atmospheric CO2 by the ocean, investigating the biological and physical processes that control this uptake and the propensity for these to change.

Diagram: The processes that move CO2 from the atmosphere into the ocean

The biological and physical pumpsCarbon is taken up by the ocean by both the “biological pump” and the “physical pump”. Assessing the ability of these Southern Ocean carbon pumps to continue to contribute to the control of atmospheric CO2 levels is now one of the major uncertainties in balancing global carbon budgets and their response to climate change.

View: Prof Tom Trull discussing the ocean as a carbon sink

The overall goal of this project is to advance the understanding of the oceanic controls of atmospheric CO2 levels, so that carbon budgets can be balanced and the effectiveness of carbon management decisions evaluated. The observations of Southern Ocean CO2 and of the biogeochemical processes controlling CO2 uptake and transfer to the deep sea, will be expanded using ships of opportunity, moored observatories, profiling floats, and dedicated oceanographic research voyages.  The resulting biogeochemical, oceanographic and climate observations will then be synthesized to improve understanding of carbon uptake controls and hence future projections of the role of the Southern Ocean in absorbing emissions.

View: Pier van der Merwe discusses the importance of phytoplankton

Projects and project leaders

•    Assessment of Southern Ocean uptake of atmospheric CO2: Dr Bronte Tilbrook