The Southern Ocean-focused Constraining Carbon with Optimised Observing (COCO2) research project, which unites researchers in South Africa, Australia and the US, is now under way and will soon be delivering data to the South Africa-based Southern Ocean Carbon Climate Observatory (SOCCO). The institutions involved in the project are the Council for Scientific and Industrial Research (CSIR), which hosts SOCCO, Australia’s Commonwealth Scientific and Industrial Research Organisation, the US National Oceanic and Atmospheric Administration, Columbia University (also in the US), and US uncrewed surface vessel (USV) manufacturer Saildrone. The project is funded by US philanthropic science funding agency Schmidt Sciences.

The Southern Ocean is the ocean that encircles Antarctica, and is under-observed, with data basically available for only the summer months, which is when ships sail down to Antarctica. Yet it is known to be responsible for 40% of the total global oceanic uptake of carbon dioxide, while also being responsible for absorbing 75% of the heat produced by the excess carbon dioxide that stays in the atmosphere. So, instead of ships, COCO2 will use Saildrone’s USVs.

“The Southern Ocean is thus a disproportionally important ocean when it comes to buffering the impacts of climate change,” highlighted CSIR chief researcher and SOCCO head Dr Sandy Thomalia. “South Africa is a big player in the global climate science space and the observations we will collect in the Southern Ocean using these USVs will help close the biggest observational gap in carbon dioxide data during winter.”

The USVs, as the name of their manufacturer (Saildrone) suggests, are wind-powered, while their onboard sensors are solar-powered. The USVs take the form of small sailing boats, and the first was released off Bruny Island, near Hobart, Tasmania, Australia, on September 20. The project will employ four of these USVs, which will be released at three-monthly intervals. Each will sail more than 22 000 km, circumnavigating Antarctica and eventually returning to Hobart, where they will receive maintenance and sensor upgrades.

“We will look at the role of winds, waves and ocean currents to see how they drive changes in carbon dioxide fluxes (fluxes refers to carbon dioxide entering or leaving the water) regionally and seasonally,” explained CSIR SOCCO project lead oceanographer Dr Sarah Nicholson. “The project will focus specifically on obtaining winter measurements, a critical blind-spot in existing observations; ships typically travel south only during summer, so because of lack of ship access, scientists have hardly any observations of the Southern Ocean in winter. There is therefore a seasonal bias we are trying to address.”