A new fleet of autonomous ocean drones has begun a five-year effort to monitor the Southern Ocean, targeting one of the biggest unanswered questions in climate science: exactly how much carbon dioxide is being absorbed by the waters surrounding Antarctica.
The first uncrewed surface vehicle (USV) departed from Hobart this week under a major international research collaboration led by Australia’s national science agency, CSIRO, alongside partners from the United States, South Africa and other institutions. The wind and solar-powered Saildrone vessels will be deployed throughout the year, gathering data from some of the most remote and inhospitable ocean regions on Earth.
Scientists regard the Southern Ocean as a critical component of the global climate system. While the world’s oceans absorb roughly one-third of the carbon dioxide taken up from the atmosphere each year, the Southern Ocean alone is responsible for about 40 percent of that oceanic uptake. Despite its importance, researchers still lack enough observations to accurately assess how this vital carbon sink behaves and how it may change in the future.
The Saildrone Explorers are designed to fill those gaps. Each deployment is expected to cover approximately 22,000 kilometres while circumnavigating Antarctica. Operating for months at sea without a crew, the vessels will continuously collect atmospheric and oceanographic measurements, including air temperature, wind conditions, atmospheric carbon dioxide, sea surface temperature, salinity, dissolved oxygen and seawater carbon dioxide concentrations.
Researchers say the programme represents the first long-term campaign dedicated to using autonomous surface vehicles to study the Southern Ocean across seasons and regions where conventional ship-based observations are scarce. The ability to redirect the drones during the mission will allow scientists to target areas where additional measurements are most needed, while advanced modelling and artificial intelligence tools will help interpret the incoming data.
The project, known as Constraining Ocean Carbon with Optimized Observing (COCO2), is expected to contribute directly to future Global Carbon Budget assessments. By improving understanding of how the Southern Ocean absorbs and stores carbon, scientists hope to strengthen projections of future climate change and reduce one of the largest uncertainties in the global carbon cycle.