New research suggests that as atmospheric CO2 levels fall, the Southern Ocean may shift from being a carbon sink to a carbon source. Using climate models, researchers simulated net-zero and negative emissions scenarios and found that the ocean could start releasing stored carbon back into the atmosphere over time. This is a gradual process with significant implications for net-zero planning and carbon removal strategies. The main drivers are warming surface waters, which hold less CO2, and declining alkalinity. The model estimates future emissions could reach 8.5 to 8.6 grams of carbon per square meter annually, compared to absorbing 2.8 grams per square meter in 2001. Uncertainties remain, including the role of Antarctic ice, so sustained monitoring of the Southern Ocean's carbonate system is essential to confirm these findings.
