Southern Ocean May Become Carbon Source With Climate Mitigation

Scientists warn that the global effort to cap warming at 1.5 °C above pre‑industrial levels, which relies on achieving net‑zero emissions and actively removing carbon dioxide (CO₂) from the atmosphere, could have an unforeseen side effect. A new study published in *Science Advances* used climate simulations to show that the Southern Ocean surrounding Antarctica may shift from being a significant carbon sink to becoming a net source of CO₂ as atmospheric concentrations fall.

The research highlights the complex feedbacks in the Earth system. While reducing CO₂ is essential to limit extreme weather, sea‑level rise, ecosystem loss and the risk of triggering irreversible climate tipping points, the Southern Ocean’s response could undermine some of those gains. The model suggests that changes in ocean circulation, temperature, and biological activity could release stored carbon, potentially offsetting the benefits of emissions reductions and carbon‑removal technologies.

These findings underscore the need for continuous monitoring of oceanic carbon fluxes and for climate policy to incorporate adaptive strategies that account for such nonlinear feedbacks. Ensuring that mitigation pathways remain effective will require a deeper understanding of regional climate dynamics and the development of flexible, evidence‑based approaches to carbon management.