A GEOMAR study finds the Southern Ocean could release massive stored heat if CO₂ levels fall to net-negative, causing decades or a century of renewed warming. The research underscores the ocean’s powerful climate role and the urgent need to cut emissions now.
The Southern Ocean has been storing heat. It could be released in a giant, 100-year "burp."
Earth's Southern Ocean (the seas around Antarctica) has long acted as a heat reservoir, absorbing most of the excess warmth from greenhouse gas pollution. New research indicates that if greenhouse gas levels are eventually cut and even reversed, this ocean may one day release much of that stored heat back into the atmosphere. GEOMAR researchers say such a sudden “thermal burp” of heat could drive warming for a century.
According to a GEOMAR Helmholtz Centre modelling study, the Southern Ocean has absorbed about 90% of the excess heat from greenhouse emissions. In the model scenario, CO₂ levels double, then fall to net-negative; as the world cools and sea ice grows, very cold, dense surface water eventually sinks, driving deep ocean convection. This creates a sudden ‘heat burp' as the buried warmth is released to the atmosphere. Ivy Frenger, co-author of the study, likens the ocean to an “exhaust valve” that allows buried heat to escape. The model suggests this warming could then continue at roughly the current rate for decades or even a century.
The scenario is highly idealised. It assumes a dramatic shift to net-negative CO₂ that is currently unrealistic and omits processes like ice-sheet melt. Frenger emphasises that cutting emissions now is still crucial: “the most important step right now is to reduce current CO₂ emissions to net zero, in order to avoid a further perturbation to the climate system”. It shows the Southern Ocean's vast heat reservoir could influence climate for generations, reinforcing the need for urgent emissions cuts.
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