Southern Ocean Could Release Stored Heat, Delaying Global Cooling by a Century, Scientists Warn

Southern Ocean Could ‘Burp’ Stored Heat, Delaying Global Cooling by a Century, Scientists Warn.

The Southern Ocean, surrounding Antarctica, has long acted as a major heat reservoir, absorbing roughly 90% of the excess warmth from greenhouse gas emissions. New research from GEOMAR Helmholtz Centre suggests that even if greenhouse gas levels are drastically reduced in the future, this buried heat could one day be released back into the atmosphere—a sudden “thermal burp” that could sustain warming for up to a century.

A Hidden Heat Reservoir

The study’s modelling scenario envisions CO₂ levels doubling and then falling to net-negative. As the world cools and sea ice expands, extremely cold, dense surface water sinks, triggering deep ocean convection. This process allows the stored heat to escape, driving a prolonged period of atmospheric warming. Co-author Ivy Frenger describes the Southern Ocean as an “exhaust valve” for the planet’s buried heat.

Implications and Caution

The researchers stress that the scenario is highly idealised, excluding factors like ice-sheet melt and relying on assumptions about net-negative emissions that are currently unrealistic. Frenger emphasizes that cutting emissions now remains critical: “The most important step right now is to reduce current CO₂ emissions to net zero, in order to avoid further perturbation to the climate system.”

The study highlights the Southern Ocean’s role as a long-term climate regulator, showing that its hidden heat could influence global temperatures for generations and reinforcing the urgency of immediate climate action.