The Southern Ocean surrounding Antarctica is poised to release stored heat in a prolonged warming cycle, potentially offsetting human efforts to reverse climate change. New climate modeling suggests this “thermal burp” – a sudden surge of heat from deep ocean reserves – could persist for over a century, even as global emissions decline. The phenomenon highlights the complex, delayed responses within Earth’s climate system.
The Ocean as a Heat Sink
Since the Industrial Revolution, the ocean has absorbed over 90% of excess heat generated by human activity, alongside a quarter of all CO2 emissions. The Southern Ocean, in particular, holds roughly 80% of the total heat stored by all oceans. This heat has accumulated over decades, but cannot remain indefinitely. As global temperatures stabilize and eventually fall due to emissions reduction, the ocean will inevitably return this energy to the atmosphere.
Modeling the “Burp”
Researchers predict that as humanity transitions to net-negative emissions – actively removing CO2 from the atmosphere – the Southern Ocean will destabilize. Colder, saltier surface waters will cap warmer deep currents, creating an unstable water column. This will trigger deep convection, effectively releasing the stored heat in a manner similar to current anthropogenic warming rates. The process is not guaranteed, but it represents a plausible outcome based on current climate models.
Why This Matters
The Southern Ocean’s thermal inertia introduces a critical delay in climate response. Even with aggressive emissions reductions, the ocean’s heat release could counteract progress for over a century. This reinforces the urgency of minimizing current pollution, as delaying action only increases the magnitude of future challenges.
The Southern Hemisphere’s clearer atmosphere – less polluted by industrial aerosols – exacerbates the issue. These aerosols reflect sunlight, providing a minor cooling effect that is less pronounced in the Southern Hemisphere. Without this counterbalance, the ocean’s heat release will be more impactful.
The Path Forward
While this modeling predicts a thermal burp even in a scenario with net-negative emissions, reducing current pollution remains paramount. The faster humanity transitions away from fossil fuels, the less CO2 will need to be removed later. As oceanographer Ric Williams emphasizes, preventing emissions is far more effective than relying solely on carbon removal technologies.
Ultimately, the Southern Ocean’s behavior underscores the planet’s intricate interconnectedness. Even successful climate mitigation efforts could be delayed by the natural inertia of Earth’s systems, making rapid and decisive action on emissions the most crucial step toward a stable future.
