Massive hidden heat ‘burp’ building in Southern ocean could reignite global warming

Southern Ocean’s Hidden ‘Heat Burp’ Could Warm the Planet for Another Century (Image: Canva)

For over a century, the Southern Ocean has silently absorbed vast amounts of carbon dioxide and heat from human activities. But scientists warn that once we finally stop burning fossil fuels, the ocean could release that trapped heat, causing another century of global warming.

What does the new study suggest?
A team of climate scientists from Germany predicts a significant “burp” of heat from the Southern Ocean after global emissions eventually fall. Their findings, published in AGU Advances, suggest that even after the world reaches net-negative carbon emissions, oceanic heat release could spark a renewed warming phase lasting over a hundred years.

The researchers from the GEOMAR Helmholtz Centre for Ocean Research, led by biogeochemist Ivy Frenger, used a climate framework combining atmospheric, oceanic and biospheric models. Their simulation assumes that carbon dioxide emissions rise for the next 70 years before peaking and are then sharply reduced, leading to a long period of cooling.

Why would the Southern Ocean release heat?
Under current warming, the ocean stores heat as deep waters mix with warmer layers above. At the same time, the loss of reflective sea ice allows more solar radiation to penetrate and be absorbed. Even when atmospheric carbon dioxide levels begin to drop, the ocean continues storing heat because surface temperatures cool slowly.

According to the model, after several centuries of cooling, the Southern Ocean releases this accumulated heat back into the atmosphere. “We find, after several centuries of global cooling under negative CO₂ emissions, global atmospheric warming that is unrelated to CO₂ emissions and is caused by ocean heat release,” Frenger’s team explained.

Global surface air temperature (solid line), land air temperature (dotted line), and sea surface temperature (dashed line) are shown as anomalies relative to preindustrial levels. The grey shading highlights the period representing the ‘burp’. (Image: Frenger et al., AGU Advances, 2025)

How severe could this rebound warming be?
The researchers say the rate of warming would be comparable to the average rise seen during the industrial era and could persist for more than a century. The impact, though, would not be uniform. The warming would be most pronounced in the Southern Hemisphere and would disproportionately affect developing countries most susceptible to climate change.

So what does this have to do with climate action?
These results contradict the traditional assumption that global temperatures would decline rapidly once emissions begin to subside. The research indicates that the planet might keep warming for hundreds of years even after going net-negative.

The researchers add that this might redefine the way policymakers and scientists are projecting long-term climate recovery.

The message is clear: the longer humanity delays reducing fossil fuel use, the more intense this delayed ocean “burp” of heat may become.