Climate change warning: Ocean's carbon-absorbing power may bounce back if we act NOW

A new study shows the Southern Ocean could regain its carbon-absorbing ability as the ozone hole heals but only if greenhouse gas emissions drop quickly. Rising emissions could overwhelm this recovery despite ozone layer repair.

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A new scientific study has found that the negative impact of the ozone hole on the Southern Ocean’s ability to absorb carbon could be reversed—but only if global greenhouse gas (GHG) emissions drop quickly.

The study, led by the University of East Anglia (UEA) in the UK, looked at how changes in the atmosphere have affected the Southern Ocean, which plays a major role in fighting climate change. Even though it covers only a small part of Earth, this ocean absorbs a large share of carbon dioxide from the atmosphere, helping reduce the effects of global warming.

Researchers from UEA and the National Centre for Atmospheric Science (NCAS) wanted to understand how ozone depletion and rising GHG emissions influence the ocean's circulation, which in turn affects how much carbon it can take in. Their findings were published in Science Advances.

“The good news is that the damage from the ozone hole is reversible,” said Dr Tereza Jarnikova, lead author of the study and a researcher at UEA’s Tyndall Centre for Climate Change Research. “But that’s only true if we follow a low-emissions pathway. If emissions continue to rise, the damage won’t undo itself.”

In the 20th century, the hole in the ozone layer caused stronger winds over the Southern Ocean. These winds pulled carbon-rich water from deep below the surface, making it harder for the ocean to absorb carbon from the air. This led to a decline in carbon uptake, meaning more carbon stayed in the atmosphere, worsening climate change.

However, as the ozone hole starts to heal—thanks to the 1987 Montreal Protocol, which banned ozone-depleting chemicals—these strong winds could weaken. The study suggests this would allow the ocean to take in more carbon again, but only if GHG emissions are kept in check.

Using the UK’s Earth system model (UKESM1), the scientists simulated three ozone scenarios between 1950 and 2100:

• A world where the ozone hole never opened.
• A realistic world, where the ozone hole formed but then began to heal.
• A scenario where the ozone hole stayed the same size as in 1987.

They also modeled two levels of future emissions, low and high, to see how ocean circulation and carbon uptake would change. The results showed that in the future, GHG emissions, not ozone, will be the main force controlling ocean winds and carbon absorption.

While the Southern Ocean’s role as a carbon sink remains vital, the study warns that under high emissions, even a fully healed ozone layer won’t be enough to restore its full carbon-absorbing power.

The study shows that the future is uncertain. While the ozone hole’s impact on ocean winds is expected to weaken, the impact of greenhouse gas emissions will grow stronger. This means that even as the ozone layer recovers, rising greenhouse gases could still increase wind strength, continuing to disturb the ocean’s ability to store carbon.

In short, the ocean might face a new wave of disruption—this time from greenhouse gases rather than ozone loss.

The study also found that ocean circulation changes will have less effect on carbon uptake in the future than in the past. That’s because the ocean’s structure is shifting, with carbon becoming more evenly spread between the surface and deep waters.

Why this study matters

Understanding how much carbon the Southern Ocean can absorb in the future is crucial for climate planning. The Southern Ocean is one of the Earth’s largest carbon sinks. If its ability to store carbon drops further, more carbon will stay in the atmosphere, speeding up global warming.

This study highlights how global cooperation on climate policies, like the Montreal Protocol, has already helped in healing the ozone layer. But it also shows that climate action must continue, especially in cutting greenhouse gas emissions, to protect the planet’s natural systems.

Another key takeaway: ocean circulation changes will matter less in the future because the balance of carbon between the deep sea and surface waters will shift due to warming.

The study provides an urgent message: cutting emissions now is essential to protect the ocean’s ability to slow down climate change.