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The world’s oceans have long served as one of Earth’s most important climate regulators, quietly absorbing billions of tonnes of carbon dioxide released by human activity. Yet new scientific findings suggest that one of nature’s most powerful weather systems—tropical cyclones—may be dramatically altering that balance in ways scientists are only beginning to understand.
A new international study has revealed that tropical cyclones currently contribute to the release of carbon from the ocean into the atmosphere. However, as global temperatures continue to rise, researchers warn that this relationship may soon reverse. By as early as 2035, tropical cyclones could begin increasing carbon uptake by the ocean instead, a shift that may sound beneficial at first glance but could intensify ocean acidification and place even greater stress on marine ecosystems.
The findings add another layer of complexity to the climate crisis, highlighting how warming oceans are changing not only weather patterns but also the fundamental processes that govern Earth’s carbon cycle.
The Ocean’s Critical Role in Climate Regulation
The ocean absorbs approximately 20–30% of human-generated carbon dioxide emissions each year, making it one of the planet’s most effective natural carbon sinks. Without this enormous buffering capacity, atmospheric carbon dioxide concentrations would be significantly higher, accelerating global warming even further.
Carbon moves continuously between the atmosphere and the ocean through a process known as air-sea carbon exchange. When the ocean absorbs more carbon dioxide than it releases, it acts as a carbon sink. When it releases more than it absorbs, it becomes a carbon source.
Scientists have spent decades studying how rising temperatures affect this balance, but the role of tropical cyclones has remained largely uncertain due to the difficulty of collecting observations during extreme weather events.
Now, researchers from the National University of Defense Technology, the Chinese Academy of Sciences, the NSF National Center for Atmospheric Research, and the GEOMAR Helmholtz Centre for Ocean Research Kiel have assembled one of the most comprehensive global datasets ever created to examine how tropical cyclones influence ocean carbon exchange.
Their results suggest these storms play a much larger role in the global carbon budget than previously understood.
How Tropical Cyclones Influence Carbon Exchange
Tropical cyclones generate intense winds capable of dramatically disturbing the ocean’s surface.
When a cyclone passes over warm ocean waters, powerful winds increase the transfer of carbon dioxide from the sea into the atmosphere. This process effectively turns affected regions into temporary carbon sources.
However, cyclones also trigger another important mechanism.
As storms churn the upper layers of the ocean, colder water from deeper depths rises to the surface. These so-called “cold wakes” cool sea surface temperatures and enhance the ocean’s ability to absorb carbon dioxide after the storm has passed.
The interaction between these competing processes determines whether a cyclone ultimately contributes to carbon release or carbon uptake.
According to the study, tropical cyclones currently result in a net release of carbon from the ocean. Yet the magnitude of this effect has been steadily decreasing over recent decades due to climate-driven changes in ocean structure.
Climate Change Is Altering the Equation
Researchers found that between 1993 and 1997, tropical cyclones accounted for approximately 16% of global annual ocean carbon flux associated with these storm events.
By the period between 2016 and 2020, that figure had fallen to around 4.5%.
The primary reason lies beneath the ocean surface.
Global warming is causing surface waters to heat faster than deeper waters, increasing what scientists call ocean stratification. This creates a stronger temperature contrast between warm surface layers and colder subsurface waters.
As a result, when tropical cyclones churn the ocean, they generate more pronounced cooling effects than they did decades ago. These stronger cold wakes increase carbon dioxide absorption following storms, gradually offsetting the initial carbon release caused by cyclone winds.
The researchers concluded that if greenhouse gas emissions remain high, this trend could continue until tropical cyclones transition from being net carbon sources to net carbon sinks around 2035.
The Hidden Danger of Increased Carbon Uptake
At first glance, greater carbon absorption by the ocean may appear to be positive news for climate mitigation.
Yet scientists caution that increased carbon storage in seawater carries significant ecological consequences.
When carbon dioxide dissolves in seawater, it forms carbonic acid, lowering the ocean’s pH and contributing to ocean acidification. This chemical shift reduces the availability of carbonate ions that many marine organisms rely upon to build shells and skeletons.
Coral reefs, shellfish, plankton, and numerous other marine species are particularly vulnerable.
Ocean acidification has already been identified as one of the most serious threats facing marine biodiversity. The prospect of tropical cyclones accelerating ocean carbon uptake could intensify these pressures in coming decades.
Researchers warn that the combined effects of warming waters, stronger storms, declining oxygen levels, and increasing acidity may create cascading impacts throughout marine food webs.
Implications for Marine Ecosystems
Marine ecosystems depend on a delicate balance of temperature, chemistry, and nutrient availability.
Changes in carbon cycling can influence everything from phytoplankton productivity to fish populations and coral reef health.
Coral reefs are already experiencing widespread bleaching events due to rising ocean temperatures. Additional acidification could further weaken reef structures, reducing their ability to support marine biodiversity and protect coastlines from storms.
Shell-forming organisms such as oysters, mussels, and certain plankton species may also struggle to survive in increasingly acidic waters.
Because these organisms form the foundation of many marine food chains, disruptions could ripple across entire ecosystems and affect fisheries that millions of people depend upon for food and livelihoods.
Scientists increasingly view ocean acidification as a parallel crisis to global warming—one that receives far less public attention despite its potentially profound consequences.
A Reminder of the Ocean’s Climate Limits
The study also underscores a broader concern among climate researchers: the ocean’s capacity to protect humanity from its own emissions is not limitless.
For decades, oceans have buffered the impacts of fossil fuel combustion by absorbing vast quantities of heat and carbon dioxide. Yet this service comes at a cost.
Rising ocean temperatures, changing circulation patterns, acidification, deoxygenation, and biodiversity loss are all signs of mounting stress on marine systems.
Recent reports have highlighted significant uncertainties surrounding the future strength of the global ocean carbon sink. Scientists fear that continued warming could alter ocean processes in ways that make climate projections increasingly difficult.
The new cyclone research adds another variable to an already complex picture.
Whether tropical cyclones ultimately become net contributors to ocean carbon storage will depend heavily on future greenhouse gas emissions. Researchers emphasize that rapid emissions reductions could delay or reduce the magnitude of the projected shift.
The Future Depends on Emissions Decisions Today
Perhaps the most important conclusion from the study is that the future role of tropical cyclones is not predetermined.
Researchers found that scenarios involving aggressive emissions reductions slow the transition considerably, potentially delaying significant changes in cyclone-driven carbon exchange until much later in the century.
In contrast, continued high emissions could accelerate the transformation of ocean carbon processes and intensify acidification risks for marine ecosystems worldwide.
As policymakers prepare for another decade of increasingly severe climate impacts, the findings serve as a reminder that climate change affects far more than temperature records and extreme weather events. It is reshaping the invisible systems that regulate life on Earth, including the vast oceans that have long shielded humanity from the full consequences of its carbon emissions.
The challenge now is ensuring that those natural defenses are not pushed beyond their limits.
References
- Phys.org – Tropical cyclones now release ocean carbon, but warming could flip role by 2035
https://phys.org/news/2026-05-tropical-cyclones-ocean-carbon-flip.html - Nature Geoscience – Reduction of tropical cyclone-induced ocean carbon outgassing since 1993
https://www.nature.com/articles/s41561-026-01985-4 - NOAA Geophysical Fluid Dynamics Laboratory – Global Warming and Hurricanes
https://www.gfdl.noaa.gov/global-warming-and-hurricanes/ - IOC-UNESCO Report Coverage – Ocean carbon blind spot may skew climate forecasts
https://phys.org/news/2026-02-ocean-carbon-skew-climate.html - Nature Climate and Atmospheric Science – Extratropical storms induce carbon outgassing over the Southern Ocean
https://www.nature.com/articles/s41612-024-00657-7 - PNAS – Resolved tropical cyclones trigger CO₂ uptake and reshape ocean carbon cycling
https://www.pnas.org/doi/10.1073/pnas.2506103122 - Climate Central – Climate Shift Index: Tropical Cyclones
https://www.climatecentral.org/climate-shift-index-tropical-cyclones - NOAA Ocean Acidification Program – Ocean Acidification Resources
https://oceanacidification.noaa.gov
