The findings reveal that only a small portion of the world’s geological layers can safely and effectively contain carbon dioxide (CO₂), challenging the long-standing assumption that geological storage capacity is virtually infinite.
Instead of providing silver bullet solutions for the climate crisis, the study concludes that carbon storage is a rare and finite global resource.
Underground storage reality check
For years, carbon storage has been defended as an important weapon in the fight against climate change.
By obtaining direct emissions from factories, power plants or air and trapping them deep underground, the process has promised to buy more time to decarbonise the global economy.
However, IIASA-led research has revealed that the realistic capacity for safe storage is approximately 146 billion tons of CO2.
This inconsistency arises from the way in which storage possibilities were previously calculated. Previous studies have assumed that using almost all sedimentary rock formations could be used to overlook major safety and environmental risks.
The new study carefully excluded areas that are prone to earthquakes, where groundwater is at risk of contamination, or that are too shallow or deep for reliable storage, or in sensitive ecosystems or densely populated areas.
Why does carbon storage potential shrink so sharply?
The team began by mapping sedimentary basins. This is an underground rock formation that has accumulated over millions of years and has served as a major storage candidate.
We then assessed each formation against several risk factors, including:
Potential leakage into the atmosphere. Earthquakes are at risk of being caused by underground injections. Threat to groundwater consumption supply. It is close to communities and protected areas. Technical and financial feasibility including depth and marine placement.
After applying these safety filters, the theoretical global storage pool contracted dramatically. What once thought to be almost an infinite solution has been revealed as a strictly combined resource that needs to be managed carefully.
Limited cooling capacity: only 0.7°C
The researchers then evaluated how much global warming could be reversed if all safe storage sites were used for carbon removal only and no further emissions were generated.
Answer: Just 0.7°C of cooling – a far cry from the drastic reductions once promised by carbon storage advocates.
In contrast, the risk-ignoring engineering-centric model suggests a decrease of 5°C to 6°C. The new results highlight the sharp disparity between what is technically possible and what is actually safe, sustainable and equitable to future generations.
The study also warns that removing Co2 will not cancel climate change, a simple mirror image of how emissions cause it.
Even if the temperatures on Earth drop, the Earth’s systems do not return to their previous states, leaving ecosystems and societies to deal with irreversible changes.
Geographic winners and losers
Global photographs of carbon storage are uneven. Countries with large fossil fuel industries, such as the US, Russia, China, Brazil and Australia, often have the greatest potential thanks to abandoned mines and extensive underground basins.
In contrast, regions such as India, Norway, Canada and the majority of the European Union lose a significant amount of potential storage when safety risks are taken into consideration.
However, countries including Saudi Arabia, Kazakhstan and the Democratic Republic of the Congo have scored relatively high points in safe, low-risk storage locations.
Overall, around 70% of the world’s safe storage potential is on land, with the remaining 30% offshore, with the generally high cost and risk.
Who stores carbon?
Beyond technical limitations, this study highlights ethical and political dilemmas. Countries with the highest historical responsibility for emissions often have the greatest storage potential.
This raises difficult questions of fairness. Do they need to prioritize storage for continuous pollution or maintain the capacity for global joint removal that benefits all countries?
The authors argue that carbon storage must be considered a “intergenerational resource.” The choices made today will determine not only which countries and industries can use it, but also what options remain for future generations.
Impact on global climate policy
The findings arrive at a pivotal moment for international climate planning.
Several scenarios used by the Intergovernmental Panel on Climate Change (IPCC) to guide policies run out of safe storage limits, newly calculated 2,100 years ago, and most scenarios are destroyed at 2,200.
This means policymakers can’t afford to view carbon storage as a bottomless pit of emissions. Instead, it must be treated as a finite and valuable resource. This should be reserved for the most difficult sectors and long-term carbon removal, rather than offsetting the ongoing use of fossil fuels.
Strategic use, not free pass
The key point of this research is strict. Carbon storage cannot serve as an unlimited escape hatch from the climate crisis.
Carelessly used to extend the dependence of fossil fuels can waste storage capacity within a century, and future generations will not leave a safety net.
When used wisely and combined with rapid emission reductions, when reserved for sectors with no viable alternatives, it could play a pivotal role in stabilizing the climate.
This study calls for a clear, transparent, and fair plan for how countries use storage capacity within their climate strategy, ensuring that they are managed responsibly and equitably across borders and generations.
Rare resources that demand careful stewardship
The message from the IIASA-led team is clear. Carbon storage is essential, but not infinite.
Just like rare natural resources, there is a need for careful management, international cooperation, and a long-term vision to balance safety, justice and sustainability.
With the world going well at up to 3°C of warming this century, relying solely on carbon storage cannot even return temperatures to the critical 2°C threshold set by the Paris Agreement.
The only path forward is to treat storage as a complementary tool. This is to support alternatives, deep emission reductions.
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