A global study led by the International Institute for Applied Systems Analysis (IIASA) has redrawn the map of underground carbon storage potential.
The findings reveal that only a fraction of the world’s geological formations can safely and practically hold carbon dioxide (CO₂), challenging long-held assumptions that geological storage capacity is virtually limitless.
Instead of offering a silver-bullet solution to the climate crisis, the study concludes that carbon storage is a scarce and finite global resource – one that could only reverse global warming by up to 0.7°C, far less than industry projections of 5–6°C.
A reality check on underground storage
For years, carbon storage has been championed as a crucial weapon in the fight against climate change.
By capturing CO₂ emissions from factories, power plants, or directly from the air, and locking them deep underground, the process promised to buy humanity more time to decarbonise the global economy.
But the IIASA-led research reveals that the realistic capacity for safe storage is around 1,460 billion tonnes of CO₂ – almost ten times smaller than widely cited industry estimates of more than 14,000 billion tonnes.
This discrepancy arises from the way storage potential has been calculated in the past. Previous studies assumed that nearly all sedimentary rock formations could be used, overlooking major safety and environmental risks.
The new research carefully excluded areas prone to earthquakes, at risk of contaminating groundwater, too shallow or too deep for reliable storage, or located in sensitive ecosystems and densely populated regions.
Why carbon storage potential shrinks so sharply
The team began by mapping sedimentary basins – underground rock layers that have built up over millions of years and serve as prime storage candidates.
They then evaluated each formation against several risk factors, including:
- Potential CO₂ leakage back to the atmosphere.
- Earthquake risks triggered by underground injection.
- Threats to groundwater supplies.
- Proximity to communities and protected areas.
- Technical and financial feasibility, including depth and ocean placement.
After applying these safety filters, the theoretical global storage pool contracted dramatically. What once appeared to be an almost infinite solution was revealed as a tightly bound resource that must be carefully managed.
Limited cooling power: Only 0.7°C
The researchers then assessed how much global warming could be reversed if every safe storage site were used exclusively for carbon removal, with no further emissions produced.
The answer: just 0.7°C of cooling – a far cry from the sweeping reductions once promised by carbon storage advocates.
By contrast, engineering-focused models that ignore risks have suggested reductions of 5°C to 6°C. The new results highlight the sharp divide between what is technically conceivable and what is actually safe, sustainable, and fair to future generations.
The study also warns that removing CO₂ does not undo climate change in a simple mirror image of how emissions cause it.
Even if global temperatures drop, the Earth’s systems may not return to their previous state, leaving ecosystems and societies to deal with irreversible changes.
Geographic winners and losers
The global picture of carbon storage is uneven. Countries with large fossil fuel industries, such as the United States, Russia, China, Brazil, and Australia, possess the greatest potential, often thanks to disused mines and extensive underground basins.
By contrast, regions like India, Norway, Canada, and much of the European Union lose significant amounts of potential storage once safety risks are accounted for.
Nations including Saudi Arabia, Kazakhstan, and the Democratic Republic of the Congo, however, score relatively high on safe and low-risk storage sites.
Overall, around 70% of the world’s safe storage potential lies onshore, with the remaining 30% offshore, where costs and risks are generally higher.
Who gets to store carbon?
Beyond technical limits, the study highlights ethical and political dilemmas. Countries with the greatest historical responsibility for emissions often also have the largest storage potential.
This raises difficult questions of fairness: should they prioritise storage for their own ongoing pollution, or preserve capacity for global CO₂ removal that benefits all nations?
The authors argue that carbon storage must be seen as an ‘intergenerational resource.’ Choices made today will determine not only which nations and industries can use it, but also what options remain for future generations.
Implications for global climate policy
The findings arrive at a pivotal moment for international climate planning.
Some scenarios used by the Intergovernmental Panel on Climate Change (IPCC) to guide policy would exhaust the newly calculated safe storage limit before 2100, with most scenarios breaching it by 2200.
This means policymakers cannot afford to see carbon storage as a bottomless pit for emissions. Instead, it must be treated as a finite and valuable resource – one that should be reserved for the hardest-to-abate sectors and long-term carbon removal rather than for offsetting ongoing fossil fuel use.
Strategic use, not a free pass
The key takeaway of the study is stark: carbon storage cannot serve as an unlimited escape hatch from the climate crisis.
If used carelessly to prolong fossil fuel dependence, storage capacity could be squandered within a century, leaving future generations with no safety net.
If used wisely, paired with rapid emissions cuts and reserved for sectors without viable alternatives, it could still play a pivotal role in stabilising the climate.
The study calls for nations to outline clear, transparent, and fair plans for how they intend to use storage capacity within their climate strategies, ensuring it is managed responsibly and equitably across borders and generations.
A scarce resource demanding careful stewardship
The message from the IIASA-led team is unambiguous: carbon storage is essential, but it is not infinite.
Like any scarce natural resource, it requires careful stewardship, international cooperation, and a long-term vision that balances safety, justice, and sustainability.
With the world on track for up to 3°C of warming this century, relying solely on carbon storage would not even return temperatures to the critical 2°C threshold set in the Paris Agreement.
The only path forward, the study underscores, is to treat storage as a complementary tool – supporting, not substituting, deep and immediate emissions reductions.
