New Study Finds Carbon Storage Potential Vastly Overestimated, Impacting Climate Strategies

A recent study published in Nature on September 3, 2025, reveals that the global capacity for securely storing carbon dioxide (CO₂) underground is approximately ten times lower than previously estimated, significantly impacting the projected effectiveness of carbon capture and storage (CCS) technologies in mitigating climate change.

The study, led by researchers from the International Institute for Applied Systems Analysis (IIASA), found that only about 1,460 gigatonnes of CO₂ can be safely stored in geological formations, compared to earlier estimates of around 14,000 gigatonnes. This substantial reduction is attributed to risks such as gas leakage, induced seismicity, and groundwater contamination associated with many potential storage sites. Consequently, the potential of CCS technology to reduce global warming is now projected to be limited to approximately 0.7°C, as opposed to earlier projections of 5–6°C.

"Carbon storage is often portrayed as a way out of the climate crisis. Our findings make clear that it is a limited tool," said lead author Matthew Gidden, a research professor at the University of Maryland's Center for Global Sustainability. He emphasized the "extreme importance of reducing emissions as fast and as soon as possible."

Carbon Capture and Storage (CCS) is a technology designed to capture CO₂ emissions from industrial processes and power generation, preventing them from entering the atmosphere. The captured CO₂ is then transported and stored underground in geological formations. CCS has been considered a critical tool in mitigating climate change, especially for industries where reducing emissions is particularly challenging, such as cement and steel production.

The study indicates that the potential of CCS technology to mitigate global warming is now projected to be limited to a reduction of approximately 0.7°C, compared to earlier projections of 5–6°C. This underscores the necessity of prioritizing emission reductions at the source and suggests that CCS should be reserved for sectors where decarbonization is particularly challenging, such as cement production, agriculture, and aviation.

Dr. Ben Caldecott, Director of the Oxford Sustainable Finance Group at the University of Oxford, commented on the study:

"Finite geological storage will need to be stewarded wisely, even more wisely than the paper suggests. The estimates are a very significant overestimate of what geological storage will actually be available as the economics have not been factored in. Only a fraction of that estimated will be accessible at a price society will be willing to pay."

The economic viability of CCS has been a longstanding concern. The cost of capturing and storing CO₂ varies significantly depending on the source and technology used. For instance, capturing CO₂ from natural gas processing can cost between $15 to $25 per tonne, while capturing from more diluted sources like coal-fired power plants can range from $40 to $120 per tonne. These costs do not include transportation and storage expenses.

In the United States, the CCS sector has faced challenges due to inflation and political uncertainty. High inflation, increased capital costs, and interest rates have eroded project feasibility, with developers facing 30% higher expenses. The future of funding is uncertain under President Trump, potentially impacting grants while tax credits may survive due to CCS prevalence in Republican states.

The concept of CCS has been explored for decades, with varying degrees of success. As of July 2024, commercial-scale CCS was in operation at 44 plants worldwide, capturing around 33 million tonnes of CO₂ annually. However, this represents a small fraction of global emissions.

The recent study's findings suggest that while CCS can play a role in mitigating climate change, its capacity is more limited than previously thought. This necessitates a reevaluation of reliance on CCS and emphasizes the importance of direct emission reductions and the development of alternative technologies.

In light of these findings, policymakers and industries are urged to prioritize emission reductions at the source and judiciously utilize CCS where most effective. The study underscores the need for a strategic approach to utilizing limited CO₂ storage capacity and emphasizes the importance of direct emission reductions and investment in alternative technologies.