A Prudent Planetary Limit for Carbon Storage: Why the World Must Treat Subsurface Space as a Finite Resource

Redacción HC
12/09/2025

Carbon capture and storage (CCS) has long been championed as a cornerstone of global climate strategies. By injecting carbon dioxide (CO₂) into deep geological formations, the hope is to lock it away for centuries, reducing atmospheric concentrations and mitigating global warming. Yet, while the fossil fuel industry has painted a picture of near-limitless underground storage potential, new research published in Nature suggests that our “geological pantry” is far smaller than previously assumed.

A team of scientists led by Matthew J. Gidden at the International Institute for Applied Systems Analysis (IIASA) has introduced the idea of a “prudent planetary limit” for geologic CO₂ storage. Their study provides a much-needed reality check: only about 1,460 gigatonnes (Gt) of CO₂ can be safely and responsibly stored worldwide, a figure far below earlier estimates ranging from 10,000 to 40,000 Gt.

Why Geological Storage Matters

The Paris Agreement requires steep reductions in greenhouse gas emissions, and many pathways to net zero by mid-century assume a heavy reliance on CCS. The technology is seen as essential not only for decarbonizing industries like cement and steel but also for achieving “negative emissions” by removing CO₂ directly from the atmosphere.

However, the new research questions the assumption of unlimited storage space. Safe storage is not just about finding rock cavities—it requires avoiding populated areas, protecting aquifers, and ensuring geological stability over thousands of years. In other words, not all underground space is usable.

A Risk-Based Assessment

Unlike earlier optimistic projections, Gidden and colleagues applied a spatially explicit risk framework. They excluded zones near critical infrastructure, urban areas, and protected ecosystems. They also considered the depth, pressure, and geological characteristics necessary for secure containment.

The analysis revealed significant geographical differences. While fossil-fuel-producing nations may possess larger robust storage areas, the distribution is uneven, raising geopolitical and ethical questions about access and responsibility. The study also modeled the potential climatic benefit: even if the entire safe storage capacity were used for carbon removal, global temperatures might only drop by about 0.7 °C—important, but insufficient to fully counterbalance unchecked emissions.

Key Findings

• Planetary limit: ~1,460 GtCO₂, with uncertainty between 1,290–2,710 Gt.
• Climate benefit: Maximum cooling potential of 0.7 °C if all capacity were used.
• Infrastructure gap: Current global CCS operations handle just 49 MtCO₂ annually, with 416 MtCO₂ in the pipeline—orders of magnitude below what would be needed.
• Risk of depletion: If fossil emissions remain high, available storage could be exhausted before 2200.

As the authors emphasize, “assuming storage is unlimited risks locking humanity into a dangerous overreliance on CCS.”

Implications for Policy and Society

This research reframes CCS not as an infinite solution but as a scarce intergenerational resource. Policymakers must make tough choices: Should storage be prioritized for hard-to-abate industries or reserved for future atmospheric removals? Should governance frameworks allocate storage equitably across nations?

The findings also caution against using CCS as a license to delay emissions cuts. Renewable energy expansion, energy efficiency, and nature-based solutions remain critical pillars of mitigation. CCS can complement these strategies but cannot replace them.

For the public, the message is clear: carbon storage is not a silver bullet. Instead, it should be treated as one of several limited tools in the broader climate action toolbox.

A Call to Action

1. National planning: Integrating storage limits into climate strategies.
2. International governance: Ensuring fair distribution and intergenerational justice.
3. Stronger regulation: Monitoring sites to prevent leakage and protect water sources.
4. Investment in alternatives: Scaling nature-based removals and emissions reductions to reduce pressure on storage capacity.

By shifting the conversation from “how much CO₂ can we pump underground?” to “how wisely should we use this finite space?”, the research sets a new benchmark for realistic climate planning.

Topics of interest

Climate