Many countries, including Canada, have pinned part of their climate strategy on underground carbon storage to keep greenhouse gases out of the atmosphere. However, new research published in Nature casts doubt on the long-term feasibility of this approach. The study, conducted by an international team of researchers from the U.K., Austria, and the U.S., assessed risks often overlooked in traditional analyses and concluded that safe underground storage is far more limited than previously believed.
The researchers estimated that only about 1,460 billion tonnes of carbon dioxide can be securely stored underground worldwide, compared with earlier projections of nearly 12,000 billion tonnes. This sharp downgrade means that even using all safe sites would reduce global warming by just 0.7°C, much less than the six degrees some earlier models suggested. This finding reframes carbon storage capacity as a scarce resource, one that governments must allocate carefully in their climate planning.
Canada, the U.S., and Europe are investing heavily in carbon capture and storage (CCS). Ottawa has introduced a tax credit worth up to $5.7 billion by 2028, while Washington and Brussels are running similarly ambitious subsidy programs. The problem, experts warn, is timing. Emissions remain so high that the window for effective deployment of geologic storage is closing rapidly. Rob Anex, a professor at the University of Wisconsin–Madison, cautioned that while storage potential exists, the speed and scale required to implement it may soon outstrip feasibility.
The study also diverged from conventional engineering estimates by factoring in risks such as proximity to population centers, sensitive ecosystems, protected wildlife zones, and seismic hazards. Researchers limited storage depth to 2.5 kilometers, arguing that current technology makes deeper storage unrealistic. Some experts, like Anna Littlefield from the Colorado School of Mines, contend this boundary may be too conservative given technological advances. Others, like Kate Moran of Ocean Networks Canada, point to alternative methods such as storing CO₂ in basalt beneath the seabed, where it mineralizes into solid form and minimizes leakage risk. The Cascadia Basin alone could hold an estimated 200 gigatons, underscoring the promise of unconventional solutions.
Yet cost and infrastructure remain immense hurdles. Scaling up storage would require vast pipelines and transport systems, raising both capital demands and public opposition. Anex stressed that the financial burden competes with other pressing social needs, making rapid build-out “almost unimaginably expensive.” Even if the geological space is technically available, the bigger issue is whether projects can be proven effective and secure at industrial scale. Pilot initiatives in Canada and abroad have shown mixed results, fueling skepticism about whether CCS can ever be more than a marginal solution.
Economist Dave Sawyer of the Canadian Climate Institute highlighted that while the study reduces the estimate of available carbon storage capacity, it still confirms that significant potential exists. The central challenge, he emphasized, lies in proving the technology works reliably. For now, the industry is struggling to bring successful projects online, not managing excess demand for storage sites.
Finally, the study raises doubts about the “overshoot” theory—the hope that humanity can temporarily exceed the 1.5°C warming limit and later return below it by deploying CCS. Lead author Matthew Gidden warned that if there is a hard ceiling on carbon storage capacity, then future reliance on this technology to reverse warming may be misguided. With the world already 1.3°C above pre-industrial levels, the findings underscore the urgency of immediate emission reductions rather than overconfidence in uncertain storage solutions.
In sum, the research reframes carbon storage capacity as constrained, costly, and fraught with risks. While it remains a valuable tool in the climate arsenal, it is unlikely to serve as the sweeping fix once imagined.
https://www.cbc.ca/news/science/carbon-storage-underground-1.7624319