Sub-seabed basalt formations are increasingly recognized as a significant natural mechanism for the permanent capture of carbon dioxide (CO2), offering a promising route for climate change mitigation. This geological process converts atmospheric CO2 into stable carbonate minerals through natural chemical reactions involving CO2, water, and basaltic rock. The mineralization process can occur within years, substantially reducing the risk of CO2 leakage.
Research presented at the InterPore2025 conference in May 2025 highlighted the effectiveness and potential geomechanical risks of storing CO2 within continental flood basalts. A study published in the journal Fuel in September 2025 further explored the mechanisms and technological advancements utilizing basalt as a carbon sink. These findings underscore the vast potential of sub-oceanic basalt deposits, which theoretically possess a storage capacity estimated to be in the range of 100,000 gigatons, far exceeding current global CO2 emissions. This potential was explored by the Pacific Institute for Climate Solutions (PICS) Solid Carbon project, whose geochemical simulations indicated the feasibility of gigaton-scale CO2 storage when injected directly into deep ocean basalt, where it reacts with minerals to form solid carbonate rock.
While some methods, like Iceland's CarbFix project, demonstrate rapid mineralization within two years at shallower depths, University of Calgary simulations suggest that even if mineralization takes centuries, preventing CO2 escape before completion is key. This is aided by impermeable sediment layers typically found above deep ocean aquifers. However, a study published in Nature in September 2025 offers a more conservative estimate of global CO2 storage capacity, around 1.46 trillion tonnes, factoring in broader risk factors. This revised figure suggests that even full utilization of safe storage areas might only limit global warming by approximately 0.7°C. This study focused on various storage options but noted that basalt mineralization is still in early development stages.
The economic viability and speed of scaling storage capacity remain significant challenges, as noted by experts like Kate Moran, president and CEO of Ocean Networks Canada. Despite these hurdles, basalt's inherent properties make it a compelling candidate for carbon sequestration. Basaltic rocks are rich in calcium, magnesium, and iron-bearing silicate minerals that readily react with CO2 to form stable carbonate minerals. Projects like CarbFix in Iceland have demonstrated over 95% mineralization within two years, offering a more permanent storage solution compared to gaseous forms with higher leakage risks. The U.S. Department of Energy also recognizes basalt formations as a key type of underground formation for geologic carbon storage, alongside saline formations, oil and gas reservoirs, unmineable coal seams, and organic-rich shales. Ongoing research and technological advancements continue to refine the understanding and application of basalt as a natural vault for carbon capture.