The feasibility of reaching gigatonne scale CO2 storage by mid-century

Abstract The IPCC Sixth Assessment Report (AR6) projects subsurface carbon storage at rates of 1–30 GtCO₂ yr⁻¹ by 2050. These projections, however, overlook potential geological, geographical, and techno-economic limitations to growth. We evaluate the feasibility of scaling up CO₂ storage using a geographically resolved growth model that considers constraints from both geology and scaleup rate. Our results suggest a maximum global storage rate of 16 GtCO₂ yr⁻¹ by 2050, contingent on the USA contributing 60% of the total. This reduces to 5 GtCO₂ yr⁻¹ if projections are constrained by government roadmaps, mostly because this limits deployment in the USA to 1 GtCO₂ yr⁻¹. These values contrast with projections in the AR6 that vastly overestimate the feasibility of deployment in China, Indonesia, and South Korea. Subsurface carbon storage can achieve gigatonne scale mitigation by mid-century, but projections should be updated to include limits from geology, geography, and rates of deployment.