Rate and growth limits and the role of geologic carbon storage in meeting climate targets

CO ₂ capture and storage (CCS) in geologic reservoirs is expected to play a large role in low-emissions scenarios that comply with the Paris Agreement, especially its aspirational 1.5 ⁰C goal. Yet these scenarios are often overly optimistic regarding near-term CCS deployments. They have also failed to consider regional differences in capacity to deploy large-scale subsurface CO ₂ injection. Here, we quantify a range of regionally explicit scalability rates for CCS and use these to update a leading integrated energy-economy model. We then evaluate implications for Paris-compliant emissions trajectories, energy mix, use of rate-limited storage capacity, and mitigation costs. Under limited CCS ramp-up rates, deployment in 2100 could be reduced by a factor of 5, with a factor of 20 reduction at mid-century under a below 2 ⁰C emissions trajectory. Residual use of oil, gas, and coal in a below-2⁰C scenario could also be reduced by nearly 50%. However, sustained efforts to rapidly scale CCS could reduce transition costs by nearly $12 trillion (20%) globally, with cost reductions most heavily concentrated in regions such as China and India. Delaying mitigation in anticipation of unconstrained CCS scaling that in fact proceeds far more slowly results in + 0.15 ⁰C higher temperatures in 2100. In contrast, aggressive emissions cuts in anticipation of slower CCS scaling that subsequently far exceeds expectations results in lower peak temperatures and help de-risk efforts to meet the 1.5 ⁰C goal.