Integrated Assessment Models must better constrain CO2 geological storage projections

The availability of large-scale CO ₂ Geological Storage (CGS) strongly influences the feasibility and costs of ambitious climate pathways in Integrated Assessment Models (IAMs). IAMs describe transformation pathways across energy, land-use, economy, and climate systems, with CGS playing a central role in many scenarios. However, how IAMs handle CGS has faced recent criticism. Here, we examine how nine leading IAMs constrain CGS. We find high variability (> 75%) in geological storage potential limits, driven by differing treatment of regions and reliance on outdated and/or methodically inconsistent sources. Literature based cost assumptions have recently been corrected upwards and may therefore be currently too low in IAMs, while CGS growth constraints are still being developed. We define a series of recommendations for the IAM community, as well as for the geoscience and engineering community, which will improve confidence in CGS projections and wider climate change mitigation pathways.