Description: The Intergovernmental Panel on Climate Change concludes that CO2 capture and storage (CCS) is critical for climate-stabilizing energy transitions. In CCS, captured CO2 is sequestered in saline aquifers within sedimentary basins. The CO2 storage capacity and the rate of injection are functions of the geology of the saline aquifer, which is uncertain. To minimize impacts of this uncertainty, CCS projects could include backup plans, such as co-locating geologic CO2 storage (GCS) sites with or near existing CO2-enhanced oil recovery (CO2-EOR) operations.