Where are the best prospects for storing large volumes of carbon dioxide in deep saline formations? And   what is the estimated CO2 storage capacity of these formations? Researchers and organizations from around the globe have spent over a decade trying to answer these questions by using a variety of different methodologies. Variability in the underlying inputs, calculation algorithms and associated uncertainty has made it challenging for CCUS stakeholders to effectively use these assessments in decision making. Colleagues from the US-China Clean Energy Research Program have recently published a thorough review of storage capacity assessments and have proposed a new hierarchical framework meant to provide consistency and clarity on this topic. This open access article led by Ning Wei of the Chinese Academy of Sciences is now available in the journal Frontiers in Earth Science: https://www.frontiersin.org/articles/10.3389/feart.2021.777323/full