Update: We have updated this analysis following further review of the scientific literature and new information on the registry. Our original analysis made two assumptions that we find warranted further examination: the amount of natural carbonation expected over the lifetime of concrete, and the relationship between injected CO₂ and natural carbonation.

Our updated analysis uses a revised benchmark for natural carbonation and as a result, the risk of over-crediting is somewhat lower. In addition, we found that, under typical conditions, CO₂ injected into concrete can represent additional storage rather than simply accelerating carbonation that would have occurred naturally. As a result, we have revised our assessment of credits from CO₂-injected concrete projects.