3 July 2025A key factor undermining the credibility of carbon offsets is the evaluation of project baselines and their impact. The ex-ante scenarios constructed by project developers in accordance with rules set by certification schemes have been challenged by ex-post evaluations from scientists, who frequently document cases of credit allocations that overestimate the actual emission reductions. Increasing credibility requires methodologies that reliably measure project outcomes and prevent over-crediting – an objective that ex-post evaluations may be well suited to achieve. We explore how systematic ex-post evaluations could restore credibility to certification schemes in the voluntary carbon market (VCM).