The article explores how the Clean Development Mechanism (CDM) measures the success of projects that reduce greenhouse gas emissions. They compare project emissions with a hypothetical "business-as-usual" scenario to calculate Certified Emission Reductions (CERs). The accuracy of these comparisons is essential for the credibility of the CDM. By analyzing early methodologies submitted to the CDM Executive Board, the study reveals that determining baselines and additionality is crucial for attracting investments and public support in climate projects.