The article looks at how a system called the Clean Development Mechanism (CDM) generates carbon credits through projects that reduce emissions in developing countries. The authors focus on the issue of proving that these projects actually lead to additional emission reductions beyond what would happen naturally. They examine how the process of confirming this "additionality" works and warn about vulnerabilities to fraud. They urge for tighter oversight to maintain the credibility of future climate market systems after the Kyoto Protocol ends.