The United Nations Framework Convention on Climate Change (UNFCCC) Conference of the Parties (COP) in Marrakech drafted a legal and institutional structure to govern various market-based mechanisms to limit greenhouse gas (GHG) emissions. This governance instrument incorporated both economic and environmental considerations at every stage of the decision-making process. The Marrakech Accords operational guidelines govern three alternative market-based approaches: Clean Development Mechanism; Joint Implementation; and Emissions Trading. The Marrakech Accords require the development of principles and rules for measuring emission baselines and additionality which define what is a valid GHG emission reduction, the degree sustainability influences project approval, and overall transparency. Several standards have been proposed. These are analyzed and compared in this article. To date, the WWF Gold Standard offers the most efficient and commercially viable methods to achieve global sustainability.