Carbon dioxide released from the burning of fossil fuels is a major concern of our times. There is now a political agreement that these emissions must decrease. So far one way forward has been to design and maintain carbon markets. As part of this process, trees in the tropics have been enrolled in peculiar transactions: actions such as reforesting a land of degraded savannah or preserving a piece of forest can produce tradable emission credits to offset against CO2 emissions in distant locations. Based on a multi-sited investigation of carbon offsetting, including fieldwork in the Congo, the paper presents a journey across different marketization sites where the enrolment of forest carbon into market exchanges can be seen to be at stake. Several operations are foregrounded, from United Nations negotiations and the measurement of carbon stocks, to business venture and legal work. The paper proposes a focus on the mundane that attends to details and frictions. This provides a deflationary story of the marketization of forest carbon, a story of contingencies and unexpected ramifications