The direct or indirect quantification of services provided by ecosystems requires the production of indicators. We investigated the construction and the use of an indicator of climate change regulation service, the so-called “carbon indicator”, with a special focus on the data that were processed to calculate and inform it (notably for forest ecosystems) and on the mechanisms that allowed this indicator to be accepted both in ecosystem services science and policy. We based our approach on a critical analysis of the documents produced by the Millenium Ecosystem Assessment (MEA), but also by the Intergovernmental Panel of Experts non Climate Change (IPCC) to relate the rationale of this indicator. We also highlighted, in the scientific literature, elements of debate and explained arguments used and spheres where this indicator has taken place. We thus identified the differences between the two processes, and analyzed to what extent innovations and indicators produced by a given process were translated in the other. The carbon indicator is based on the equivalence between CO2 and other greenhouse gases and was first produced by the IPCC. Ecosystem services assessments translated this equivalence while focusing on carbon budget, omitting most of the controversies and approximations of concern. Preexisting large scale data, notably for forest ecosystems, was also a crucial element for the recycling of this indicator by different spheres.