The adoption of the Kyoto Protocol was a major breakthrough in committing industrialized countries to reduce their emissions of greenhouse gases, even if the effect is disputed. The protocol works through mechanisms that ascribe value to the environment in terms of those emissions—a numerical value based on carbon, which is then translated into a monetary value. This article reviews the different understandings of value implicated in debates about the environment seen through carbon. It does this by contrasting the values embedded in some of the various initiatives that have resulted from the Kyoto Protocol, and how they relate to the market, government control, and individual consumer morality, among other things. Controversy over carbon trading is entangled in the capacity of carbon to commensurate a wide range of human and non-human actions via their cost in emissions, which nevertheless is countered by moral differentiation.