Ecological modernist approaches to climate change are premised upon knowing carbon emissions. I ask how corporate environmental managers know and do carbon, i.e., shape the reality of emissions. I argue that for managers’ practical purposes carbon exists as malleable data. Based on ethnographic fieldwork over a period of 20 months in a Fortune 50 multinational corporation, I show that managers materially- discursively arrange heterogeneous entities – databases, files, paper, words, numbers – in and between office spaces, enabling them to stage emission facts as stable and singular. Employing Annemarie Mol’s work on multiplicity, I show that multiple enactments of carbon hang together not by an antecedent body (CO2) but through ongoing configurations of data practices. Disillusioning promissory economic dis- courses of ‘internalisation’, I demonstrate: Management is materially premised upon preventing purport- edly internalised carbon realities from entering capitalist core processes. This undermines carbon economics’ realist promises. Staging some carbon realities as in control is premised upon managers’ ongo- ing, reflexive, partial and always situated configuration of, e.g., standards, formal meetings or digital data practices in which humans do carbon-as-data. Carbon practices are materially-discursively aligned, form- ing a configuration. This configuration effects carbon as a malleable and locally configurable space rather than as a closed fact. Reconstructing managers’ practices as configuring carbon-as-dataspace, I argue, allows grasping adequately the contingency and constraints of managing carbon as a particular mate- rial-discursive form of environment. In conclusion I generalise the environmental management office as a space that can be configured to stage, beyond carbon, other global environments as well.