This article addresses the challenges for companies that seek to invest in carbon abatement projects. Traditionally, such companies would address their own operations, but it might be more efficient to invest in improving the operations of a supplier or customer. By adopting a supply chain perspective on carbon abatement projects, this study proposes a way to account for activities beyond the company's boundaries. First, the proposed decisionsupport framework enables companies to define the appropriate boundaries for carbon emission measurement and abatement and identify the relevant optimisation problem. Second, this framework describes options for optimising the level of abatement effort linked to each selected action. Third, an application of the framework to the Eastman Chemical Company reveals several real-world implications, including recommendations for where to exert carbon abatement efforts in a supply chain. As this illustrative case shows, external abatement efforts can be worthwhile in practice.