Banking on Supply Chain Decarbonisation: A Case Study on Scope 3 Emissions Management in Purchased Goods and Services at BNY

Carbon accounting methods for purchased goods and services were designed around supply chains that produce physical things. Financial institutions do not have such supply chains, and the resulting mismatch has left Scope 3 Category 1 among the least consistently reported categories in the sector, despite Scope 3 accounting for the substantial majority of financial sector emissions. This paper examines Category 1, Purchased Goods and Services (PG&S), through a case study of BNY, a global custodian bank whose supply chain is composed almost entirely of purchased services. Benchmarking across a peer group of custodians and universal banks establishes that PG&S disclosure is fragmented and that BNY does not currently carry the category into its primary sustainability reporting. Publicly disclosed expenditure indicates that its purchased inputs are concentrated in technology and professional services, with technology both the largest and the fastest growing component. A comparative review of greenhouse gas standards identifies the GHG Protocol, PCAF, and TCFD as the most relevant frameworks for the sector, though none is designed for service-heavy institutions. Drawing on a high-level internal review of BNY's calculation approach and supplier data landscape, the paper argues that of the four calculation methodologies the GHG Protocol specifies for this category, the hybrid approach offers the most workable balance between accuracy and data availability, that location-based emission factors provide a defensible baseline where spend-based estimation is unavoidable, and that market-based factors should be applied only selectively and under stated conditions. Supplier maturity emerges as the variable governing which methods are available in practice. Supplier engagement, procurement design, and contractual mechanisms are assessed as levers, while the evidence base for supply chain mapping is found to derive predominantly from goods-heavy sectors and to transfer only selectively to service supply chains. The paper concludes that effective management of PG&S emissions depends less on any single framework or technology than on combining pragmatic data solutions with supplier partnerships, procurement choices, and sustained institutional commitment.