Recomputable Carbon Evidence: A Protocol for Grading, Abstention, and Red Teaming

Product carbon footprints increasingly inform procurement, trade, finance, and public environmental claims, yet a numerical footprint can remain difficult to recompute even when it is formally documented. Existing life cycle assessment standards address goal, scope, inventory quality, and reporting, while recent work on artificial intelligence-assisted carbon footprinting addresses benchmarking, transparency, and uncertainty. Less attention has been paid to the operational point at which an automated system should refuse to issue an evidence unit, how evidence adequacy should be graded separately from environmental performance, and how independent adversarial review should govern release. This article proposes a risk-based verification protocol that combines five components: batch-level verification units; provisional evidence grades based on accepted direct measurement; deterministic rule execution with an explicit ABSTAIN outcome; portable, versioned, and revocable evidence records; and an independent Evidence Red Team with defined stop authority for high-risk releases. The protocol does not claim that cryptographic integrity establishes the truth of source data, that an evidence grade measures lower emissions, or that automation removes professional accountability. A multi-site evaluation design is specified to test false acceptance, defect escape, manual review effort, threshold gaming, independent recomputation, and the cost of adversarial governance. The contribution is a falsifiable research agenda and an implementation-ready protocol, not an empirical validation. The design is intended to support future methodological assessment and responsible commercial deployment without treating publication as a substitute for evidence.