With CBAM's definitive period in force, EU importers face materially heavier obligations: beyond embedded-emission accounting they must settle carbon costs against certified carbon-content data, and the lenient 'default value' allowance of the transition phase is gradually narrowing. For bulk petrochemical transshippers this means carbon data can no longer be a year-end roll-up — it must sit at the level of every shipped batch. SNSUC's response is 'per-batch PCF plus blockchain fingerprint'. At the warehousing stage we capture process route, energy use and transport distance to compute that batch's product carbon footprint; a browser-side SHA-256 then produces a tamper-evident fingerprint digest binding cargo title, batch and carbon data together. Downstream EU importers can recompute the fingerprint independently with public algorithms, free of any centralised system, verifying the batch's embedded emissions. The value is swapping trust cost for computation cost: cross-border mutual recognition rests on publicly verifiable maths rather than a single institution's endorsement. Across SNSUC's 13 business categories, carbon compliance is moving from passive filing to active title attestation — a new piece of transshipment infrastructure.