Two of the largest corporate buyers in carbon markets moved in the same direction this week, and the direction is book and claim. Amazon is expanding its carbon credit service to offer sustainable aviation fuel (SAF) inset credits, according to Carbon Pulse, while Microsoft completed the first verified maritime emissions reduction transaction through the Roundtable on Sustainable Biomaterials (RSB) Book and Claim registry, in a pilot with Danish shipper NORDEN. For companies struggling with Scope 3 targets, the message is that chain-of-custody instruments for low-carbon fuels are graduating from pilot paperwork into procurement channels run by mainstream counterparties.
What Actually Happened
The Amazon development is incremental but telling. The company’s carbon credit service, built on the Sustainable Exchange hub it launched in 2024, began selling what it calls high-integrity, science-based credits in 2025, restricted to US supply chain partners, enterprise customers and Climate Pledge signatories that meet eligibility conditions: net-zero targets across scopes 1, 2 and 3, regular emissions measurement and reporting, and decarbonization strategies aligned with climate science. In February 2026 Amazon added lower-carbon fuel inset credits, generated by producing alternatives such as renewable diesel and biodiesel, alongside super-pollutant refrigerant destruction credits. SAF insets are the next category in that sequence, extending the fuel-inset model from road freight to aviation.
The Microsoft transaction is a first of a different kind. NORDEN has become the first maritime carrier to issue and deliver verified emissions reductions through the RSB Book and Claim system, with Microsoft as the buyer. NORDEN first had to obtain RSB Book and Claim trader certification, and RSB adapted a framework it had previously built for aviation to maritime carriers. When the two companies announced the collaboration in 2025, they said the pilot could cut Microsoft’s maritime Scope 3 emissions by nearly 10,000 tonnes of CO2e over three years. This week’s delivery puts those reductions on a registry rather than in a bilateral contract.
Why Book and Claim, and Why Now
The structural problem both deals address is the same: the physical supply of low-carbon fuel does not line up with where demand for emissions cuts sits. Only about 8% of the world fleet by tonnage is equipped to run on alternative fuels, and shipping greenhouse gas emissions rose 5% in 2024, according to figures cited by the UN Conference on Trade and Development, with longer voyages driven by geopolitical rerouting adding to the total. The International Maritime Organization estimates shipping produced 1.056 billion tonnes of CO2 in 2018, roughly 2.89% of global anthropogenic emissions.
A buyer whose cargo moves through ports without SAF or biofuel supply cannot decarbonize that transport physically, whatever its budget. Book and claim separates the environmental attribute from the physical molecule: the carrier burns the cleaner fuel where it is operationally sensible, documents the reduction, and sells the verified attribute to a customer elsewhere in the value chain. NORDEN says its biofuel solutions, usable as blends or as B100, deliver emissions reductions of up to 80 to 90% depending on fuel and application.
For Microsoft the logic is arithmetic. The company reported 20.29 million tonnes of CO2e across scopes 1, 2 and 3 in FY2025, 25% higher than the 16.21 million tonnes a year earlier, with data center growth the main driver. Scope 3 accounted for 85.82% of the total, and was already 26% above its 2020 baseline in FY2024. Upstream transportation and distribution is only 3.66% of that Scope 3 footprint, but it is one of the few slices where a verified instrument now exists.
Not an Offset, and That Is the Point
Both Amazon and NORDEN are careful to frame these instruments as insets rather than offsets: reductions generated inside the same sector and value chain where the buyer’s emissions occur, claimed against Scope 3 inventories rather than as compensation for them. The distinction matters for claims integrity. Corporate net-zero frameworks have become steadily more skeptical of outsourcing reductions to unrelated projects, and an inset tied to the buyer’s actual freight activity is easier to defend in an assurance process than a generic avoided-emissions credit. NORDEN’s COO Anne Jensen framed the appeal as reaching emissions “embedded deep within global supply chains, where they often have little visibility or direct influence.”
The verification layer is what turns a marketing concept into an accounting instrument. RSB plans to update its Book and Claim Chain of Custody procedure to support broader maritime adoption, which suggests the registry expects volume beyond a single flagship pilot. Microsoft’s market development senior manager Bella Horstmann described the collaboration as evidence that companies “don’t need to wait to start reducing their shipping emissions in a verified and meaningful way.”
What Buyers and Developers Should Watch
Three markers will show whether this week was a milestone or a press cycle. First, whether Amazon’s SAF inset offering attracts volume from the Climate Pledge and supplier base it is gated to, since a curated channel with eligibility screens is exactly the distribution model that could normalize insets without opening the door to low-quality claims. Second, whether RSB’s chain-of-custody update and competing registries converge on common rules for maritime book and claim, because fragmented attribute accounting is the fastest way to reproduce the double-counting fights that dogged the offset market. Third, how greenhouse gas accounting bodies treat book and claim in Scope 3 guidance, which will ultimately decide whether these instruments count toward science-based targets or remain voluntary extras.
For buyers, the practical takeaway is that credible Scope 3 instruments for transport now exist in both aviation and shipping, but supply is thin and registry infrastructure is still being written. Early participation buys learning and, in NORDEN’s model, a choice of reduction levels matched to budget. For fuel producers and carriers, the signal is that attribute revenue is becoming bankable: certification as a book and claim trader is emerging as a commercial asset in its own right, and the first movers are setting the rules everyone else will trade under.
