European aluminium importers can face two carbon-related cost elements within a single shipment under different EU rules. One is the embedded emissions liability under the Carbon Border Adjustment Mechanism (CBAM). The other is the carbon cost linked to maritime transport under the EU Emissions Trading System (EU ETS).
Maritime transport covered under the EU ETS since 2024
The EU ETS has covered maritime transport since 2024. For voyages within scope, shipping companies account for 50% of emissions from routes between an EU port and a non-EU port. For voyages between EU ports, 100% of emissions are covered, including emissions occurring within EU ports.
From 2026, the maritime ETS framework expands beyond carbon dioxide. It will also include methane and nitrous oxide in addition to CO2. This change affects how emissions are accounted for under the maritime component of the system.
Two mechanisms linked through EU allowance prices
For aluminium buyers, the maritime ETS creates a freight-related carbon exposure alongside the CBAM liability tied to embedded emissions in the metal. Although CBAM and maritime ETS impose separate legal obligations, their commercial effects can move together through the price of EU allowances (EUAs).
When EUA prices rise, an importer may see higher expected CBAM certificate costs. At the same time, shipping companies may seek to recover increased maritime compliance expenses through freight charges. This can create a correlated exposure across two parts of the import transaction.
Freight contract terms affect carbon cost pass-through
During periods of sharp EUA price increases, both border-related liability and shipping surcharges can move upwards. That movement can amplify changes in the landed price of aluminium. A company that hedges embedded emissions but excludes any carbon component of ocean freight may therefore misstate its overall sensitivity to the EU carbon market.
Importers are directed to review how maritime ETS costs are handled in freight agreements. Relevant arrangements include whether any carbon charge is fixed, variable, transparently passed through, or incorporated into a bunker adjustment mechanism. Companies also need to check whether freight indices or all-in shipping rates already include an ETS-related surcharge.
Quantifying combined exposure for aluminium import programmes
If an ETS-related surcharge is already reflected in freight pricing, internal landed-cost calculations may risk counting carbon costs twice. For large aluminium import programmes, a consolidated EUA sensitivity analysis can quantify combined exposure across CBAM and maritime costs. The approach described involves assessing how a €10/tCO2 increase in allowance price affects both estimated CBAM liability and expected carbon-related freight surcharge.
The CBAM and maritime ETS remain separate regulatory mechanisms. Their interaction means shipping-related carbon costs can become an increasingly relevant factor in aluminium procurement, freight contracting and treasury risk management.