Contractual information and agreements, such as nationally determined contributions (NDCs), investment agreements, or service agreements (e.g. research activities or emission audits), can be implemented on the self-enforcing network. In this regard, blockchain solutions have been proposed for the shipping sector in the EU, which is by law required to monitor, report and verify (MRV) CO2 emissions, fuel consumption, and other parameters from each ship using EU ports. By combining IoT and blockchain, this data can be tracked easily and immutably, increasing efficiency in the MRV process (EC, 2018b). The blockchain layer is the base protocol, which defines the overarching consensus and validation mechanism, as well as smart contract and wallet standards.