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Despite adverse political headwinds and a general global retraction from climate action and multilateral commitments, a sub-field of climate policy continues expanding: carbon pricing. According to the latest reports by the World Bank and ICAP, as of today almost 30% of global emissions are covered by carbon pricing – be it in the form of an emissions trading system (ETS), a carbon tax, or hybrid measures.
The revamped interest in carbon pricing by countries, including capitals outside the G20 circle, is mainly fuelled by the entry into force of the European and, soon, UK carbon border adjustment measures (CBAMs). At the same time, rules for Article 6 of the Paris Agreement, adopted at COP29 in Baku in 2024, are pushing further developments and (expected) growing demand for carbon credits, especially after the reopening of the EU’s climate policy toolbox to international credits as part of the political compromise that led to the adoption of the 2040 goal between 2025 and 2026.
However, missions from two sectors are proving more difficult to price, tax and, ultimately, reduce: aviation and maritime transport. Emissions from the aviation sector are even expected to grow in the next decade, while sustainable aviation fuels and other decarbonisation solutions are not yet reaching the scale necessary to consider possible large-scale alternatives.
The EU ETS strictly covers emissions from flights within and between countries in the European Economic Area (EEA), plus departing flights from the EEA to Switzerland and the United Kingdom. Similarly, since January 1, 2024, large cargo and passenger ships calling at European Economic Area (EEA) ports must monitor, report, and surrender allowances for their greenhouse gas emissions under the system: 100% of emissions from voyages between two EU/EEA ports, 50% of emissions are covered for voyages departing from or arriving at an EU/EEA port to/from a non-EU port. Aviation and maritime transport emissions are, on the other hand, not covered by the other large compliance system, the Chinese ETS.
The expansion of compliance carbon-pricing systems to these two sectors has proved particularly difficult, especially in some countries – it is no mystery, for instance, that this kind of policy is openly opposed by many US aviation operators. At the international level, propositive and ambitious countries have tried to create multilateral compliance instruments for both cases.
The Carbon Offsetting and Reduction Scheme for International Aviation, or CORSIA, has been adopted by ICAO in 2016, and will enter its compulsory phase in 2027 (under the scheme, aviation companies will have to offset all their excess emissions through Paris-authorised international credits beyond 85% of their 2019 emissions). IMO has launched an innovative carbon pricing scheme for international maritime shipping in 2025, the IMO Net-Zero Framework, then immediately blocked by the United States, Saudi Arabia and other like-minded countries. CORSIA itself is at high risk of failure, as there are high probabilities that some major jurisdictions (and their aviation companies) will ignore the start of the compliance phase in a few months from now, leaving the whole scheme only partially populated and, thus, ineffective. The European Commission will assess in July whether the scheme can prove robust enough or whether, instead, the EU ETS should be re-enlarged to international flights, not to leave the sector’s emissions uncovered for another decade.
In this very uncertain scenario for both aviation and maritime emissions, new initiatives captured the attention of international observers. Launched in 2023 and then endorsed by the African Union, the Africa Sovereign Carbon Initiative (ASCI) and the related Africa Sovereign Carbon Registry (ASCR) aim at creating an easily implementable national carbon-pricing system for emissions generated by international flights and maritime shipments, covering half of the emissions from the journey to the national airport or harbour, and half of the return trip, while leaving the remaining emissions to the discretion of the country of origin or final destination. The system levies $17 per tonne of CO2 until a total maximum cap per movement is decided upon with the implementing country, and revenues from the system are then reused in sustainable development projects in the country with direct involvement of the national government and, thus, bypassing any UN involvement or agency.
This “sovereign” experiment is operative in Djibouti, a crucial maritime commercial point, and has been endorsed by the government of Gabon (although implementation in the second country seems momentarily paused) and, very recently, Liberia. According to the Initiative’s website, several other countries are considering implementing the scheme, including Angola, Cameroon, Congo, Ghana, Ivory Coast, Kenya, and Tanzania – thus, not only least developed countries, which would be formally excluded from CORSIA compliance.
But how does the governance of this new system work? Who are the actors involved? From documents we have been granted access to, we observe a mixed private-public governance model, managed by a private foundation, the Africa Sovereign Carbon Registry Foundation, which sits on the governance board with representatives of the participating countries, the so-called “member states”.
The Foundation itself manages the Country Sovereign Carbon Registry, which certifies the contributions and oversees the reporting on carbon footprints and emissions. Independent, external auditors are then contracted for audits and compliance. and what about the revenues, who is actually managing the financial flows? It is once again the governance board, to which companies pay the levy; then the board reallocates the resources to a “national Carbon Agency” appointed by the government of the host country, supported by the Africa Carbon Solutions advisory firm. Several sustainable development projects have already been implemented in Djibouti based on the collected revenues.
This mixed governance scheme leaves some key questions open. Is it a new type of carbon tax? Would this system be capable of interacting with existing international mechanisms, such as Article 6 of the Paris Agreement? These two questions originate, as well, from the potential similarities we can observe or hint at with the European debate on CBAM discounts, CORSIA development, and the review of the EU ETS.
The Foundation, in some of the materials it circulated between 2025 and 2026, clarified that the ASCI is not a new carbon tax, as they do not consider a levy on emissions from international transport or shipment a proper tax; at the same time, the Foundation promotes ASCI as an Article 6.8-compatible “non-market” approach, as levies are directly collected without other market-based interactions. Both readings can be partially contested, and the nature of the experiment remains a unicum in the current carbon pricing ecosystem, also based on its de facto private-public governance.
“Article 6.8 is intentionally flexible and broad, designed to accommodate a wide range of approaches that support countries in implementing their NDCs, and the ASCI's combination of governmental coordination, capacity-building and revenue recycling into sustainable development fits well within that spirit,” says Simon Pfluger, Article 6 expert at the sustainable finance think tank Climate & Company.
“A crucial distinction must be drawn, however: the initiative itself may qualify as a non-market approach, but the carbon pricing instrument at its core might inherently qualify for Article 6.2, not 6.8; therefore, its accounting and transparency rules must be fully respected,” he adds. But, if a carbon price is unilaterally levied on operators by a single country, can that qualify as bilateral cooperation between parties of the Paris Agreement?
Technical details apart, the growing number of African countries (especially those that are not LDCs) willing to implement the scheme represents a strong signal to Brussels and Beijing, as any development towards it means, implicitly, that these governments do not believe in, or do not back, the upcoming entry into force of CORSIA’s global compulsory phase, or that any new carbon-pricing-related development will happen at the IMO level.
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