The Week in Alt Fuels: Ambition won’t be enough in International Shipping News 25/04/2026 The IMO’s Net-Zero Framework (NZF) faces threats not just from its opponents, but also from the procedural rules that govern its survival. Next week, the IMO’s Marine Environment Protection Committee (MEPC) will take up the MARPOL Annex VI amendments that would introduce the NZF as a new Chapter 5. Member states will debate implementation guidelines and when to reconvene the adjourned adoption vote, rather than adopting the framework itself. A draft version of the NZF was approved at MEPC 83 in April 2025 and is technically now at the adoption stage. Its formal adoption was expected at an extraordinary MEPC session in October 2025, but member states voted 57–49, with 21 abstentions, to adjourn the vote by one year. Calls to reopen and revise the draft text have raised questions of not only how many countries support it, but also which ones do. A watered-down framework could be adopted. A stronger framework could become stuck in procedural limbo. Or the NZF never enters into force. The procedural rules around votes, tonnage thresholds and implementation will determine which of those outcomes are most likely. Tacit vs explicit acceptance “Although the acceptance procedure forms part of the substantive draft amendment, there will likely be one vote to decide whether to proceed with tacit or explicit acceptance (unless the Chair has already determined consensus), and another vote to officially adopt the amendment,” said Sapphire Ross, policy officer at Opportunity Green. The IMO has historically relied on tacit acceptance. Only the 108 countries that have ratified MARPOL Annex VI are eligible to vote on the amendments, and a two-thirds majority of those present and voting must support the amendments for adoption. Once adopted, a 10-month acceptance period begins. The amendments are blocked if at least one-third of those 108 states, or states representing 50% or more of global tonnage, formally object. Without sufficient objections, the amendments take effect six months later. Explicit acceptance works differently. It requires at least two-thirds of member states, representing at least half of world gross tonnage, to formally ratify the amendments through their domestic processes before the framework can enter into force. This process could take years, or fail entirely. Procedural pandemonium The US and several petrostates are pushing for explicit acceptance of the framework. The choice of procedure matters because a small number of states control a disproportionate share of global merchant vessel tonnage. Liberia, Panama and the Marshall Islands account for 46.5% of the world’s deadweight tonnage, Opportunity Green’s Ross said, which gives them outsized influence over whether the framework will take effect regardless of the vote. Liberia and Panama backed the framework last year but have since joined proposals calling for major revisions. The Marshall Islands was previously aligned with Pacific island states in pushing for immediate adoption, but has not joined their similar submissions to MEPC 84. Under tacit acceptance, a coalition with enough tonnage can block entry into force even if most countries support the framework. Under explicit acceptance, the same group can stall implementation by moving slowly on domestic ratification, Ross explained. “Whilst this [explicit acceptance] may reduce the risk of a single blocking coalition, it introduces a di