Global Shipping Emissions Talks Hit Turbulence as U.S. Walks Out Over Disputed Carbon Levy

The International Maritime Organization (IMO) is at a critical juncture this week in London, where negotiators aim to solidify binding regulations to slash greenhouse gas (GHG) emissions from global shipping. Yet, the path to progress is far from smooth. Deep divisions have already emerged, with the United States pulling out of the discussions and vehemently opposing key proposals.

The ongoing negotiations, convened under the IMO’s Marine Environment Protection Committee (MEPC 83), are centred around a bold, sweeping climate strategy that aims to steer the global shipping industry toward net-zero emissions by 2050.

Several proposals have already been laid out, including:

• Mandatory reductions in fuel-related emissions intensity.

• The introduction of a global carbon pricing mechanism.

• A Net-Zero Fund was created to support the transition to cleaner fuels and ensure equitable progress for developing nations.

If these proposals are ratified, they would be folded into the MARPOL Convention. This cornerstone international treaty governs air pollution from ships and regulates approximately 97% of the world’s merchant fleet.

A draft of the legal text is expected to be released by the end of the session on Friday, April 11. A formal vote is scheduled for October 2025.

However, while there has been limited progress on various environmental fronts—such as adopting a 2025 Action Plan to curb plastic litter from ships and new guidelines for transporting biofuel blends and handling hazardous materials—the atmosphere around the core issue of carbon pricing has become increasingly tense.

Introducing a global carbon levy on emissions from international shipping has emerged as one of the most contentious points in the negotiations. In a sharp move, the United States has formally withdrawn from discussions related to the carbon pricing proposal, setting the stage for a renewed diplomatic standoff.

A diplomatic note circulated to other governments outlined Washington’s stance: it would not support any international economic measures that directly target emissions or fuel choices. In particular, the US criticized the carbon levy proposal, asserting that such measures would unfairly “target” American ships. Furthermore, the message hinted at possible retaliatory actions should such proposals be adopted, urging other countries to reconsider their support for the carbon pricing initiative.

The statement read: “The US rejects any and all efforts to impose economic measures against its ships based on GHG emissions or fuel choice.

“Should such a blatantly unfair measure go forward, our government will consider reciprocal measures.”

As IMO decisions are grounded in consensus, the US’s exit from the negotiations could significantly derail any hopes of establishing a global carbon pricing system. The US’s efforts to rally opposition from other nations could spell the end of the line for such a mechanism—at least in the short term.

With the clock ticking down on this session, the proposed emissions framework's future remains uncertain. Supporters of the carbon levy view it as a critical tool—not just for tackling emissions but also for aligning the shipping industry with global climate targets. They argue that the levy is essential to generate much-needed investment in low—and zero-emission fuels and to create a level playing field within the fragmented global market.

As the negotiations inch forward, it’s clear that the IMO is facing a momentous crossroads. Whether a global carbon pricing scheme can overcome the challenges posed by major stakeholders like the US remains to be seen. However, with international climate goals at stake, this could be a defining moment for the future of maritime emissions regulations.

ING’s senior sector economist for transport and logistics Rico Luman said: “From an economic perspective, and to support a level playing field and the transition in global shipping, introducing a CO2 levy pricing is ultimately necessary.

“I fear that a compromise will emerge that is not ambitious enough. It is difficult anyway since this involves global and mandatory regulation, where a large number of member states must come to a consensus or support it.

“The momentum for measures has somewhat weakened, with the general attention more focused on geopolitical tensions and the trade war currently. At the same time, absolute GHG emissions have increased in global shipping in recent years.”