The U.S. has abandoned international talks for a global carbon tax on emissions produced by oceangoing vessels, and has threatened to take reciprocal measures to offset any fees levied on U.S. ships.
In a letter to other member states of the International Maritime Organization (IMO), the U.S. unveiled its opposition to the tax, and any efforts to impose economic measures based on greenhouse gas (GHG) emissions or fuel choice.
The carbon tax is aimed at helping the IMO reach its net-zero GHG emissions objective by 2050, a goal the organization set in 2023.
“Should such a blatantly unfair measure go forward, our government will consider reciprocal measures so as to offset any fees charged to U.S. ships and compensate the American people for any other economic harm from any adopted GHG emissions measures,” the letter, seen by publications including Bloomberg and Politico, wrote. “The Trump administration will protect the American people and their economic interests.”
The IMO, the United Nations’ regulatory body over international shipping, is meeting in London this week to approve the proposed new global regulations
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The debate at the meeting will cover whether to tax shipping emissions through carbon credits trading plan or a universal levy, which would entail a flat-rate tax on emissions. A flat tax could charge as much as $150 per metric ton of GHG emissions per ship, with supporting actors saying the duty would generate billions of dollars a year to help developing countries cope with the impact of the climate crisis.
If the tax charged $100 per metric ton, it would raise an estimated $60 billion per year, according to IMO estimates.
Within the leaked document, the U.S. called on the other governments to reconsider their support of the measures, which “would impose substantial economic burdens on the sector and drive inflation globally.”
The U.S. previously showed support for the proposal under the Biden administration. The Trump administration had stayed out of the discourse to start 2025, but it now joins countries including China, Brazil, Saudi Arabia and South Africa in opposition of a tax.
On Jan. 31, those countries, and eight others, argued a levy could reduce exports from the developing world, raise food prices and increase inequalities.
“A levy would not deliver a just and equitable transition [to low-CO2 shipping] and its adoption may trigger negative, economy-wide impacts…a levy is a fundamentally divisive proposal,” they wrote.
According to the U.N., 3 percent of total carbon emissions worldwide have come from container shipping, with that figure increasing over the past decade due to the increased size of vessels and the amount of cargo traveling per trip.
The opposition from the U.S. and others has continued a common theme of disagreement among IMO member nations over the impacts of a shipping levy on global trade. The topic has only garnered more concern in the wake of President Donald Trump’s global 10-percent tariffs and an escalating trade war between the U.S. and China.
For the U.S., the move falls in line with many of President Trump’s positions that run averse to climate regulation. The president pulled the U.S. out of the Paris Climate Agreement for the second time upon returning to the Oval Office in January.
“The U.N. should halt all efforts to proliferate the deeply unfair agenda reflected in the Paris Agreement in other fora,” the leaked document said, indicating that “[a] plain reading of these measures is that they are foremost an effort to redistribute wealth under the guise of environmental protection.”
It is unclear if American opposition to a carbon tax will hamper wider decarbonization efforts across shipping, particularly if other countries follow the U.S.’s lead.
The IMO’s Marine Environment Protection Committee, the body that would approve the carbon emissions reduction measures, typically makes decisions by consensus. While a ballot is a possibility, the U.S.’s vote wouldn’t carry more weight than that of other nations, but it might be able to influence others into voting in a certain way.
Despite its dominance on the global economic stage, its fleet of commercial ships remains small compared to other countries.
Flag states—places where vessels are registered—are integral to implementing the IMO’s air pollution rules as they exercise regulatory control over issues such as working and living conditions for seafarers, boat safety and marine environment protection.