Countries at the United Nations shipping agency have struck a deal on a global fuel emissions standard for the maritime sector, which will impose an emissions fee on ships that breach it and reward vessels burning cleaner fuels.

The United States pulled out of the climate talks at the International Maritime Organization (IMO) in London this week, urging other countries to do the same and threatening to impose “reciprocal measures” against any fees charged to US ships.

Despite that, other nations have approved the CO2-cutting measures to help meet the IMO’s target to cut net emissions from international shipping by 20 percent by 2030 and eliminate them by 2050.

A majority of countries at the IMO voted on Friday to approve a scheme that from 2028 will charge ships a penalty of $380 per metric tonne on every extra tonne of CO2-equivalent they emit above a fixed emissions threshold, plus a penalty of $100 a tonne on emissions above a stricter emissions limit.

The deal is expected to generate up to $40bn in fees from 2030, some of which will go towards making expensive zero-emission fuels more affordable.

The talks have exposed deep rifts between governments over how fast to push the maritime sector to cut its environmental effect.

A proposal for a stronger carbon levy on all shipping emissions, backed by climate-vulnerable Pacific countries – which abstained in Friday’s vote – plus the European Union and the UK, was dropped after opposition from several countries, including China, Brazil and Saudi Arabia, delegates told the Reuters news agency.

Vanuatu’s climate minister, Ralph Regenvanu, said countries had “failed to support a set of measures that would have gotten the shipping industry onto a 1.5°C pathway”.

Industry group the International Chamber of Shipping welcomed the deal, which it said would require a huge scale-up of such fuels.

“We are pleased that governments have understood the need to catalyse and support investment in zero emission fuels,” ICS said in a statement.

In 2030, the main emissions limit will require ships to cut the emissions intensity of their fuel by 8 percent compared with a 2008 baseline, while the stricter standard will demand a 21 percent reduction.

By 2035, the main standard will cut fuel emissions by 30 percent, versus 43 percent for the stricter standard.

Ships that reduce emissions to below the stricter limit will be rewarded with credits that they can sell to non-compliant vessels.

“This is a groundbreaking moment for the shipping industry, which should signal a turning of the tide on greenhouse gases from global shipping,” Mark Lutes, senior adviser at the NGO World Wildlife Fund for Nature, said in a statement.

“However, key aspects of this agreement fall short of what is needed and risk blowing the transition off course,” he added.

The carbon pricing measure must now be formally adopted at an IMO assembly in October.