Maritime nations have agreed to keep working on a plan to introduce the world’s first global carbon fee on shipping emissions, but delayed a final decision and left room for alternative proposals.

The agreement came after a week-long meeting at the International Maritime Organization headquarters in London, where countries were expected to move closer to adopting new global rules, known as the “Net-zero Framework,” to cut pollution from the shipping sector.

Instead of finalising the plan, delegates decided on Friday to hold further discussions in the fall before a possible vote later in the year. The existing framework will remain the basis for negotiations.

Several countries proposed changes and alternative ideas during the meeting and insisted those options should continue to be considered. Meeting chairman Harry Conway of Liberia assured delegates that both existing and new proposals would be reviewed in upcoming sessions.

Some countries, including Australia, warned that reopening discussions could delay urgent action at a time when climate impacts are worsening and the shipping industry needs clear direction to invest in cleaner technologies.

IMO Secretary-General Arsenio Dominguez said progress had resumed but urged countries to rebuild trust and continue dialogue.

Climate advocates said the framework remains intact, with broad support from many nations, but cautioned against prolonged negotiations.

If adopted, the rules would introduce a pricing system that charges ships for greenhouse gas emissions above set limits, effectively creating the first global carbon tax for the sector. However, countries like the United States and Saudi Arabia have strongly opposed such a fee.

The framework was initially agreed upon last year, and its formal adoption had been expected in October. But the process was delayed after opposition led by the United States, backed by Saudi Arabia and others.

Shipping currently accounts for about 3 percent of global emissions, largely due to the use of heavy fuel oil. As global trade has expanded, emissions from the sector have also increased.

The proposed framework aims to gradually reduce emissions from marine fuels and create a fund from collected fees to support cleaner technologies, reward low-emission ships and help developing countries transition to greener practices.

Experts say such measures are crucial as the industry moves toward the IMO’s goal of reaching net-zero emissions by around 2050.

With large ships typically lasting about 25 years, industry groups say investments in cleaner fuels and technologies must begin soon to meet long-term climate targets.