Rich nations and large developing countries are “backsliding” on a long-awaited deal to cut carbon from shipping, according to several poorer nations among those gathered in London this week at the International Maritime Organisation (IMO). According to The Guardian, the agreement could also require all ships to pay a small charge based on the greenhouse gases they emit, with the proceeds going to fund climate action, seen as a crucial source of funding for poor countries, which are seeing increasing economic devastation from extreme weather.

Nations from 175 countries are attending the IMO meeting, which ends April 10, to hammer out the final details of a deal, more than a decade in the making, which could finally deliver a plan to decarbonize shipping over the next 25 years. But richer countries, including China, Brazil and Saudi Arabia, oppose the levy, while others, including the EU, may agree to drastically water it down.

Poor countries fear the negotiations are already falling apart, The Guardian reports. Ambassador Albon Ishoda from the Marshall Islands, speaking for an alliance of Pacific and Caribbean small island states, said rich nations and large developing countries were “backsliding” on previous promises.

Arsenio Dominguez, secretary-general of the IMO, said he was confident the meeting would produce the long-awaited settlement on decarbonizing shipping. “Just under two years ago, IMO member states were decisive in their commitments in the IMO 2023 greenhouse gas strategy to approve at [this year’s meeting] midterm measures to cut emissions from ships, including a global fuel standard and an emission pricing mechanism,” he said.