Nations from 175 countries have gathered in London this week at the International Maritime Organisation (IMO) to hammer out the final details of a deal, more than a decade in the making, that could finally deliver a plan to decarbonise shipping over the next 25 years.

If the most ambitious proposals are realised, the agreement would also require all ships to pay a small charge based on the greenhouse gases they emit, with the proceeds going to fund climate action in poor countries. This levy is seen as a crucial source of funding for poor countries, which are seeing increasing economic devastation from extreme weather.

But powerful economies, including China, Brazil and Saudi Arabia, oppose the levy, while others, including the EU, may agree to drastically water it down.