Poor countries have accused the rich world of “backsliding” and betrayal of their climate commitments, as they desperately tried to keep alive a long-awaited deal to cut carbon from shipping. 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…