The shipping sector will have to monitor its carbon emissions for the first time under a new law agreed by the EU.
International shipping accounts for roughly 3 per cent of the world's emissions of carbon dioxide, but this could increase to 18 per cent by 2050 if regulation is not in place, according to the International Maritime Organisation (IMO).
The rules introduce a mechanism for monitoring, reporting and checking shipping emissions, but ship-owners will only have to monitor emissions from 1 January 2018, and only from ships of more than 5,000 gross tons. Naval and fisheries vessels will be exempt.
Environmental campaigners say the new EU law is weak because it only measures emissions rather than imposing limits, although they still welcomed it as progress towards tougher steps.
The law stops short of including shipping in the EU's Emissions Trading System (ETS), the bloc's flagship tool for cutting pollution, but EU officials said it was a step in that direction.
Gian Luca Galletti, environment minister for Italy, which is current holder of the EU presidency, said the agreement had "a great political value as well as technical".
Shippers, such as Denmark's AP Moller-Maersk, the group behind the world's biggest container shipping operator, said the law was a pragmatic solution.
The new rules are a follow-up to an October EU agreement on new targets to tackle climate change and a precursor to UN efforts to agree a global deal in Paris next year, but if an international deal is reached to reduce shipping emissions the European Commission will have to review the EU law.
Speaking on condition of anonymity, diplomats said Greece, Cyprus, Malta and Poland had voted against the law, but that had not been enough to block it.
The measure will now be subject to detailed scrutiny before the European Parliament votes on the final agreed text, probably in spring 2015.