Countries have agreed a "ground-breaking" deal to cut greenhouse gas emissions from shipping by at least 50% by 2050 in a bid to tackle climate change.
The agreement by more than 170 countries, which comes at the end of two weeks of talks at the UN's International Maritime Organisation (IMO) in London, is the first time the shipping industry has signed up to climate targets.
It pledges to ensure shipping emissions peak as soon as possible and be reduced by at least 50% by 2050 on 2008 levels, while pursuing efforts towards phasing them out in line with global goals to limit temperature rises.
The move means all new ocean-going vessels are likely to be using alternative fuels - such as sustainable biofuels, batteries or hydrogen - from the 2030s, experts said.
But it is less ambitious than was being sought by some Pacific island states led by the Marshall Islands, which are at high risk of rising seas but also a major flag state, and the European Union, which wanted cuts of 70% to 100% by 2050.
The international shipping industry, which carries four fifths of the world's trade, accounts for between 2% and 3% of global greenhouse gas emissions.
But with countries taking action to cut their national emissions under the global Paris Agreement on climate change, shipping's share could rise to almost a fifth of the total by mid century without action, it has been warned.
Under the Paris deal, which does not directly include shipping and aviation, countries committed to keeping temperature rises to "well below" 2C above pre-industrial levels and to pursue efforts to curb them at 1.5C.
This requires global greenhouse gas emissions to fall to net zero by the second half of the century.
The International Chamber for Shipping's secretary general Peter Hinchliffe said of the IMO deal: "This is a ground breaking agreement - a Paris Agreement for shipping - that sets a very high level of ambition for the future reduction of carbon dioxide emissions.
"We are confident this will give the shipping industry the clear signal it needs to get on with the job of developing zero carbon dioxide fuels, so that the entire sector will be in a position to decarbonise completely, consistent with the 1.5C climate change goal."