A major maritime industry association on Monday backed plans for a global surcharge on carbon emissions from shipping to help fund the sector's shift toward climate-friendly fuels.

The International Chamber of Shipping said it's proposing to the United Nations that all vessels trading globally above a certain size should pay a set amount per metric ton of carbon dioxide they emit.

The group, representing commercial shipowners and operators covering over 80% of the world merchant fleet, didn't specify what carbon price it would support.

The shipping industry is estimated to account for nearly 3% of the greenhouse gas emissions that are driving global warming and projected to rise significantly in the coming decades.

Environmental campaigners welcomed the ICS submission to the International Maritime Organization, but cautioned that the extent of its ambition remains unclear.

“We will know they are serious about real progress when they embrace a level of ambition consistent with what climate vulnerable island nations have already proposed,” said Aoife O’Leary, director of global transportation at the Environmental Defense Fund.

The Marshall Islands and the Solomon Islands, two nations with large shipping fleets that are severely threatened by climate change, have already proposed a carbon levy starting at $100 per ton.

The ICS said it opposed piecemeal regional measures, such as those proposed by the European Union, and called for the money generated from the levy to go into a climate fund that would subsidize clean alternatives such as hydrogen until they come competitive with conventional fuels.