The head of the International Maritime Organization said Monday he’s continuing to “advocate and campaign” for global regulations to move the shipping industry away from fossil fuels, after the United States and Saudi Arabia blocked new rules last month.

The U.S. has blocked a global fee on shipping emissions as an international maritime meeting ended Friday without adopting new regulations.

Many of the world’s largest shipping nations have agreed to impose a minimum fee on every ton of greenhouse gases emitted by ships above certain thresholds in what's effectively the first global tax on greenhouse gas emissions.

Nations are trying to reach an agreement to charge commercial vessels a fee for their emissions in what would effectively be the world’s first global carbon tax.

Arsenio Dominguez, secretary general of the International Maritime Organization, says international shipping companies need to do more to decarbonize their fleets right now.