The International Maritime Organization, which oversees the shipping industry, will begin enforcing rules this July that mandate cleaner fuel to cut air pollution and acid rain.
Regulations call for reducing the sulfur in shipping fuel from 4.5 to 0.5 percent by 2020. Scientists project that this switch will cut sulfur-pollution-related premature deaths from 87,000 worldwide per year to 46,000. But the sulfate aerosols spewing from supertanker smokestacks also produce planet-cooling clouds called ship tracks
Full story: New Clean-Fuel Rules For Ships Could Actually Hurt the Environment–Popular Science.