The International Maritime Organization’s upcoming carbon intensity scores are expected to deal cruise ships a ratings blow if they spend more time in port and less time on the move.

But Carnival Corp chief maritime officer William Burke explained how the industry giant could use newer vessels outfitted with fuel-saving microbubble technology, known as air lubrication, to tackle itineraries that are more challenging under the new rules.

The Carbon Intensity Indicator, or CII, gives vessels scores between A and E based on how much CO2 they emit per capacity per nautical mile travelled.