The chairman of the International Chamber of Shipping says the UN must enforce global regulations if the industry is to cut emissions, Reuters reports.

Some industry groups have called for a complete ban on high sulfur marine fuels, in favor of running the world’s merchant fleet on cleaner-burning distillate fuels.

But ICS chairman Spyros Polemis said running ships on cleaner fuels could end up producing more emissions because of energy-intensive refining.

The International Council on Clean Transportation recently issued a report finding that ocean-going vessels produce more sulfur dioxide emissions than all the world’s cars, trucks and buses combined.

In addition, a study from the International Maritime Organization predicts that emissions from the global fleet will increase 72 percent in the next 20 years as globalization leads to increased demand for bigger, faster ships.