Sulfur in petroleum fuels causes air pollution. Sulfur in cargo ship fuels also causes brightening of marine clouds. The streaks in the photo are where the sulfur particles in the ship exhaust have formed tracks of brightened clouds. The cloud brightening reduces global warming.

Is the harm of pollution caused by sulfur in the ship fuel worth the benefit of using high-sulfur fuels in shipping? In addition to brightening marine clouds which reduces global warming, high-sulfur fuels are less expensive than low sulfur fuels.

Should the shipping industry switch to low sulfur fuels or should it use high-sulfur fuels?