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The global shipping industry is enormous — thousands of ships carry billions of dollars of goods each year across nearly every ocean on the planet.

Those ships run mostly on a particularly dirty type of fuel known as heavy fuel oil, or bunker fuel. It’s thick and sooty, and when it burns, it emits sulfur and particulate matter that can cause respiratory illness. It also emits greenhouse gases, including carbon dioxide and methane, which trap heat in the atmosphere and cause global warming.

“If shipping was a country, it would be the sixth-largest polluter in the world,” says Nerijus Poskus of the shipping technology company Flexport. “About 3% of global emissions are released by ocean freight shipping.”

The industry is growing so steadily, he says, that it’s projected to produce more than 15% of global greenhouse gas emissions by midcentury if ships continue to burn the same fuel, which is a real possibility considering that most cargo ships are designed to last at least 30 years.

The Dawn Of Low-Carbon Shipping