No, this misleading stat refers to sulfur and soot emissions, not CO2. It's true that ships at sea burn a cheap sulfurous fuel, "bunker fuel", because there's nobody to inhale it out there. But it's misleading because people think this stat refers to CO2, which it doesn't. Ground transport produces far more CO2 than ships, which by weight are the most efficient way of moving anything.
That's true, but the sulfur emissions from ships do not have this effect. They actually have a slight negative greenhouse effect, because they reflect light in the upper atmosphere.
