Perhaps you missed this part: "109,000-horsepower engines that endlessly spin away 24 hours a day, 280 days a year." Most cars, in comparison, are idle for ov

Perhaps you missed this part: "109,000-horsepower engines that endlessly spin away 24 hours a day, 280 days a year." Most cars, in comparison, are idle for over 95% of their lifetime. My car for example sits in a driveway or parking lot approximately 23 hours a day. Brings another factor of 20 into play. Now 1 ship only needs to produce pollution equivalent to 2.5m cars. (Claim in the article still seems dubious considering that an average car has a 100 - 200 hp engine these days).