Commentary: Ship pollution visible from space

   Forget the Great Wall of China and mighty Amazon River, NASA has posted an image on its Global Climate Change Website that shows global shipping routes can be seen from space because of the nitrogen oxides (NOx) emitted by ships traveling along them.
   “Just how much shipping contributes to overall NOx emissions remains an open question for scientists. Research suggests that shipping accounts for 15 to 30 percent of global NOx emissions; scientists are using satellite observations to reduce the uncertainty in such estimates,” the U.S. space agency said in a statement February.
   The shipping industry is working to reduce NOx emissions. The International Maritime Organization noted marine diesel engines installed on a ship built on or after Jan. 1, 2011 must comply with the Tier II standard set by regulation 13 of MARPOL Annex VI. Marine diesel engines installed on ships constructed on or after Jan. 1, 2016 must comply with the more stringent Tier III NOx standard, when operated in a designated NOx emission control area. (Chris Dupin)