I trust that statistic about as far as I can throw it. A better comparison would be: If there was a road from China to,say, San Francisco, what would be the pollutant load of the number of trucks required to carry the same load while running on Chinese diesel fuel. Ships are very efficient.
It would not be impossible and well within the state of the refinery art to remove most of the sulphur from bunker C. It would not be cheap and I wonder if it would mean a total rebuild of those diesels.
It would not be difficult, just very, very expensive, to make nuclear powered container ships. Would the North Koreans and Iranians be allowed to have them ?
I wonder what the pollutant load would be if we went back to proper coal fired steam ships.