[1] https://www.eia.gov/totalenergy/data/monthly/pdf/sec3_23.pdf
https://www.ft.com/content/8bceef94-86cd-11e9-a028-86cea8523...
https://inews.co.uk/news/long-reads/cargo-container-shipping...
https://newatlas.com/shipping-pollution/11526/
https://www.afr.com/policy/economy/why-australia-is-not-maki...
My actual job is in the shipping route optimisation space. Sub-percentile improvements in fuel consumption for a single route result in hundreds of millions of dollars of fuel savings. Of a fuel that's both cheaper and far more polluting than diesel. It's pretty obvious that shipping fuel consumption and associated emissions eclipse personal transportation.
The inews source compounds this error, and is cited by the Medium blog.
The newatlas source confirms this: "The low grade bunker fuel used by the worlds 90,000 cargo ships contains up to 2,000 times the amount of sulfur compared to diesel fuel used in automobiles." The measurement is sulfur emissions and NOT CO2.
FT likewise discusses sulfur and not CO2: "Sulphur dioxide emissions from cars was 3.2m kt versus 62m kt from cruise ships, with Carnival accounting for half that, the study found."
The AFR link discusses seafood and not shipping emissions.