It's quite believable that passenger cars also account for something the neighborhood of 3% of total CO2 emissions. My point was not to say that shipping is completely irrelevant, it's to point out that it is not so grossly overpowering as your original comment suggested. The idea that a handful of ships match the CO2 emissions of all cars is completely divorced from reality.

If you want to find the exact number that cars account for, I'm sure you can find it. Just don't use whatever source you got that initial CO2 claim from.