Yeah, technically those are indirectly greenhouse gases, but just to note, the article linked points out that "Maritime transport accounts for 3.5% to 4%". It'

Yeah, technically those are indirectly greenhouse gases, but just to note, the article linked points out that "Maritime transport accounts for 3.5% to 4%". It's double-digit percentages of some pollutants that are very bad for human health, but relatively minor in terms of climate change. EDIT: I take it back. NOx is significant. SOx not so much.