I focused on CO2 because it's often cited and one of the more comparable metrics, and I used those articles only as sources for my estimates. Between the date of the article and today, significant new regulation for maritime fuels came out.

But the kind of environmentalists I am talking about aren't suggesting to regulate cruise ship emissions, they demand banning cruise ships, because they're a visible symbol of loosely-defined luxury/"excess", and thus any impact is seen as unjustifiable.