Here's a thing about MDO and MGO. https://maritimepage.com/what-are-mgo-and-mdo-fuels-marine-fuels-explained/
MGO is 0.1% sulphur content.
MDO is 2% sulphur content.
For comparison, car diesel sulphur content is like 0.001%.
Best source I can find for bunker fuel is 3.5%.
So, MDO/MGO are better than bunker fuel, I guess. Feels like a rebrand with minor improvements, so everyone can say "yeh, it's just diesel. Not bunker fuel".
But 2% MDO is still a 40% improvement over 3.5% bunker fuel.
Seems like there is a lot of changing and outdated information on this.
And it being related to international trading, laws and standards... There doesn't seem to be a reliable definitive source on it.
My takeaway is "yeh, it's not bunker fuel. It's diesel. But it's not diesel as we know it from driving cars, trucks, tractors and other plant"
But when people talk about ship pollution, they're usually talking about non-carbon pollution.
For example, ships often burn heavy fuel oil, which produces tons of sulfur dioxide, which causes acid rain, and NOX, which depletes the ozone and causes smog and asthma.
Cruise ships are bad for the environment, but there's honestly bigger fish to fry. Gas power plants are way, way worse for the planet.
From the comparisons I've made in the past, they're also relatively cheap compared to land based vacations. For some reason, it's cheaper to make your hotel float.
Then there's places where ships are more inherent to the experience, like transiting the Panama canal, or coastal regions of Alaska or Norway. Places that are too remote to get to by most other means.
But fuck Caribbean cruises. That's a boat taking you from one tourist outdoor shopping mall to another.