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This is actually a good point. What about all the pollution that is NOT happening because those thousands of people are on a cruise for the week? Probably takin

This is actually a good point. What about all the pollution that is NOT happening because those thousands of people are on a cruise for the week? Probably taking flights somewhere, yes? And driving cars. All externalities should be compared against the alternative.

runarberg 3y ago
This is HN we like to look for and present the data here: > the world’s largest and most efficient cruise ships emit about 250 gCO2/pax-km.[1] > The average passenger vehicle emits about 400 grams of CO2 per mile [250 gCO2/km].[2] So a cruise ship running almost continuously emits about the same per passenger as the average car. The average car however does not run continuously and often has more than one person in it. So for the cruise ships to actually prevent emissions, the people that are in the cruise ships need to have otherwise been continuously driving alone in their cars at around 40 km/hour (25 mph) 24 hours a day for the 1-6 weeks they spend on the cruise. I highly doubt their daily lives pollute this much—even given their average wealth. 1: https://theicct.org/marine-cruising-flying-may22/ https://theicct.org/marine-cruising-flying-may22/ 2: https://www.epa.gov/greenvehicles/greenhouse-gas-emissions-typical-passenger-vehicle https://www.epa.gov/greenvehicles/greenhouse-gas-emissions-t...
- jaybrendansmith 3y ago
  Thank you. But what if you factor in a flight? This assumes you need to travel to your vacation destination of course. That's additional miles travelled in an aircraft at 31 gCO2/km, would be 1000s of km that you don't need to factor in for a cruise.
  - runarberg 3y ago
    I didn’t, but quite many people actually fly to and from the the cruise’s start harbor and destination. Medium haul passenger flights tend to by around 180-200 g CO2 per passenger km, so (surprising to many) less then a single occupant car. If your cruise passenger would instead fly to every single of the cruise’s stop, they can actually expect to emit less. However this kind of detailed analysis is out of scope for me personally. I don’t have the means to do excessive research factoring in various alternatives (and if I did I—as a non-expert—I would risk overfitting). For example a tourist arriving on an airplane is likely to stay in a hotel connected to the electricity grid, which is more likely to be fare more efficient and less carbon intensive than a cruise ship generating the onboard power with heavy fuel oil. I can, on the other hand, do a rudimentary ‘sniff test’ and locate easy to find data for what is going to be the biggest—perhaps even the overwhelming—factor, the emissions of the transport it self. And as such the claim that: “[we should consider] all the pollution that NOT happening because those thousands of people are on a cruise for the week” miserably fails. Looking into the emissions of an average cruise ship tells us the story that—to the contrary—we need NOT consider this.
    - jaybrendansmith 3y ago
      Ok fair enough. If we stipulate that, then we just need to regulate these emissions because they are getting a free ride on externalities. We just need to say 'if you wish to dock at our port, you must have a boat that emits less than x'. The market will then adjust by building ships that are cleaner. Cost of a cruise will go up by a few bucks, problem solved.
osigurdson 3y ago
These are great points but I do think this article is primarily about local NOx, not global CO2.

runarberg 3y ago

This is HN we like to look for and present the data here: > the world’s largest and most efficient cruise ships emit about 250 gCO2/pax-km.[1] > The average passenger vehicle emits about 400 grams of CO2 per mile [250 gCO2/km].[2] So a cruise ship running almost continuously emits about the same per passenger as the average car. The average car however does not run continuously and often has more than one person in it. So for the cruise ships to actually prevent emissions, the people that are in the cruise ships need to have otherwise been continuously driving alone in their cars at around 40 km/hour (25 mph) 24 hours a day for the 1-6 weeks they spend on the cruise. I highly doubt their daily lives pollute this much—even given their average wealth. 1: https://theicct.org/marine-cruising-flying-may22/ https://theicct.org/marine-cruising-flying-may22/ 2: https://www.epa.gov/greenvehicles/greenhouse-gas-emissions-typical-passenger-vehicle https://www.epa.gov/greenvehicles/greenhouse-gas-emissions-t...

jaybrendansmith 3y ago
Thank you. But what if you factor in a flight? This assumes you need to travel to your vacation destination of course. That's additional miles travelled in an aircraft at 31 gCO2/km, would be 1000s of km that you don't need to factor in for a cruise.
- runarberg 3y ago
  I didn’t, but quite many people actually fly to and from the the cruise’s start harbor and destination. Medium haul passenger flights tend to by around 180-200 g CO2 per passenger km, so (surprising to many) less then a single occupant car. If your cruise passenger would instead fly to every single of the cruise’s stop, they can actually expect to emit less. However this kind of detailed analysis is out of scope for me personally. I don’t have the means to do excessive research factoring in various alternatives (and if I did I—as a non-expert—I would risk overfitting). For example a tourist arriving on an airplane is likely to stay in a hotel connected to the electricity grid, which is more likely to be fare more efficient and less carbon intensive than a cruise ship generating the onboard power with heavy fuel oil. I can, on the other hand, do a rudimentary ‘sniff test’ and locate easy to find data for what is going to be the biggest—perhaps even the overwhelming—factor, the emissions of the transport it self. And as such the claim that: “[we should consider] all the pollution that NOT happening because those thousands of people are on a cruise for the week” miserably fails. Looking into the emissions of an average cruise ship tells us the story that—to the contrary—we need NOT consider this.
  - jaybrendansmith 3y ago
    Ok fair enough. If we stipulate that, then we just need to regulate these emissions because they are getting a free ride on externalities. We just need to say 'if you wish to dock at our port, you must have a boat that emits less than x'. The market will then adjust by building ships that are cleaner. Cost of a cruise will go up by a few bucks, problem solved.

osigurdson 3y ago

These are great points but I do think this article is primarily about local NOx, not global CO2.