There are few means of travel worse for the environment than a cruise ship. Most of the ones that traverse the Mediterranean or the Caribbean do so while belching out toxic diesel fumes; when they are docked, they clog the air of their host ports even as their passengers wander the cobbled streets.
Cruise ships are only a small part of the shipping industry – but they are growing in size and number all the time, and there are good reasons to think they should be a priority for measures that might challenge their environmental impact.
“The whole of the shipping sector is given enormous tax breaks around the world,” said Jon Hood. “Their fuel is untaxed and their emissions are largely unpriced. The same subsidies don’t exist for road or air transport, which are clearly not taxed highly enough anyway given the environmental damage they cause. But where much of UK shipping is carrying the UK’s trade around the world, cruising is a luxury for the better-off. It’s entirely voluntary, and it’s pretty much the only part of the shipping sector in that category.”
The size of the industry
In 1970, there were 21 cruise ships in the world, the Transport & Environment report says. Today, there are 515, ranging from the opulent 1931 sailing yacht Sea Cloud, which carries 124 passengers and crew, to the shiny new behemoth Icon of the Seas, which is longer than 15 blue whales and carries almost 10,000 passengers. JP Morgan estimates that the cruise industry will be worth almost 4% of the £1.9tn global holiday market by 2028.
While baby boomers with money to burn are still a large part of the industry’s success, after a disastrous pandemic period, future growth rests on millennial and younger holidaymakers, with Royal Caribbean International saying that half of its customers are in that cohort. The average net worth of those under 40 who travel on cruises is now about $259,000. All of that means that cruise operators are ordering new ships in large numbers, with 60 expected to be added by the end of 2026 at an average price of $760m and an average capacity of 2,346 holidaymakers.
Cruise operators, meanwhile, are buying up private islands to increase the exclusivity of their offer. One such destination, Carnival Cruise Line’s Celebration Key, anticipates it will accept close to four million visitors annually by 2028 and promises an enormous “walkthrough sandcastle”, an 11,000-square-foot infinity pool, and a “uniquely Bahamian experience” with no access to anyone who isn’t coming on one of their ships.
The size of the ships
The ships are growing just as quickly as the industry is. The largest vessels around today are twice as big as they were in 2000; if they continue to grow at the same rate, Transport & Environment says, they will be 1.5 times larger by 2050 than they are today, or eight times the size of the Titanic. “They’re taking advantage of technologies that allow these ships to be built bigger and bigger,” Hood said.
It is already pretty hard to compute just how massive these things are: the Icon of the Seas has 2,800 guest rooms, 20 decks, 40 restaurants, seven swimming pools and an indoor waterfall. One summary of its many layers: “human lasagne”.
The newest and largest ships carry a disproportionate number of the passengers, maximising the efficiency with which the industry can accommodate growing demand – with 18% of the global fleet accounting for more than 50% of capacity. Hence the “cruisezilla” epithet.
The environmental impact
European cruise ships alone emitted more sulphurous oxides than 1bn cars in 2022, creating huge pollution in the cities where they dock, with debatable economic benefits for locals. In some places, cruise ships can plug into on-shore power and turn off their engines, eliminating toxic exhaust fumes linked to cancer, asthma and heart disease.
But that is more expensive to the operators than burning diesel, or marine gas oil, and the infrastructure is patchy. In Southampton, for example, only around one in 10 cruise ships plugged into shore power since it was brought online in 2022. (Some 14 cruise ships were expected to dock there this bank holiday weekend alone.) When not plugged in, a single ship can emit as much diesel exhaust as 34,400 idling lorries to power operations while docked.
“Based on current prices in the UK, shore power is around twice the price of using marine gas oil for an average cruise ship,” Hood said. “This is something market forces will not address. In the UK, there is a lack of infrastructure in many ports, and varied grid strength – in Southampton, for example, the local grid is not strong enough to cover the demand.”
Meanwhile, cruise ship CO2 emissions in Europe rose by 17% between 2017 and 2022, reaching the equivalent of 50,000 flights between Paris and New York. Methane emissions rose more than 500% over the same period. Compared to flights more generally, cruises produce considerably more carbon emissions per passenger-kilometre: twice as much as the equivalent flights plus hotel stays for the same period.
All of that adds up to a hefty environmental cost. The primary reason is that it is impossible for the biggest cruise ships to carry the enormous batteries they would need to power their operations, and so burn fossil fuels instead – with a severe shortage of renewable hydrogen-based e-fuels to replace them. Some run on liquified natural gas (LNG) and call that a clean fuel because it produces less carbon dioxide than marine alternatives – but because it also produces methane throughout the supply chain and when some gas is not burned, the true climate impact is larger.
“The cruise industry are absolutely greenwashing when they call LNG a green measure,” Hood said. “We want to see these companies invest in genuinely cleaner fuels if they’re going to trumpet their green credentials as they do.”
The calls for reform
Transport & Environment has produced a list of essential reforms, from limiting cruise ship traffic in areas vulnerable to marine and air pollution to demanding full industry disclosure of emissions for each ship to make greenwashing harder. It also proposes a tax on cruise tickets to raise additional climate finance, a measure that it estimates could raise €1.6bn a year at €50 a ticket.
But their first demand is for stricter rules around decarbonisation: enforcing the greater use of genuine e-fuels, connections to shore-side electricity while docked, and new decarbonisation requirements – tighter than current EU law, which requires an 80% reduction in greenhouse gas emissions by 2050 compared with 2020 levels.
The EU is bringing in significant penalties for sailing on dirty fuel from next year, which should incentivise the industry to change. The UK has no such scheme in place. “The UK’s strategy on this was supposed to be published in 2022, and it never appeared,” Hood said. “That has to happen without delay.”
Other than the surely universal desire to closely scrutinise any economic model that involves the provision of indoor waterfalls on the high seas, there are good reasons that cruise ships should be out in front on all of this. “They run more predictable routes than other shipping, they know exactly where they’re going to be and when, which makes it a lot easier to start to make these changes,” Hood said. “But at the moment, they’re a luxury industry, dumping their pollution on society and being allowed to get away with it.”
