Many cruise companies are touting their green credentials. But can cruise ships ever be sustainable?
In January, the world’s largest cruise ship set sail on its seven-day maiden voyage from the Port of Miami. The vessel, named Icon of the Seas, cost Royal Caribbean $2bn (£1.6bn) to build, has 18 decks, seven swimming pools and more than 40 restaurants, bars and lounges. It is 365m (1,195ft) long – 35m (115ft) longer than the Eiffel Tower and about five times as large as the Titanic.
The ship is powered by liquified natural gas (LNG) which Royal Caribbean has described as the “cleanest-burning marine fuel available”. But environmental campaigners say LNG harms the climate because it leaks polluting methane into the atmosphere, which is about 80 times more potent than carbon dioxide (CO2) over a 20-year time span.
The industry’s impact on the natural world is only set to grow as cruising booms. Ticket sales for cruise ships in 2024 have reached an all-time high. By the end of the year, 360 cruise ships are projected to have carried a total of 30 million passengers, a 9.2% increase compared to 2019, before Covid-19 hit. “The problem is that the number of cruise ships keeps growing and the size of those cruise ships keeps growing as well,” says Constance Dijkstra, shipping campaigner at the non-profit Transport & Environment. This will lead to more air and ocean pollution, she adds.
Many cruise companies have started touting their green credentials. But Dijkstra and other campaigners say that few are reducing their environmental footprint fast enough.
Cruise contamination
A large cruise ship can use up to 80,645 gallons (304,593 litres) of marine fuel per day, according to analysis by the University of Colorado Boulder. Marine fuels are variants of emissions-producing fossil fuels and therefore have a high carbon footprint.
Cruises are also a particularly carbon-intensive way to travel compared with many other types of holiday. The average CO2 emissions of a passenger on a cruise around Seattle are eight times higher than those of a tourist spending their holiday on land in Seattle, an analysis by the non-profit Friends of the Earth concluded.
And it’s not just atmosphere-warming CO2 that’s the problem. The 218 cruise ships operating in Europe in 2022 emitted more sulphur oxides (SOx) than one billion cars, or 4.4 times more than all the continent’s cars, according to additional analysis by the non-profit Transport & Environment. SOx can harm trees by decreasing growth and contribute to acid rain which can damage sensitive ecosystems. Exposure to the pollutant can also harm the human respiratory system and cause breathing problems. “We continue to caution people: ‘If you’re concerned about the environment, perhaps think about another kind of vacation,'” says Marcie Keever, director of the oceans and vessels programme at Friends of the Earth. But is cruising worse than flying?
Even the most efficient cruise ships emit more CO2 per passenger kilometre than a passenger jet, according to analysis by the International Council on Clean Transportation (ICCT), a US-based non-profit.
Waste is another major problem. More than 31bn litres (8.5bn gallons) of toxic waste were discharged off the west coast of Canada by cruise ships travelling to and from Alaska in 2019. Plus, noise pollution from ships harms marine life. A 2012 study found that mid-range noise from ships’ sonar overlaps with blue whales’ calls to each other, forcing them to repeat their vocalisations and disrupting their communication. (Read more about the surprisingly simple solutions to protect ocean life from man-made noise.)
Cleaning up cruising
Port cities are starting to crack down on cruise ships amid mounting health and environmental concerns. In 2021, Venice banned cruise ships from entering its historic centre, restricting them to the industrial port in response to a request from UN cultural body Unesco due to cruise pollution damaging historic buildings. Amsterdam and Barcelona have also banned cruise ships from their centres, in a bid to curb pollution and reduce overtourism.
“This is an industry that’s flown under the radar when it comes to regulation,” says Keever. “We’re now seeing communities stand up to cruise ships and say ‘the environmental pollution and the amount of passengers you’re bringing here is too much.'”
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Norwegian cruise company Hurtigruten is focusing on a different technology to power its ships: batteries.
The cruise line company Hurtigruten aims to launch a zero-emissions cruise ship by 2030, which will be powered by 60MW batteries and huge, retractable solar sails, as part of its “sea zero” initiative (Read more: Will shipping return to its ancient roots?).
“We are using advanced battery and solar technology alongside old-fashioned tech: sails,” says Hedda Felin, the company’s chief executive. “We have sun 24 hours a day in the summer in Norway and it’s very windy on the coast, so the ship is really tailored for the Norwegian coastline.”
Four of Hurtigruten’s fleet of nine cruise ships already have hybrid engines, which can run on both diesel and batteries.
“Hurtigruten are one of the leaders in the industry when it comes to adopting cleaner technologies, including [greener] fuels and advanced sewage treatment systems,” says Keever. “And this is important because they go to places like the Arctic.”
But there are limits to the distances batteries can power. The technology works well for Hurtigruten coastal cruises as “we are never more than six hours away from a port”, says Felin. But it is not a practical solution for ocean cruise liners. “If we were crossing the Atlantic, batteries would definitely not be considered,” says Felin.
Cruise companies visiting climate vulnerable locations, such as the Arctic, and bringing thousands of tourists to remote communities have a responsibility to operate more sustainably, says Felin.
“The cruise industry needs to take more responsibility…We are lagging behind massively,” she says, adding that cruise companies have been slow to transition to cleaner alternatives.
But Felin says there is hope on the horizon; new technology and fuels will help power a more sustainable future for cruise ships. “There are several proven and safe choices for the future which mean we do not need to have fossil fuels on our cruise ships,” she says. “That is the hope for the entire cruise industry.”
The Royal Caribbean did not respond to the BBC’s request for comment.
