The 19-deck Costa Toscana eases to the dock and disgorges thousands of day-trippers to the souvenir shops and eateries of this old city, a 10-hour invasion of tourists that sends most locals into retreat.
“I don’t go downtown. It’s a sea of people,” says Clara Galán, a tech marketing specialist in Barcelona.
But for those among the 5,000 passengers who choose to stay aboard the ship, lounging at one of the four swimming pools, 13 dining rooms, or the disco, the Costa Toscana – and most of the other four huge cruise ships in port – keep the lights on and the engines purring all day. Some burn heavy duty fuel notorious for producing toxic sulfur, soot, and black particles. Others, like the Costa Toscana burn natural gas that cuts the soot but multiplies their global warming damage with methane.
Why We Wrote This
Europeans have been pushing back on overtourism. For many the issue is more than just crowds, it’s also pollution from vessels that visitors ride in on. Is there a way for port cities to have needed cruise dollars and cleaner air?
As the popularity of cruise ship vacations soars, so do concerns about the pollution the giant vessels create at sea and – most noticeably – when they stop at coastal cities.
Adjusting to air pollution
Barcelona, with its architectural marvels and bustling restaurants, is a mandatory stop for many of the more than 200 cruise ships on the Mediterranean circuit, which is second only to the Caribbean in cruising popularity. But the belching pollution frequently helps give Barcelona the distinction of having the worst air quality of any port city in Europe.
“You can feel it. You can see it,” says Xavier Laballós, who runs a school specializing in artificial intelligence in Barcelona. “When you drive past the cruise ships and see what is coming from their chimneys, you say, ‘We should not be doing this.’”
The European Federation for Transport and Environment said in a 2023 report that cruise liners run by Carnival Corp. alone emitted 43% more sulfur oxides than all of Europe’s cars. Barcelona topped the list of most polluted cities in 2022, the nonprofit group reported, saying cruise ships there emitted nearly three times more sulfur oxides than all the cars in the city.
One local activist group, Stop Cruise Ships, says its own air measurements last fall at the cruise ship docks in Barcelona showed nitrogen oxide pollution levels five times higher than limits recommended by the World Health Organization. Sulfur and nitrogen oxides contribute to acid rain and acidification of the ocean, and can cause health issues.
“I moved here from Amsterdam,” says American Lizzie LaCour, who has lived in Barcelona for two years. “The air pollution was a hard adjustment. I can feel it here.”
Searching for sustainable solutions
The Cruise Lines International Association (CLIA), which includes 310 vessels plying the world’s oceans, says in a 2025 report that its members are moving toward more efficient ways of operating and cleaner fuels. But some port cities say progress is too slow and they are moving to impose restrictions of their own.
Venice, for example, banned large cruise ships in 2021 – though enforcement is erratic – and saw an immediate drop in air pollution. About a dozen destinations around the world have moved to impose taxes, bans, or limits on cruise ships, including Amsterdam; Santorini, Greece; Valencia, Spain; Dubrovnik, Croatia; Key West, Florida; Monterey, California; and Juneau, Alaska.
Barcelona decided in July to close two of its seven cruise ship terminals by 2030, and plans to bring electrical connections to all of its docks, allowing ships to shut off their engines and use power that may be more cleanly generated. Barcelona’s Mayor Jaume Collboni last September said 1.6 million annual cruise ship visitors was “not sustainable.” Barcelona residents have been pushing back on tourism in recent years. Activists made news in June by using water guns to squirt tourists to show they are unwelcome.
The cruise industry talks of the business it brings to port cities and says it is developing ships powered by sail, solar energy, or carbon-free fuels. But industry observers say those technologies still are far from operating at scale, especially for the large cruise ships.
Tourism is vital to Barcelona and many cruise ports. However, locals say the tourists who debark for only a few hours but generally sleep and eat aboard ships are a bad deal for the city.
“It’s a dilemma,” acknowledges Regina Rodríguez Sirvent, an author in Barcelona who conducts small-group cultural tours, as she sips coffee in a café. “The locals complain about the tourism, but we need the tourists. We need the right kind of tourists, who are respectful of the culture.”
Daniel Pardo Rivacoba, who is active in a variety of groups fighting for a more sustainable city, criticizes the municipality and the cruise lines.
“More greenwashing,” he says of the cruise industry’s boasts of more sustainable cruises. “We want the elimination of cruise ship traffic. I mean, it’s really a nonsense industry. It’s absolutely unnecessary, and it harms the environment, the city, the workers, and the economy of the place.”
The Barcelona municipal government, Barcelona Port Authority, Carnival, and CLIA all declined repeated requests to discuss these criticisms.
Sönke Diesener, at the Nature and Biodiversity Conservation Union, one of Europe’s largest nonprofit environmental organizations, works to expand 2015 rules first adopted for California and Europe’s Baltic and North Seas to reduce sulfur content in ship engine fuel.
The regulations prompted some cruise ships to start using a lighter-grade diesel fuel, he says. Others continue to use the toxic – and cheap – heavy fuel oil, and installed scrubbers to reduce the sulfur from their exhaust. But the scrubbers are constantly washed by sea water.
“They just take [sulfur] from the air and release it to the sea, not cleaning anything,” he says from Berlin. “They clean the air, so humans don’t breathe it, but it’s toxic for a lot of water organisms.”
Other ships moved to liquified natural gas, and advertise cruises on those vessels as environmentally friendly. But the extraction and burning of natural gas produces methane, an extremely potent greenhouse gas.
The environmental concerns have not hampered the popularity of cruise tourism. Nearly 30 million passengers took cruises on CLIA member ships in 2019, according to the group’s 2025 report. After a near-standstill of vessels during the COVID-19 pandemic, 35 million passengers cruised last year and the industry predicts that number will grow to 42 million in 2028.
“I really understand the appeal of taking a cruise,” says Bryan Comer, the marine program director at the Washington office of the International Council on Clean Transportation, a nonprofit research group begun in Italy in 2001. “It’s an all-in-one experience. You stay on board, you can eat on board, you can be entertained on board, and then you sail to all these beautiful places. But the consequences are that all of the beautiful places that you’re visiting are being disproportionately harmed.”
A study by his group found the average cruise ship passenger is responsible for far more carbon dioxide emissions than a vacationer flying or driving and staying in hotels at the same destination.
Taxes and levies to help fund research
There are ways to improve the pollution problem, says Sam Hargreaves, at the nonprofit Transport & Environment in Brussels. Port cities can create renewable power supplies and require cruise ships to use them while in dock. “Plugging in at ports, instead of running on fossil fuels when they’re idling … that is something you could change quite easily.” He says researchers ought to accelerate work on using carbon-free fuels. And governments might consider a tax on tourists to fund that work.
“You could put a levy on cruise ships, which directly goes into green technology,” he says. “Cruising is a luxury product. It’s not a necessity.”
