In 2022, Bryan Comer, director of the marine programme at the International Council on Clean Transportation, examined the carbon footprint of cruising compared to a hotel stay plus air travel – since cruises are effectively floating hotels.
His analysis found that a person taking a United States cruise for 1,200 miles (1,931 kilometres) on the most efficient cruise line would be responsible for roughly 1,100 pounds (500kg) of CO², compared with 518 pounds for a round-trip flight of the same distance and a stay in a four-star hotel.
In other words: taking a cruise generates “about double the amount of total greenhouse gas emissions” as flying, Comer says.
Adora Magic City, the first made-in-China cruise ship, to set sail from Shanghai
Adora Magic City, the first made-in-China cruise ship, to set sail from Shanghai
Not to mention “usually people fly to take a cruise”, says Stella Bartolini Cavicchi, marine policy adviser at OceanMind, a nonprofit that uses satellite and other technologies to understand humans’ impact on the sea.
Flying to a cruising port means you “end up with quite a carbon-intensive holiday”, she says.
A Royal Caribbean spokesman says the Icon is designed to operate 24 per cent more efficiently than the international standard for new ships, which per International Maritime Organisation (IMO) regulations must already be 30 per cent more energy-efficient than those built in 2014.
The company will also monitor the Icon “over the next six to 12 months to ensure that we’re getting what we were designing the ship to be”, the spokesman said.
In 2022, the most recent year for which data is available, Royal Caribbean’s direct emissions totalled 5.5 million tons of CO² equivalent, up from 5.3 million tons in 2019.
Just a few years ago, the cruise business seemed like it was in dire straits. When Covid-19 travel restrictions grounded ships for months on end, there was major concern in the industry that passenger interest would be slow to return. But as soon as restrictions were lifted, “people did not think twice”, Bartolini Cavicchi says.
“The Oceania world cruise sold out within one day in January 2021. People were just dying to get back out there.”
The Cruise Lines International Association (CLIA), which says its membership accounts for roughly 95 per cent of global cruise trips, predicts passenger volume will hit 36 million this year, up from almost 32 million in 2023 and 30 million in 2019.
Last year, the ClimateTrace coalition (of which OceanMind is a member) published an analysis that found cruise ship emissions are already 6 per cent higher than they were before the pandemic.
Cruise ships’ climate impact isn’t limited to emissions that trap heat in the atmosphere. The enormous vessels also spew a soot-like substance known as black carbon, which absorbs sunlight and traps heat on the ground.
You’ve got things like heating the pool and keeping the lights on. [You] have heating and air conditioning; you’ve got the casino
In the Arctic, which is seeing a growing number of cruises, black carbon can settle on snow and ice, speeding up the rate at which glaciers melt. Bartolini Cavicchi says that while cruise liners account for around 1 per cent of the global shipping fleet, they’re responsible for 6 per cent of black carbon emissions.
Cruise ships, by contrast, are energy hogs: paying holidaymakers expect more square footage and modern cruises offer a slew of amenities.
“You’ve got things like heating the pool and keeping the lights on,” Comer says. “[You] have heating and air conditioning; you’ve got the casino. There’s just a lot of equipment to keep running to keep everybody entertained and comfortable.”
At the same time, cruise companies are quick to cite sustainability goals. Royal Caribbean Cruises, MSC Cruises and Norwegian Cruise Line have all pledged to reach net zero emissions by 2050, while Carnival plans to achieve carbon neutrality by 2050.
To meet those goals, cruise operators are increasingly replacing oil-based fuels with less carbon-intensive alternatives, most commonly liquefied natural gas (LNG). The CLIA says that, of the 44 new vessels on order between now and 2028, more than half will be powered by natural gas. The Icon of the Seas runs on a 300-ton LNG fuel tank.
Antarctica in style on a luxury cruise with champagne and submersibles
Antarctica in style on a luxury cruise with champagne and submersibles
LNG-powered ships do emit 25 per cent less CO² than those running on conventional marine fuels, but one 2023 investigation by environmental activists found that cruise ships running on LNG often leak some directly into the atmosphere as methane, a greenhouse gas that in the short term is 80 times more potent than carbon dioxide.
For three out of four engine types, the investigation determined that LNG was worse for the climate in the short term than conventional fuels.
Comer says cruise ship operators could transition to more sustainable fuels. Replacing LNG with methanol – an alternative that has little to no emissions in its life cycle – would slash methane output.
The Royal Caribbean spokesman says that when the Icon was designed, eight years ago, LNG was the “next New-Age fuel for any ship” and the vessel’s engine was the most efficient option.
The company’s next ship – the Utopia of the Seas, slated for completion this spring – will have a different engine, designed to reduce the risk of methane leaks.
The Celebrity Xcel, which is part of Royal Caribbean’s Celebrity subsidiary and expected to begin operations in 2025, is being designed with an engine that can run on three kinds of fuel, including methanol.
The maritime industry overall is under pressure to cut emissions. Last year, the IMO began requiring companies with ships over a certain size to calculate an Energy Efficiency Ship Index and to begin collecting data related to an operational Carbon Intensity Indicator (CII), which factors in a ship’s emissions, the amount of cargo being transported and the distance travelled.
Starting this year, ships will receive an A to E sustainability rating based on their data; those with a D rating for three consecutive years, or an E for one year, will have to submit a plan for improvement, though it’s unclear what penalties there are for poor performance.
But the cruise industry is pushing for a metric that doesn’t factor in distance travelled, as cruise ships’ time in port means they’re likely to receive a worse CII rating. The vessels’ hotel-like infrastructure still requires significant energy use even when there are fewer people on board and no nautical miles being traversed.
“The metric is not set up for ships that do not move continuously,” says the Royal Caribbean spokesperson.
Recent research indicates this inconsistency could even incentivise cruise ships to adopt itineraries with more time on the move, which would increase their overall emissions. The authors suggested replacing distance travelled with percentage of time spent at sea.
