With a capacity of 8,000 passengers spread across 20 decks, Royal Caribbean International’s Icon of the Seas – World’s largest cruise ship sets sail from Miami, capitalizing on the growing popularity of cruises.

Environmental groups are concerned that methane leaks from the world’s largest cruise ship’s liquefied natural gas engine, as well as those from other enormous cruise ships, may affect the ecology when the ship departs on Saturday.

Royal Caribbean International’s Icon of the Seas, which can accommodate 8,000 guests over 20 decks, sets sail from Miami, capitalizing on the growing trend of cruise tourism.

Although LNG burns more cleanly than conventional marine fuel and carries a higher risk of methane emissions, the ship is designed to run on LNG. Because of its short-term negative impacts, environmental groups claim that methane leakage from ship engines poses an intolerable risk to the climate.

“It’s a step in the wrong direction,” declared Bryan Comer, the head of the Marine Programme at the environmental policy think tank, International Council on Clean Transportation (ICCT).

“We would estimate that using LNG as a marine fuel emits over 120% more life-cycle greenhouse gas emissions than marine gas oil,” he stated.

Methane has warming effects that are 80 times worse over 20 years than those of carbon dioxide, therefore reducing emissions is essential to slowing the rise in global temperatures.

Industry experts claim that low-pressure, dual-fuel engines found on cruise ships such as Icon of the Seas cause “methane slip,” or the release of methane into the atmosphere during combustion. Although they are too tall to fit aboard a cruise ship, two more engines that are used on bulk carriers or container ships produce less methane.

According to Royal Caribbean, the new ship is 24% more carbon-efficient than what the International Maritime Organisation (IMO), the worldwide regulator of shipping, requires.

The majority of the world’s marine fleet runs on very low sulphur fuel oil (VLSFO), which produces more carbon emissions than LNG, according to Steve Esau, chief operating officer of Sea-LNG, an industry advocacy group.

It is “important to make sure that all the natural gas is converted to energy,” according to Juha Kytola, director of R&D and Engineering at Wartsila, the company that created the engines aboard cruise ships. Cruise engines use natural gas to generate electricity in a cylinder.

He said that Wartsila’s natural gas engine technology releases 90% less methane than it did twenty to thirty years ago. What is not converted can escape during the combustion process and into the atmosphere, he warned.

According to a study conducted in 2024 and supported by the ICCT and other partners, the average methane slip in cruise ship engines is projected to be 6.4%. Methane slip is assumed by the IMO to be 3.5%.

“Methane is coming under more scrutiny,” stated Anna Barford, a nonprofit organization’s Canada shipping campaigner, pointing out that the IMO stated last summer that addressing methane emissions is part of its efforts to reduce greenhouse gas emissions.

Sixty-three percent of the 54 ships scheduled for delivery between January 2024 and December 2028 are anticipated to run on LNG, as reported by the Cruise Line International Association. Approximately six percent of the 300 cruise ships in operation today run on LNG.

Modern cruise ships are being built to run on LNG, conventional marine petrol oil or bio-LNG, which is an alternative that makes up very little of the fuel used in the United States.

According to Nick Rose, vice president of environmental, social, and governance at Royal Caribbean, the company will switch up its fuel mix as the market changes.

Lionel Messi, the captain of Argentina who won the World Cup and is currently a player for Inter Miami, participated in the ship’s naming ceremony on Thursday.

He had been seen setting a football on a specially designed stand, which set off the custom of breaking a champagne bottle against the ship’s bow in a “good luck” gesture.

Quick Facts about the Icon of the Seas

• With a length of about 365 metres (1,198 feet) and a weight of 250,800 tonnes, the Icon of the Seas is the biggest cruise ship in the world. That is around five times the size of the Titanic.
• The ship itself was built and acquired for a substantial sum of €1.65 billion ($1.79 billion; £1.41 billion) by Royal Caribbean International.
• The cost of a ticket for each person on the Royal Caribbean website is between $1,723 and $2,639. Around Christmas, a high-season cruise will cost $5,124 per person.
• Saint Kitts and Nevis and Charlotte Amalie in the US Virgin Islands will be the stops on its inaugural voyage.
• The ship, registered in the Bahamas, features six water slides and seven swimming pools. It was built at a shipyard in Turku, Finland.
• It was constructed for $2 billion (£1.6 billion) and has over 40 eateries, lounges, and bars.