「綠色」遊輪對氣候有利嗎？

The Icon of the Seas, the world's largest cruise ship, recently embarked on its maiden voyage from the Port of Miami. This massive vessel, which cost Royal Caribbean $2 billion to build, boasts 18 decks, seven swimming pools, and over 40 restaurants, bars, and lounges. It stretches 365 meters in length and is powered by liquefied natural gas (LNG). While many cruise companies are promoting their green credentials, the question remains: can cruise ships ever truly be sustainable? Environmental campaigners argue that LNG, despite being marketed as a cleaner alternative, leaks methane into the atmosphere. Methane is significantly more harmful to the climate than carbon dioxide over a 20-year period. The cruise industry's environmental impact is expected to grow as the sector continues to expand. Ticket sales for cruises in 2024 are on the rise, and by the end of the year, 360 cruise ships are projected to have carried a substantial number of passengers, marking a 9. 2% increase compared to 2019, before the Covid-19 pandemic. Constance Dijkstra, a shipping campaigner at the non-profit Transport & Environment, highlights the issue of the increasing number and size of cruise ships, which contribute to more air and ocean pollution. A large cruise ship can consume up to 80,645 gallons of marine fuel per day. Marine fuels are variants of emissions-producing fossil fuels, making cruises a particularly carbon-intensive mode of travel. The average CO2 emissions of a passenger on a cruise around Seattle are notably high. In 2022, the 218 cruise ships operating in Europe emitted more sulfur oxides than one billion cars, contributing to acid rain and damaging sensitive ecosystems. Exposure to sulfur oxides can also harm human health. Marcie Keever, director of the oceans and vessels program at Friends of the Earth, advises people concerned about the environment to consider alternative vacation options. Waste management is another significant issue for the cruise industry. In 2019, a considerable amount of waste was dumped off the west coast of Canada by cruise ships traveling to and from Alaska. Additionally, noise pollution from ships disrupts marine life, with studies showing that mid-range noise forces marine animals to repeat their vocalizations, affecting their communication. In response to mounting health and environmental concerns, some port cities are taking action. Venice, for example, has restricted cruise ships to its industrial port to protect historic buildings from pollution. Other cities have also banned cruise ships from their centers to curb pollution and reduce overtourism. Cruise companies are implementing measures to improve their sustainability records, such as switching to more efficient engines and reducing plastic use. However, the industry's most significant challenge is transitioning away from polluting fossil fuels. Dijkstra emphasizes that achieving a green cruise requires a change in fuel, which is a complex task. While LNG is currently the best available fuel, it is not a perfect solution due to methane leaks. The cruise industry is exploring alternative fuels like methanol and ammonia, but these options are not yet viable at scale. The Cruise Lines International Association (CLIA) is calling on governments to set more ambitious production targets for sustainable fuels. Norwegian cruise company Hurtigruten is focusing on battery technology to power its ships. They aim to launch a zero-emissions cruise ship by 2030 as part of their 'sea zero' initiative. Four of Hurtigruten's ships already have hybrid engines that can run on both diesel and batteries. However, battery technology is not a practical solution for long ocean voyages. The cruise industry must take more responsibility for its environmental impact. New technologies and fuels offer hope for a more sustainable future for cruise ships. The Royal Caribbean did not respond to the BBC's request for comment.