Cruise ships’ pollution

While the covid pandemic forced the cruise industry to an unexpected halt, rising vaccination rates and desire for freedom following successive lockdowns fuel a boom in reservations. So much as several industry leaders announced worldwide cruises lasting as much as nine months! However, with the COP26 closing last week and the urge to reduce CO2 emissions, it seems that worldwide cruises are a luxury for the elites with many hidden costs for the climate.

Cruise ships are floating cities, embarking thousands of passengers, crew members, fully-equipped rooms, restaurants, and leisure areas. The floating monsters are powered by heavy fuel oils, releasing large amounts of toxic particles. Cruise ships’ fume exhausts are essentially made of sulfur oxide (SOx) and nitrogen acids (NOx).  A 2019 study by the European Federation for Transport and the Environment reveals that the Carnival conglomerate, parent company to 7 European cruise line tour operators and 47 ships, emits 10x much sulfur oxides (SOx) as the whole European car fleet, that is 260 million vehicles.

Cruise ships pollute in different ways:

Air pollution from fume exhausts. Despite tightening regulations in Europe on air pollution following the “dieselgate” in 2019, analysis reveals that European cruise line operators are contributing disproportionately to coast-side pollution. Lack of regulations on exhaust fumes, combined with the capital-intensive nature of the cruise industry and low asset turnover, makes for slow change toward greener alternatives. Due to the high fuel consumption of the ships, motors are powered by heavy fuel oils that are less expensive than petrol or diesel, the same ones prohibited in the car industry due to health concerns. Fumes exhausts have also been identified as large contributors to ocean acidification and acidic rains. Additionally, coastal cities in which cruise ships stop, such as Marseille in France, have higher death rates attributed to air pollution, 10% of which comes from cruise ships alone.

Greywater and blackwater are wastewater from sinks, showers, laundry, sewage, wastewater from toilets, and medical facilities of cruise ships. They contain harmful bacteria, pathogens, diseases, viruses, intestinal parasites, and harmful nutrients. It not only causes bacterial and viral contamination of fish and shellfish, but it also impacts humans who consume them at the other end of the food pyramid. Furthermore, sewage waters are rich in nitrogen and phosphor, which both are nutrients feeding excessive algal growth threatening ecosystems equilibrium and killing fish.

Solid wastes generated on a ship include glass, paper, cardboard, and plastics. Solid waste entering the ocean becomes marine debris, posing a threat to marine life and coastal ecosystems. Cruise ships contribute to 24% of the worldwide marine solid waste, with one large cruise ship emitting as much as 8 tons of debris in one week.

Are there greener alternatives?

In 2019, the MS Roald Amundsen went afloat. This 450 passenger hybrid cruise ship is powered by large batteries used to power onboard facilities and reduce the ship’s motor emissions.

However, as for electric cars, large, fully electric cruise ships are not feasible yet due to battery limitations. While the Chinese government supports the development of Changjiang San Xia 1, fully electric vessels, performances and autonomy are yet to be tested. It seems however that the scale of fully electric cruise ships is much lower than current boats.

Furthermore, some techniques exist to mitigate the concentration of ultra-particles from fumes exhausts, such as putting filters on top of chimneys or changes in the fuel consumed by boats. However, these measures are short-term, and the industry will have to find new innovative alternatives to fossil fuel, as regulation is catching on. As a leisure industry, cruise operators could face extreme legislation constraints to go CO2-free in the foreseeable future. Furthermore, associated air and water pollution are clear negative externalities that the industry will have to reduce, as developed since 2019 in a paper from the European Federation for Transport and the Environment. 

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