Cruise Ships: How Much Do They Pollute Our Air?

Cruise ships have been described as floating cities, and they are just as polluting, if not more so. A medium-sized cruise ship emits greenhouse gases equivalent to those of 12,000 cars, and it could dump over 1 billion gallons of untreated sewage into the ocean. Cruise ships emit large amounts of sulfur oxides (SOx), nitrogen oxides (NOx), carbon dioxide (CO2), phosphorus (P4), soot, heavy metals, and other particulates into the atmosphere. In 2017, Carnival's cruise ships alone caused ten times more sulfur oxide (SOx) air pollution than all of Europe's cars (over 260 million) combined. In 2022, Europe's 218 cruise ships emitted as much SOx as 1 billion cars. Cruise ships make up only 1% of the global fleet but account for 6% of black carbon emissions.

Cruise ships emit large amounts of harmful sulphur oxide (SOx)

The impact of cruise ship emissions is particularly acute in port cities. For example, in 2019, Venice, Europe's most polluted cruise port, witnessed an 80% reduction in SOx emissions after banning large cruise ships. Similarly, in Marseille, France, 10% of the city's air pollution was directly attributed to the shipping industry, with cruise ships being a major contributor.

The high levels of SOx emissions from cruise ships are due to the type of fuel they use. A report by German watchdog Nabu in 2018 revealed that out of 77 cruise ships surveyed, all but one relied on highly polluting heavy fuel oil, described as the "dirtiest of all fuels." Cruise ships' fuel emits about 2,000 times more sulphur oxides than normal diesel fuel. As a result, cruise ships emit far more SOx than cars. For instance, in 2022, Europe's 218 cruise ships emitted as much SOx as one billion cars.

To address the issue of SOx emissions, some cruise lines have explored alternative energy sources. For instance, some ships have adopted liquefied natural gas (LNG) and shore power, allowing them to turn off their diesel engines while docked. While LNG reduces NOx and particulate emissions, it contains methane, a potent greenhouse gas that can contribute to global warming through leaks and incomplete combustion.

Despite these efforts, the growing number of cruise ships and their increasing time spent at ports continue to pose challenges in reducing overall SOx emissions. As the cruise industry expands and vessel sizes increase, the environmental and health impacts of SOx emissions from cruise ships will become more significant.

Cruise ships burn up to 4,900 litres of fuel per hour

Cruise ships have been a major contributor to environmental damage, particularly air pollution. Cruise ships burn up to 4,900 litres of fuel per hour, and in 2017, a single cruise line emitted ten times more sulfur oxide (SOx) than all of Europe's cars combined, totalling more than 260 million. This is because the ship fuel emits 2,000 times more sulfur oxide than normal diesel fuel.

The air pollutants emitted by cruise ships include nitrogen oxide (NOx), soot, carbon dioxide (CO2), phosphorus (P4), heavy metals, and other particulates. These emissions have severe health consequences, including premature death from lung cancer, throat cancer, cardiovascular diseases, and respiratory issues. In addition, cruise ships produce various waste streams, such as sewage, wastewater (grey water), hazardous wastes, solid waste, oily bilge water, and ballast water.

To address these environmental concerns, some cruise lines have transitioned from single-use plastic packaging to reusable containers and cutlery. Princess Cruises and Royal Caribbean Cruise Line, for instance, have adopted reusable items. Recycling programs have also been implemented, with the United States gaining over 18,000 pounds of recycled goods from these practices.

Furthermore, some cruise lines are turning to alternative energy sources to reduce air pollution, which also positively impacts marine environments. While docking, some cruise ships are required to use low-sulfur fuel or abatement technologies to reduce air pollution. However, critics argue that these measures are insufficient to protect the health of local residents.

The impact of cruise ships on the environment is significant, and their emissions contribute disproportionately to air pollution and climate change. The shift to cleaner energy sources and the adoption of more sustainable practices are crucial steps towards mitigating the environmental and health impacts of cruise ship operations.

Cruise ships produce various waste streams

While cruise ships are responsible for a significant amount of air pollution, they also produce various waste streams. These waste streams can be discharged into the marine environment, impacting the oceans and aquatic life. The waste streams generated by cruise ships include:

• Sewage: Waste from toilets and laundry facilities is often discharged into the ocean, contributing to water pollution.
• Greywater: Wastewater from sinks, showers, and galleys is known as greywater. It can contain soaps, detergents, and other contaminants that can harm marine life.
• Hazardous wastes: Cruise ships generate hazardous wastes and toxic substances during operations and maintenance. These wastes may include chemicals, oils, and other pollutants that require proper management and disposal.
• Solid waste: Cruise ships produce large amounts of solid waste, including garbage, food waste, and plastics. If not properly managed, this waste can end up in the ocean, posing risks to marine life and contributing to oxygen depletion.
• Oily bilge water: Bilge water collects in the lowest part of the ship's hull and often contains oil, grease, and other contaminants. Its improper discharge can have detrimental effects on water quality and marine ecosystems.
• Ballast water: Ballast water is used to stabilize cruise ships and can contain invasive species, chemicals, and pollutants that can disrupt local ecosystems when released into new environments.

The management and disposal of these waste streams are governed by international protocols, such as MARPOL, and domestic laws, such as the Clean Water Act and the Act to Prevent Pollution from Ships. However, there are concerns about the adequacy and enforcement of existing laws, with cases of illegal discharges by cruise ships in U.S. waters. To address these issues, some cruise lines have implemented initiatives to reduce waste production, promote recycling, and adopt alternative energy sources to mitigate air pollution.

Cruise ships' air pollution impacts port cities

The cruise industry is a highly lucrative sector, generating over $117 billion in 2017 and transporting more than 26 million customers. However, as the industry continues to grow and build new state-of-the-art ships, concerns about air pollution and emissions in port cities are also rising.

Cruise ships have been likened to "floating cities", producing a large volume of waste and emissions that impact the air quality of port cities. In Europe, cruise ships alone caused ten times more sulfur oxide (SOx) air pollution than all of Europe's cars combined in 2017. They also accounted for 15% of the nitrogen oxide (NOx) particles emitted by Europe's passenger vehicles and released high amounts of other pollutants such as carbon dioxide (CO2), phosphorus (P4), soot, heavy metals, and fine particles (PM2.5). These emissions have severe health implications, including respiratory and cardiovascular illnesses, lung cancer, throat cancer, and childhood asthma.

The impact of cruise ship emissions is particularly pronounced in port cities. In Southampton, UK, air pollution from docked cruise ships is comparable to the pollution levels of a town with 50,000 inhabitants. In the same city, school playgrounds located near the docks expose children to polluted air. Similarly, in the port city of Marseilles, France, the shipping industry, including cruise ships, contributes to 10% of the city's air pollution. Other major port cities like Liverpool and Grimsby are also significantly affected by emissions from the cruise industry.

While there have been efforts to reduce air pollution from cruise ships, such as using alternative energy sources and implementing emissions tests, the industry remains largely unregulated. The environmental impact of cruise ships on port cities underscores the need for new academic advances, regulatory frameworks, and sustainable practices to mitigate the negative consequences of this booming industry.

Cruise ships' emissions cause serious health issues

While the cruise industry is worth billions and continues to grow, there are increasing concerns about the impact of cruise ship emissions on the environment and human health. Cruise ships emit various pollutants, including sewage, wastewater or grey water, hazardous wastes, solid waste, oily bilge water, ballast water, and air pollutants such as nitrogen oxide (NOx), sulfur oxide (SOx), and black carbon or soot. These emissions have been linked to serious health issues, including respiratory and cardiovascular illnesses, higher rates of cancer, and even premature death.

Nitrogen oxide emissions from cruise ships can contribute to acid rain and have impacted cities in Europe, with levels equivalent to about 15% of the NOx emitted by Europe's passenger car fleet. In 2019, Canadian researchers found that passengers aboard Carnival Corporation cruises were exposed to high levels of ultra-fine particulate matter comparable to the air quality of some of the world's most polluted cities. These emissions can also lead to ocean and soil acidification, further impacting ecosystems and agriculture.

Sulfur oxide emissions form sulphate aerosols that contribute to health risks. A study in 2017 revealed that Carnival cruise ships alone emitted ten times more sulfur oxide than all of Europe's cars combined. The high sulfur content in the fuel used by cruise ships has been a significant concern, and while regulations have been implemented to reduce sulfur oxide emissions, cruise operators have been slow to adopt cleaner fuel alternatives due to the higher cost.

Black carbon or soot, a product of the partial combustion of diesel and other fuels, is another pollutant of concern. Larger ships, including cruise ships, are the biggest emitters of black carbon, which can lead to respiratory issues and contribute to global warming. While liquefied natural gas (LNG) has been proposed as a cleaner alternative, it has its own drawbacks, including the production of methane, a potent greenhouse gas.

The impact of cruise ship emissions is particularly felt in port cities, where locals and even children in school playgrounds near docks are exposed to polluted air. Environmental groups and governments have implemented emissions tests and fines, and some cruise lines have taken steps to reduce air pollution by adopting alternative energy sources. However, more comprehensive solutions are needed to address the serious health issues caused by cruise ship emissions.

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