All vehicles that ply the face of the planet produce some form of pollution, mainly from the exhaust gases which they empty into the atmosphere. Whilst the number of cruise ships plying the world compared to cars, the most common form of transport in the world, may seem insignificant, they are actually a big contributor to atmospheric pollution for the simple fact of their size. Each cruise ships is like a floating city, and produces a similar amount of waist. With their enormous diesel engines, a single cruise ship is capable of producing the same amount of pollution as thousands of cars in a single day, and the engines are rarely, if ever stopped, even when the ships sit in port due to the length of time it takes to start the ships’ engines in the first place.
As cruise liners run on diesel engines, the main gases which they produce are carbon monoxide, sulphur dioxide and nitrogen oxide, as well as carbon dioxide. These are all the main contributors to Global Warming, with sulphur dioxide further affecting the acidification of precipitation, resulting in acid rain. The fact that cruise ships produce such high levels of exhaust gases is because the oil used for ships’ engines has a high sulphur content. As such, cruise ships are responsible for some of the most harmful exhaust emissions, and an especially bad culprit in the production of carcinogens, harmful to humans. This is a particular problem for the air quality of popular tourist destinations such as the many ports dotted throughout the Caribbean, as so many ships visiting the same ports has a great effect on the pollution of the air in each of the localised areas where ports exist. Added to the exhaust emissions are the fumes given off by the incinerators used to destroy the each cruise liner’s garbage, which often includes the burning of plastics, producing even more greenhouse gases.
The problem of the emissions from cruise ships is recognised however, and steps are in progress to reduce the pollution they produce, as well as the imposition of standards to which all cruise ships must adhere.
Ships measure their carbon emissions on a per passenger basis. This carbon level has been steadily decreasing as new technology is installed on cruise liners, effecting both the engines of the ships as well as the design of the vessels. To economise on how much power is used to propel a vessel, these measures include more streamlined hull designs, to reduce the friction of the water around a ship’s hull, creating a reduction in power requirements. This is called hydro-dynamics, meaning how well the hull disperses the water along its length. This is further helped by the application of coatings to reduce the hull’s resistance to the water.
Much like in houses, Cruise Liners have are also being made more efficient in terms of how their heating works, so that more heat is retained and reused, together with the same measures being applied to ventilation and air conditioning systems. Again, like in houses, to make sure that no more energy than is required is used, even the windows of cruise liners are being made to reflect sunlight, so that no more air conditioning than necessary is used.
More importantly, the engines being installed in newer vessels are a combination of diesel and electric power plant, which allows a vessel to shut down any surplus systems or surplus levels of power. The use of scrubbing technology is also being expanded to further reduce the amounts of carbon monoxide and sulphur dioxide each ship releases into the atmosphere. There is also an expanding trend towards the use of renewable energy such as solar panels on ships.
To ensure that a ship meets the standards of acceptable pollution levels, relating to waste dumping as well as air pollutants, there are rules laid down by the International Maritime Organisation which sets strict requirements for cruise line pollution, the standards of which must be adhered to, with each ship receiving an International Air Pollution Prevention Certificate if the standards are met. The requirements are called the International Convention for the Prevention of Pollution from Ships, and every nation to which the cruise ships are registered must ensure that these standards are met.
Even with the measures in place however, cruise ships will continue to be a large contributing factor to air pollution. Just how significant their emission production levels are is hard to ascertain for just cruise ships, as all other ships add to the problem also, but in localised areas around the ports where the cruise lines dock, the problem is pronounced enough to have become a familiar issue reported in newspapers around the world as the governments of countries or states push to have the situation improved. Examples of this are concerns raised by Arnold Schwarzenegger about the effects of cruise ships on California in 2002, and the problem is also very widely covered in the Alaskan press.
Essentially however, like with all other means of transport which produce greenhouse gases, the problem will of air pollution caused by cruise liners will not be solved until alternative power sources are developed and put into production.