Are Cruise Ships More Polluting Than Planes?


The travel industry is one of the worst offenders to environmental pollution and projections show that it is likely to continue growing.

Planes and cruise ships are popular holiday modes of transport, but do people consider how polluting their choices are?

Luckily we do have alternatives when it comes to planning a trip away, but if you don’t know which options are the most eco-friendly it is pointless! That is why I have done the research and I am going to answer the question of whether cruise ships or planes are more polluting.

Mile for mile, the carbon footprint for a cruise ship is worse than flying. A cruise liner such as Queen Mary 2 emits 0.43kg of CO2 per passenger mile, compared with 0.257kg of CO2 per passenger mile for a long-haul flight.

In the rest of this article I will compare the pollution produced from ships and planes. I will also elaborate on why cruise ships are the most polluting mode of transport, how we can do our part to be more sustainable when travelling,  and ways in which the industries needs to change in order to become a sustainable travel option.

Why Are Cruise Ships and Planes So Polluting?

Greenhouse Gas Emissions

Let’s start with the most obvious one! Cruise ships emit massive amounts of greenhouse gasses per person per mile.

These emissions harm the marine environment and its species. It contributes to warming seas and a decrease in species diversity.

Cruise ships run on massive diesel engines, gas turbines, or sometimes both. The quantity and quality of their fuel is a very dangerous combination.

Cruise ship operators are known for choosing the cheapest fuel on the market and opting to use scrubbers instead of the safer more expensive alternatives. Scrubbers (or the ‘emission cheat’ method) work by cleaning the cheap fuel and disposing of the pollutants directly into the ocean.

It is not only their carbon emissions that are the problem. Cruise ships can also emit large amounts of sulfur oxides and nitrogen oxide which are both carcinogenic substances. In 2017, Carnival Corporation (the largest cruise operator), emitted ten times more sulphur oxide than all of the cars in the Europe combined.

As we established at the start, planes do in fact produce less greenhouse gasses, mile for mile than cruise ships.

Despite being better mile for mile, that does not however mean that they are good for the environment. Planes are a highly polluting mode of transport which still contributes massively to global warming. Global aviation accounts for 1.9% of greenhouse gas emissions and 2.5% of CO2 emissions.

Waste Pollution

Cruise ships produce huge amounts of harmful waste which is disposed of with surprisingly few regulations.

Shockingly, cruise ships can dump their sewage when they are only 3 nautical miles off the coast. This ends up polluting some of the world’s most sensitive and pristine marine environments and harming the species that live there.

Every day a cruise ship can generate as much as:

Waste produced on a cruise ship is meant to be properly separated and sterilized. Then the liquids can be put into the ocean and the solids burnt.

Several cruise liners have been charged with discharging huge amounts of oily waste, grey water and plastic into the oceans. One of the worst know offenders was Carnival Cruise Lines, who in 2019 was fined $60 million for pollution, conspiracy, and lying to the USA coastguards.

Comparatively, planes are much more environmentally friendly when it comes to waste.

All the waste that is produced during a flight is taken back down to ground level and disposed of properly- none of it ends up getting thrown out of plane windows!

But once again this is not to say they are without fault. Flights do produce a large volume of food and plastic waste which is very harmful and unsustainable for the planet.

Airlines generate a scary 6.7 million tonnes of cabin waste every year, 20-30% of which is untouched food and drink. This doesn’t end up directly in the environment like with cruise ships, but it does go to landfill and emit greenhouse gases.

Noise Pollution

Our oceans are becoming louder and cruise ships are contributing to this.

The low-frequency sound waves produced from large ships interrupt communication, impact migration and have a detrimental effect on whole ecosystems due to lowering reproduction rates and increasing deaths.

Marine mammals are vocal creatures that rely on constant communication. The engine noise from cruise ships disturbs species such as whales and dolphins, whose sensitive hearing gets damaged, causing them to become disorientated, sometimes leading to their death.

Now let’s compare that to plane travel. Planes do still produce noise pollution- airports are known for disrupting wildlife and local residents. But unlike ships that cause problems for the entirety of their journey, once planes are in the air, they are too high up to have an impact on people or animals in terms of noise.

Visual Pollution

This is an area that often gets overlooked with cruise ships, but they do in fact have a huge negative impact on the visual aesthetics of a location.

They impose on quaint towns, islands and seaside villages ruining the remoteness and simplicity that people came to enjoy. The more remote a location, the more their massive size looks out of place and ruins the experience.

Once again, this is another area that planes have less of an impact on the environment than ships. Of course airports are not attractive and are unsightly for the residents nearby. But once the plane is in the air, it is so tiny, or often not visible at all.

Is There Really a Winner and a Loser?

Overall, it is clear that both cruise ships and planes are polluting modes of transport. Cruise ships are the more polluting out of the two, so you could call them the loser, but both need to be addressed in order to make them more sustainable travel options.

What Should be Done?

In order for cruise ships and planes to be used as sustainable modes of transport, it is clear that a lot of alterations are required to be made!

If they continue how they are currently operating, it is too much of an unsustainable and detrimental practice on our oceans and the environment.

Regulations

Strict and effective global regulations need to put in place. At the moment regulations are so lacking, especially for cruise ships, that companies end up getting away with a lot of damaging activities.

Regulations should be enforced that are the same worldwide and hold consequences when not followed. At the moment the US water space is much more regulated whereas Europe is very patchy in comparison.

Further regulations could be enforced to encourage recycling and a zero waste approach to waste onboard ships and planes. This could drastically reduce the amount of waste that ends up in landfills.

Technology

The technology is already available to make cruise ships less polluting and more sustainable.

The problem is educating the corporations and getting them to understand the importance of looking after our oceans- even if that means them having to spend a bit more money to do things correctly.

Electric batteries could positively change the whole cruise ship industry. The technology is coming along quickly, so with any luck prices will also begin to drop and make it a more commercially viable option for the masses.

Closed looped scrubbers are another clever technology that cruise ships should use and would make a massive difference to the amount of pollution they produce. They work by storing the waste for treatment to be done safely on land.

When it comes to planes and technology, it is slightly more complicated. Electric planes are not in our near future! The focus will have to be more on carbon offsetting to reduce the impact on the environment.

What are the Greener Alternatives When Travelling?

Try and keep all of this information in mind when you’re planning your next holiday.

Responsible tourism is all about educating yourself and taking ownership of a more sustainable style of travel. There are plenty of options out there and maybe you’ll even get a more exciting holiday because you have made the effort to try something new!

Staycation

Staying in your home country and exploring what you have on your doorstep is of course the most environmentally friendly way to travel.

Over the last year, with so many travel restrictions and lockdowns happening all the time, staycations have become all the rage.

People have come to realize that their home country has some beautiful places to see and you don’t always need a plane ticket booked to have a fun adventure away.

You will be helping the environment, your local economy and getting to know your own country better. Get out your local map and pick a destination that you have never visited before!

Less Polluting Modes of Transport

There are lots of alternative modes of transport that you can use when planning a holiday. You could hire a car and do a road trip! You could try a mixture of buses and trains, or if you wanted to be really eco-friendly, you could go one step further and look into a sailing or cycling trip!

References

The Guardian. 2006. Is Cruising Any Greener Than Flying? https://www.theguardian.com/travel/2006/dec/20/cruises.green

Cruise Ship Pollution: A Tale of Titanic Tyranny. 2020. https://www.geekyexplorer.com/cruise-ship-pollution/#waste

Needless Cruise Pollution. https://usa.oceana.org/sites/default/files/reports/polling_report1.pdf

New York Times. 2019. Oceans are Getting Louder, Posing Potential Threats to Marine Life. https://www.nytimes.com/2019/01/22/science/oceans-whales-noise-offshore-drilling.html

HuffPost. 2020. Airline cabin waste is aviation’s other crisis  https://www.huffpost.com/entry/plane-waste-cabin-plastic-food_n_5e1c5868c5b650c621e1cc89

Ritchie, H., 2020. Climate change and flying: what share of global CO2 emissions come from aviation. https://ourworldindata.org/co2-emissions-from-aviation

Rob Wreg

Rob is the head writer at Innovate Eco sharing knowledge and passion cultivated over 10 years working in the Environmental Sector. He is on a mission to build a community of people that are passionate about solving environmental problems.

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