A rise in commercial shipping and cruising for pleasure has not only placed pressure on the seas but is polluting the air we breathe. What’s being done about it?

Sectors from agriculture to retail are pushing international trade to extremes, while cruise holidays are accelerating in popularity. 

Studies estimate that current shipping activities contribute 11% to global carbon emissions and identify them as the least regulated source of anthropogenic emissions. Ships emit high levels of pollutants such as sulphur oxides (SOx), phosphorus (P), methane and nitrogen oxides (NOx). 

Shifting this hard-to-abate sector to carbon neutrality pre-2050 requires us to ask:

1. Are there any actions we can take individually? And,

2. What are shipping companies doing about it?  

How do cruising and international shipping impact human and planetary health? 

Cruise liners and container ships, like all vehicles, rely on fuel to get around. However, sheer size, resistance when travelling through water and the vast distances covered make fuel use in shipping a particularly acute problem.

Various fuel types, such as heavy fuel oil (HFO) or liquified natural gas (LNG), contain several pollutants considered to be toxic to health. 

In standard fuel, the CO2 released contributes to ocean acidification, global warming and air pollution from port cities reaching hundreds of kilometres inland. 

Perhaps more alarming, however, are levels of SOx. The SO2 levels in HFO are 2700 times higher than in a petrol car. That’s so high that the International Maritime Organisation links it to strokes, asthma, lung cancer and heart disease in humans, as well as an increase in acid rain, fresh water and crop degradation across countries.

If I go on a cruise holiday, how bad is it? What can I do instead?

Having considered these impacts on the planet and our own health, eco-conscious holiday makers may be asking whether this is actually as bad as flying. 

For argument’s sake, we all deserve some hedonism and self-luxury once in a while, but what’s the cleanest and greenest way to do it?

One damning report by the Energy Monitor has found some clear answers; a passenger taking a seven-day round-trip cruise from the UK to Spain, with 3 stops and all food and accommodation spent on board, is roughly three times more carbon-intensive than flying to Spain or France to stay in a hotel instead.

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This intensive form of travel is also found by the International Council on Clean Transport to emit over 850 kg of CO2 per passenger, whereas a short haul flight to the same location and for the same length of time will emit under 250 kg of CO2 per passenger.

Despite initial struggles as international borders closed down, post-pandemic there has been a rise in cruise holidays across Europe, primarily in Italy, which has become the most cruise-ship-polluted country on the continent. 

Despite significant efforts in Venice in 2021 to ban large cruise ships, leading to the city’s drop from 1st to 41st on the list of most polluted coastal areas in Europe, studies still report an overall increase of 25% in particulate matter, 18% in NOx, and 9% in SOx across the country.

With more than 20% of consumers actively making travel decisions based on the environment, we must look to companies for answers on how they will modernise this industry.

What are the current pollution numbers for cruise companies in Europe?

The increase in pollution in Italy is reflected across the continent; SOx reached 509 tonnes emitted in 2022, 4.4 times more than all the cars on the entire continent. Two companies, The Carnival Corporation and MSC Cruises, account for over half of this increase. 

On top of cruising, international trade transports 90% of external freight in Europe. For large swathes of the European population, therefore, shipping pollutants are inescapable. Considering this, one would imagine regulation must have been brought in.

And it was. In the 2020 Global Sulphur Cap, legislators reduced the maximum content of sulphur that could be used in shipping fuels from 3.5% to 0.5% outside of protected areas, which were already at 0.1%. 

Despite this, the consequences of increased traffic left Barcelona as the most SOx-polluted port in Europe in 2022, with emissions still higher than those of 2019.

Additionally, methane emissions — a greenhouse gas 86 times more potent than CO2 — hit 7804 tonnes, with huge implications for the environment. 

With all this in hand, in November 2020, the umbrella company covering 95% of the world’s cruise fleets, CLIA, committed to Net Zero by 2050.

Is the industry behind in the race to Net Zero? 

As transportation technology continues to advance, it becomes clear that, despite Net Zero commitments, the technology needed achieve carbon neutrality in this sector simply doesn’t exist yet. The 2050 promise is, therefore, more of a pursuit or investment highlight than a guaranteed outcome.

One method across the industry has been the introduction of liquified natural gas. As safety concerns surrounding hydrogen fuel’s flammability have mounted, the 20% reduction of greenhouse gas emissions LNG offers became the obvious, safe choice for a quick carbon footprint reduction. 

However, leading climate action groups, such as the Ocean Conservancy, have cast doubt on this replacement’s green credentials due to the huge amounts of methane emitted by LNG.

In the face of uncertainty, it may be of reassurance to know that the CLIA partnered with additional maritime organisations in pledging a $5 billion fund from the industry for the development of technologies for both propelling and streamlining ships and for clean fuels.

Others are directing efforts elsewhere; the cruise liner ‘Royal’ partnered with the Kansas wind farm project, for example, which the company claims will offset more than 12% of its carbon emissions annually. 

An artist's impression of a red, black and white cruise ship sailing across calm waters. The futuristic sails on the ship indicate its net zero capabailities.

(VARD Design/Hurtigruten)

Other companies have focused on battery power with plug-in recharging at shoreside, which may reduce the air pollution felt by vulnerable coastal communities. 

While seemingly a good idea, this on its own has shortfalls, as only 14 of more than 800 CLIA ports have plug-in capabilities, and the weight of battery power in turn means the ship requires more energy for movement.

Naturally, both carbon offsetting and plug-in shore power are not long-term solutions. However, it can be of some reassurance that action has been taken in the short term while background projects occur. 

One example of this is Hurtigruten, a Norwegian travel company that has released its plans for the world’s first emissions-free cruise ship by 2030. Such a ship will use both battery and wind technologies, and harness solar power to operate 50-metre retractable sails. 

As maritime transport is set to increase further, we will have to see if such technologies lead in the future of green travel.

Hedda Felin, CEO of Hurtigruten, puts it like this: “For us to sail for 130 years more, we need to change the way we sail”.