The Cost of Crossing an Ocean

An abridged version of this article appears in the newsletter Towards Sustainability #7, January 2020.

I started writing this article way back in April 2020 when the world was in a Coronavirus induced state of virtual lockdown, so very few people were going very far at all. At the time it seemed like that couldn’t last forever but here we are nine months later and though many countries did leave that lockdown, plenty have plunged deep back into it again.

We were in Mexico and with a plan to be back to Europe by the end of the year, and we were looking for a way to make that journey with as little environmental impact as possible.

Given all of the negativity surrounding air travel and the fact that it’s widely proclaimed to be the most awful terrible thing for the planet, we thought that the question we should be asking ourselves was:

How do you get back from the Americas to Europe without flying?

But it turns out that isn’t really the right question at all. Bear with me and we’ll come back to that in a minute.

Based on the assumption that flying was the worst thing that we could do, we started looking at the alternatives. Obviously, the huge body of water in the way makes the options a bit limited, you either have to sail across it or fly over it.

The ideal thing would be to pull a Greta and hitch a ride on a super sustainable zero-carbon yacht, but that just isn’t practical for most of us. Even if we wanted to be paying passengers there just aren’t these kind of vessels criss-crossing the Atlantic on a regular basis.

So we started looking at the costs of travelling on a cargo ship, because they are going to be crossing the ocean with or without a few passengers and because cargo ship travel is hip and cool, and makes you look like an adventurous eco-conscious kind of person.

The problem is that travelling by cargo ship turns out to be prohibitively expensive, many times more than the cost of flying, and actually more expensive than actually getting on a cruise liner in many cases.

With that in mind we looked for other possibilities and discovered ‘repositioning cruises’. This seemed like a good idea based on similar logic to the cargo ship, that going by boat must be better than flying, and they are repositioning the ship, so it’s going to cross the ocean even if it is completely empty.

This was actually much more affordable than hopping on a freighter, and so we snapped up a bargain and booked a trip over the ocean back to Europe.

Only after actually booking it did we actually look up the environmental footprint of this travel vs flying which is where it all started to go a little bit wrong…

According to the best calculations I can find, which I will admit are not super new, cruise ships emit around 0.43kg of CO2 per passenger mile, compared with 0.257kg for a long-haul flight. That’s only a small part of the story though, on a typical week long voyage a cruise ship generates more than 50 tonnes of trash and a million tonnes of grey water, 210,000 gallons of sewage and 35,000 gallons of oil-contaminated water. In theory all of this dirty water and sewage is treated before being pumped into the ocean but cruise lines have very shady records on this.

This gulf seems to be widening as well. While planes are becoming more sustainable, lower emission and more fuel efficient, cruise ships simply are not.

Oops, had we made an ecological blunder here?

It seems that cruise ships attract little attention but actually are far worse for the environment than planes are. So, arguably yes we had, I could justify it to myself on some level by thinking about the fact that it was a repositioning cruise, that they are going to move the ship across the ocean whether there are people on it or not. I know this argument was flawed but it’s the best I could come up with.

In the event all travel became impossible at that moment and the journey was cancelled and refunded, meaning that we were free to buy, surprisingly, far more sustainable flight tickets to get home.

The thing is that people are not going to, and in my opinion shouldn’t want to, stop travelling. Journeys across a country or even across a continent can always be done in more sustainable ways; electric or hydrogen powered vehicles, trains, short haul electric flights are on the way. When we reach thousands of miles of open ocean and need to cross it though the options suddenly get a lot more limited, and that is something that we need to change. 

In the days before diesel engines and before flight we somehow managed to cross oceans on ships with sails, they were slow and not always the safest way to travel but they were definitely sustainable, harnessing the power of the wind to move us across the world. Technology has evolved a lot since then and we are getting pretty good at using the wind for power generation, just maybe we need to look backwards a little and apply some modern tech magic to revive the days of sail.

Similarly with flight. I’m not suggesting that we should be looking back to the times of unpowered flight, but we have built planes that all look pretty much the same and are powered by the same basic engine designs for decades. Surely there are advances to be made there?

The answer isn’t to not travel but to do it more thoughtfully, to combine short trips into longer ones and to cross oceans less, and to make the ships and aircraft that carry us across those amazing oceans far more sustainable. It’s a challenge for sure but it is one that we should be more than capable of solving with a combination the best of today’s tech and the best of yesterday’s harnessing of nature.

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