Follow-up update on the emissions calculations: what happens when multiple people traveling?

Hello! Welcome, friends :)

It’s interesting how much this previous post generated where I crunched the numbers on the emissions of a trip to Spain from Ireland, using the different options of land-bridge through the UK, ferry to France and drive, the ferry direct to Spain, or flying to Spain. There’s obviously a lot of interest in the topic which is a sign of the times. As one of the main queries to come up off the back of the discussion was around one specific topic, I thought I’d update here separately.

The main query came to be around the CO2 numbers I used and one specific item. Were they for the whole vehicle, or per person? It turns out, the answer is that it depends! In a car, it’s for the whole vehicle, and if you’re flying, it’s per person. That changes things quite a lot, especially if there’s more than one person travelling. Firstly, one item to highlight: many pointed out that the per-person emissions for vehicle transportation then get way better as it’s only half the output if two people in the vehicle. That’s correct but also misses the point that there’s still the same amount of emissions (if not more, as because of an extra person in the vehicle, it’ll slightly worsen the fuel economy).

So, what I’ve done instead is crunched the numbers again, but this time doing cumulative calculations. What happens straight away is if everyone flies, the emissions output is horrendous as every person doubles the carbon emissions. Ouch.

So, what you’ll see above is all the various options below. The four orange bars on the right are for if it’s two people, three, four or five people flying. As you’ll see, it just keeps climbing. The key piece from this is to recognise that every flight is a LOT worse. (Note: for the vehicle numbers, I’ve made them all slightly worse also to account for extra people in the vehicle - it won’t be perfect, but it gives an idea.).

Green bars: ferry and ELECTRIC vehicles

Blue: ferry and DIESEL vehicles

Orange: flying

Really though, this is hard to compare as there are too many permutations. However, look at the worst and the least offenders: flying five people would be a sixteen-fold increase in emissions. Even if vehicle emissions were made worse to account for five people in a vehicle (I’ve only increased the numbers by around 15% to account for 2-3 people in a vehicle, it would still be a lot worse.

Looking at Two-Person Trips only

Now, for many people I know going on trips, it’s two individuals: a couple who can justify those sort of climbing trips. So, here it is separated out to show just two-person trips. What becomes really clear is that going from a vehicle/ferry option now is significantly worse as you’re essentially doubling your emissions. In short, the driving/ferry is a much smarter approach. What is also clear is just how good electric is from a CO2 emissions perspective. At the leanest option, you’re at one-sixth the output. And that is only the vehicles being electrified. When the ferries also take the step away from burning fossil fuels, expect another step change (electric ferries already exist on short-distance trips in various places worldwide, and I can envision the Ireland-UK trip being viable in the next couple of decades with an electric ferry).

Reflections

What will be interesting to see if it causes anything to change, however? Do you think you’ll stop taking trips after seeing the numbers? Before I started writing this post and I was thinking my answer was “of course we all are, we’re all going to start being responsible!”. However, as I started writing this post, I realised I’m coming to a different conclusion: when given access to possible options like a trip to a foreign climate at affordable prices, who would say no to going abroad on a trip?!

Plus, individuals will look at the two main criteria: time and money. If you take the ferry to Spain from Ireland, it involves at least two days worth of travel, each way. And if you’re only going away for a week, that doesn’t make any sense whatsoever. So, what I do think will happen is there is a reduction in perhaps the odd weekend breaks, but longer trips will continue unabated. And so they should! There is an amazing planet out there to explore. Financially also, people will go for what they can afford.

Of course, if they do, that then incentivises us, even more, to look at solutions to make the energy efficiency and energy usage of every transportation option as ‘clean’ as possible. Imagine when we’re all in electric vehicles (in 30 or so years), and ferries have been electrified, as well as short-haul flights. In that case, we’re in a much better situation than now. What is becoming very clear is that we NEED to rush to electrification, namely as we can generate electricity through renewables and nuclear, neither of which generate CO2.

Personally, I’m optimistic about society going forward. I believe we’ll start to generate incredible changes in the coming decade to improve our emissions output. It’s going to be tough, and we’re going to have to all step up financially to upgrade various systems (home heating, vehicles, etc.). However, the benefits aren’t just emissions. I had the pleasure of driving an electric vehicle for a day in early January 2020. The part not spoken about? Their silence. And when everyone is in an electric, try to imagine what the city will sound like. Another net positive….. It may not be anywhere near as important as carbon emissions, however, it' will be something beneficial to all. We’re going to have to deal with a pile of issues due to global warming caused by all our emissions outputs (and if I owned a house only a few metres above sea level, I’d be selling up) however, I’m optimistic that society will learn to adapt.

It had just better start happening soon.