The water at the historic Bad Utoquai, an outdoor bathing facility on Lake Zurich,  gleamed turquoise and all I could think about, as I entered it, was that I would never have ended up there if I hadn't taken the train. 

I’m just back from Bergamo and Lake Garda, and one of the biggest thrills of the holiday was the rail journey.  I could have got there faster than its 36 hours but that would have meant skipping so much fun and serendipity.

You can do the budget flight from Edinburgh to Bergamo in just over 2 hours 30 minutes, sending out 0.275 tonnes of carbon dioxide and setting you back anything between a minuscule £17 and a significant £300 at this time of year. Costs of trains for the same journey fluctuate wildly too, but I am sure there is not a date on which you can do it at less than ten times that cheapest air price.

According to my own calculations, the emissions produced on that rail route are less than a tenth of those created by flying. In other words, for the financial cost of one train trip to Bergamo, an individual could do at least ten flights or more, creating over 100 times the emissions. Whilst I’m aware that no one would do that, it does show how, pound for pound, plane travel as a system is many times more destructive to the planet - in this case at least 100 times more.

One study of internal flights and equivalent train routes in France found that flying was between 22 and 84 times worse in terms of emissions than taking the train.

But my point here is not to juggle numbers, but to extol the joy of rail – and to say, if you can afford it (many of us can’t), it’s worth going the extra mile and pound.

When I booked in late September for October half-term neither the cheapest train tickets nor cheapest flights were available and what I got was a rail journey at 3.5 times the cost of the available flight.

My chosen route was Edinburgh to London, London to Paris, Paris to Zurich, Zurich to Milan and on to Bergamo. There were many things I liked about it. One was that it allowed me to stay with a dear friend in Paris (without this connection the trip would have cost still more). Another was that it took me to Zurich, a city where I could, during a three-hour stopover, take a dip in Lake Zurich with a German swimmer I had met in the Scottish Highlands.

In the end, the trip brought many more pleasures. There was, for instance, the old friend, Rhiannon, spotted at St Pancras with her son. I hadn’t seen her for many years, but, as we chatted, we slowly realised that not only were we taking the same Eurostar, but the same 7.22am from Paris to Zurich and then the same train too from there to Milan. She was, it turned out, going onwards again, to Greece, via land and sea, dwarfing my own epic journey by days and many miles - and all because of the climate.

I was relieved to find someone doing something similar. Up until then, I'd been feeling like a lone climate weirdo. People talk about flight-shaming, but there’s also plenty of ridiculing of people who don’t fly (and I do sometimes fly) for being foolish, idealistic or just plain pointless.

Many people tell me that the flight is going anyway, so the seat might as well be used. That is obviously true for any individual scheduled flight, but there’s no way that over the long term, airlines would carry on sending up planes if everyone decided not to take them. The "it’s going anyway" logic here feels like a collective myth we convince ourselves of in the face of the widely reported truth that we are still a long way from creating zero-carbon air travel.

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I recognise, of course, that  I might have more actual emissions impact through campaigning around air travel policies and arguing for systemic change: the frequent-flyer levy that would at least start to help reduce emissions whilst also setting out a path to a future in which flight is not just a privilege of the rich; the tax on kerosene, the possibility of following France’s lead and raising taxes on flights to pay for trains.

You could also say that my overland trip was just an attempt to salve my conscience (especially as the rest of my family flew). Or that it is an unaffordable middle-class privilege, resented almost as much as the more ubiquitous rich-person's privilege of flying as much as they damned like.

But for me this trip was also about something else; the attempt to create an adventure out of finding low-carbon options.

Slow travel is full of delights. The highlight was the Zurich lake which turned, as we swam, to slate-grey, rain bouncing like diamonds. "Temperatur," on the sign outside, "Wasser: 19, Luft: 20."

Of course, I could have stayed home and dipped in a lovely loch producing still fewer emissions. And perhaps that will be my choice next time – or what my bank account demands.