to squid.conf fixes that error
Well I would say as always that the best and first step is to start measuring these trips, and see how much they contribute to your own personal carbon footprint. There's a zero-order approximation - the simplest one to make - that does indeed say that long-haul trips are bad; not that "people should never travel abroad", but that if they do so then it should be by rail.
But that's all it is: the precursor to your first quantitative approximation. If you want to make cases for this or that journey, then the truth is in the details, and they will at least help you both make more considered judgments on when to fly, and also make a moral case for the flights you do take. And then, unless you're sticking to that zero-order approximation - which, incidentally, I've found perfectly practical to do - "never" is an odd and (possibly intentionally) emotive word to use: how often can one's own biomass budget of 5 tonnes take a 1-tonne flight? A 2-tonne flight? A 3-tonne one? Every year; every two years; every five years? Only with good data can you make hard decisions.
As an aside, really... when it comes to thinking about what journeys we do and don't "need" to do, I'm always reminded of the fact that it's only been the last thirty or so years that we've felt that aeroplane journeys are something that a middle- or greater-class person can or should (or need to) make with any frequency.
Qualitatively, you can look at the way that Victorians, or even early 20th-century people, who in theory had the technology at their disposal - felt about transport outside their own country. The practicalness of arranging their lives around frequent, long-distance travel would not strike them at all! Quantitatively, if you take a conservatively short measure of civilization as a whole (beginning 4000BC?) then that means that only for the most recent 0.5% of the timeline of civilized humanity has this been in any way sensical. So this notion, of plane flights for all (although the rich still fly the most) is in both qualitative and quantitative terms a culturotemporal blip.
In terms of making people change their habits more generally, there's a lot that can be done in terms of personal forms of carbon allowances and trading, but there's always criticism towards them, and not necessarily from the expected sources: such schemes can end up putting a price on the priceless, and give licence to the rich to buy carbon allowances from the poor. They would also eventually - almost by definition - raise the price of your transatlantic trips to the point where you might eventually feel you don't need to make so many after all.
And ultimately, we might find that the only trips that actually need to be flown - in the true sense of that word - constitute actual medical emergencies, involving oneself or one's family. The rest become - or maybe they always were, but we were borrowing against our own futures - only occasionally affordable luxuries.
I agree that at face value your example does seem to show a marked favouritism towards aviation, and some of that is definitely because the plane companies don't pay their fair share of tax, and also misrepresent their prices. I'm generally of the opinion that short-haul flights should be environment-taxed into oblivion, if only to finance reparations of the comparatively enormous environmentaly damage that future generations would otherwise have to clear up with no assistance.
I don't want to get too hung up on transport, though. It's definitely important, not least because it contains some problems that are intractable under an approach of gradual personal reduction; but there are two or maybe reasons why there's a limit to the usefulness of tracking down your specific example.
But firstly, travel is only the fourth biggest of the five main contributions to the average UK carbon footprint. In terms of tonnes of CO2, these are as follows:
So travel is important - they're all within around 1.5-3 tonnes, after all - but it's by no means the most important. And secondly, your specific case hides a more complex issue, so while I'm would be the last to cry "apples and oranges!" there's clearly more at work than just comparing one journey with another (are all your costs return journeys? I think so, but it's not clear.)
We could talk about it in a lot of depth even so, although I only have so many hours in the day! Suffice it to start by saying that, as I'm sure you're aware, the UK's rail system is more confusing and complicated than most others in developed countries. Off-peak returns are a specific sort of semi-flexible ticket; if you book tickets for specific trains - which is a closer analogue to the specific plane journey - then you will almost always get cheaper.
Furthermore, if you split your journey at the boundaries formed by rail franchises - so-called "split ticketing" - then you can reduce the cost even further. This is because when you purchase multiple franchises' services through an agent, they add often exhorbitant fees to the result. Without reference to up-to-date prices (some of them are a few years old) then Edinburgh to Oxford's £33.50 advanced single - which is considerably cheaper than half of your £121 off-peak return from London - can be reduced to £27.50 by buying three tickets, splitting at BNS and Banbury. Oxford to Cardiff is nearly 50% cheaper simply by purchasing different tickets; and many other fares can be similarly reduced.
So it's complicated; the problem remains, of course, that all this depends on knowing what you're doing, and stressing over split journeys; it's not common knowledge and [edit for sense: that definitely means that culture favours aviation.] So I broadly agree with your primary thesis - on transport - that there needs to be some kind of government intervention. But tricks like split ticketing show that the intervention need only be fairly slight, if correctly targeted: although I've yet to find anyone outside of rail company shareholders who wouldn't be happy with renationalization tomorrow. If anyone wants evidence of political will for transportation change in the direction of sustainabilty, there it is.
(Not to mention that I couldn't get a train between New York and London if I tried - some trips need to be flown, and I don't think it's practical to say that people should never travel abroad.)
Fantastic post. Thanks for the really thoughtful reply!
What's interesting is, I don't think our posts are contradictory at all. In fact, I think we're coming from very similar perspectives (our post titles aside). Your focus is more on personal changes; mine on infrastructure changes.
Regarding flights vs trains, the last-minute price discrepancy is certainly true. But there's no reason in the world why that couldn't and shouldn't apply to trains too - the fact is (and I've just checked this, via Skyscanner and Thetrainline), an off-peak return between London and Edinburgh is £121 by rail if I want to travel tomorrow, and exactly the same price if I travel in November. Flying from London is £55 in November - and £125 if I travel tomorrow. If anything should be £55, it should be a trip on public transport.