Frivolous flying is, like the internet and the mobile phone, a creation of our time. A decade ago, no one would have dreamt of visiting a little-known central European city such as Brno or Katowice for the weekend. Yet with airlines like easyJet, Ryanair and SkyEurope offering flights to places you didn't know you wanted to go, at fares too good to turn down, millions of us are exploring Europe.
Indeed, one of the more innovative ideas from the young and energetic people of the Czech Republic is a rent-a-pal scheme. Anyone without a better plan, which generally means at least one in three of the new arrivals on Ryanair's daily flight from Stansted to Brno, will be invited at the airport to join a local student for an evening in the pub.
Opponents of cheap air travel decry the fact that intra-European air fares have more or less halved in the past decade, and that many passengers have puerile motives for travel. How many people returning home aboard tonight's flight from Brno to Stansted will genuinely have spent the weekend soaking up the culture in the heartland of Moravia, compared with the number who had been swigging cheap beer? Few, I guess, but it's still far healthier than killing each other - which is what, for centuries, the young people of Europe have been condemned to do.
And that plane does not just go one way. Cheap flights allow hundreds of thousands of eastern Europeans to comprehend life in the West at first hand, to appreciate what is good and avoid what is bad. Understanding is the key to peaceful coexistence, and the more that people travel, the broader their minds and the deeper their tolerance. It might look frivolous, but air travel is, in fact, a profound force for good.
The cultural goods and bads of air travel are, as far as the world's climate is concerned, irrelevant. The issue is much more straightforward: aviation adds far more to the climate change problem per passenger mile than other forms of long-distance transport, such as trains.
I think if any of the eager holidaymakers on their weekend mini-breaks to Prague had the tiniest inkling of the disastrous effects their greenhouse gas emissions will have on their own children's lives, they'd think twice before snapping up those dirt-cheap easyJet bargains. Luckily for them a conspiracy of silence operates between the Government and the aviation industry, keeping jet fuel untaxed and off the global warming balance sheets - and keeping the flying public airborne in blissful ignorance.
Even The Independent manages to somehow combine gloom and doom headlines ('Climate change threat to food supply' and 'Climate change wreaking havoc with seasons' are two recent examples) with cheap flights offers for readers, highlighting the strange state of cognitive dissonance that exists within the establishment on this issue.
The Government too is pulled both ways, with Tony Blair denouncing global warming as the greatest threat to humankind, while at the same time encouraging the proliferation of regional airports and forcing through Heathrow's Terminal 5.
New research by the Tyndall Centre released this month shows that this state of denial can't continue for long: the growth in aviation is now so massive that it will on its own wipe out any progress Britain makes towards its greenhouse gas reduction targets. It's time for the Government to pull the plug on cheap flights, and for newspaper travel sections to start touting the benefits of more sustainable alternatives instead.
I assume that the high horse from which you write is your preferred form of transport for going on holiday? Or perhaps you walk or cycle, and either camp or stay in local b&bs? To travel only locally, by human or animal power, and to sleep in low-impact accommodation, is the only truly sustainable form of tourism. Sometimes that's exactly how I travel, but much more often I will fly - even within Britain. I would much prefer to take the train, but the Government's lack of interest in emulating the speed and reliability of the French and German rail networks means that far too often rail is the sub-optimal solution: in other words, it is cheaper and quicker to fly.
You cannot blame the individual for selecting the most rational form of transport for a particular journey. Indeed, market economics insists that they should. And neither can you condemn them for choosing to spend the weekend somewhere new and exciting, rather than at the DIY store, if the price is right for them.
I do agree that the price of air travel is not right, nationally or internationally, at present. The fact that aviation fuel escapes tax is an outrage, and realists among the throng at the Paris Air Show last week fully expect the European Union to impose duty on kerosene within a few years. This week the UK's Federation of Tour Operators will publicise the "hefty contribution" that holidaymakers provide to the exchequer on the average package trip: a princely £24, or five per cent, and it only reaches that much by adding in things such as business rates.
It has always puzzled (and benefited me) that travel is zero-rated when almost anything else you and I buy incurs 17.5 per cent VAT. Certainly, air travel should be taxed - though not by the normal means. The ideal tax is one on every aircraft seat rather than passenger. In other words, when a 150-seater Boeing 737 takes off, the airline has to pay £5 tax for every seat whether or not it is occupied. That way, the one in four seats that, at any moment, are flying around unoccupied, might soon be filled. Airlines should be encouraged to become more efficient by penalising inefficiencies. Newspaper promotions of cheap flights, by the way, are all to do with filling up seats that would otherwise fly empty. As you know, the marginal impact of carrying one extra passenger is negligible. And the more people who fly, the greater the economic and social benefits at the destination.
To tidy up a couple of other loose ends: expanding Britain's regional airports as opposed to concentrating on London lowers the impact on the environment. Surface transport to the airport can be greatly reduced, and the fewer aircraft "stacking" over Biggin Hill, waiting to land at Heathrow, the better. You are quite correct about the Prime Minister's ambivalence on air travel. When Tony Blair opened the Heathrow Express rail link almost exactly seven years ago he revealed that his preferred form of transport between his former home in London (close to King's Cross station, with fast trains to the North-east) and his constituency was flying. His "vision for a 21st-century transport policy" was "to be able to get to Heathrow quickly".
Do you run a car as well as a high horse? If so, perhaps you could pick me up next time you see me hitch-hiking.
Simon, I realise that highlighting your own role in promoting the aviation culture which is aggravating climate change puts you on the defensive, but simply blustering about my supposed "high horse" won't be enough to get you out of the moral hole you have dug for yourself. And I'm afraid there's no way you can talk your way out of it: every time you opt for the plane rather than the train you are helping to consign generations of human beings to lives made immeasurably worse by a destabilised climate.
Call me self-righteous if you like, but yes, I have made the decision not to use air travel for holidays, and as a result have discovered some wonderful places in the British Isles which are almost totally overlooked by your hordes desperate to hot-foot it down to the Med for the sun or over to Brno for the beer.
Yes, travelling by train can be a frustrating experience. But so can being stuck in an airport overnight, as most frequent flyers will attest. And I agree that the current pricing structure is all wrong - why encourage people to make the wrong moral choice by pricing them off the railways and into the skies? It remains far cheaper to fly within the UK and short-haul destinations on the Continent than to travel by train, not just because aircraft fuel isn't taxed, but because in the case of easyJet and Ryanair, the polluter really doesn't pay. The rest of us do - not just in faraway places like Bangladesh and Tuvalu which are set to disappear under the rising seas, but even here in the UK where houses built in flood-prone areas will soon become uninsurable.
So what to do? You suggest taxing airline seats: but simply putting up the price of flights is a regressive way to tackle the issue - it'll hit the poor hardest, while rich businessmen will continue to commute to London from their mansions on the Costa del Sol. I have a much more egalitarian proposal - carbon rationing. With rationing we'd all get an equal right to emit greenhouse gases, irrespective of income, while carbon permits would decline year-on-year to a sustainable level (about one tenth of current UK per-capita emissions, I'm afraid).
Then the choice of how to live your life is up to you: if you want to blow your entire carbon budget by flying from London to Barbados rather than discovering the delights of the Lake District, that's up to you. I promise I won't raise a murmur of protest. And permits would be tradable, so poor people - who still travel far less than the rich - would be able to sell their unused carbon allocation to over-consumers like yourself. This seems to me a much better solution to the climate change problem than banning things and imposing taxes.
Let's respect personal freedom and use the market to help people make the right choices for the future of the planet, rather than the wrong ones.
Simon Calder is Travel Editor of 'The Independent'. Mark Lynas is the author of 'High Tide: How Climate Crisis is Engulfing our Planet' (Harper Perennial, £7.99). For more information about his work go to www.marklynas.org