Mark Ellingham has made a sizeable fortune from the creation of the Rough Guides to almost everywhere. He is shortlisted for the Royal Society's prize for science writing, for his book The Rough Guide to Climate Change.

Now, in a conversion that would command the admiration of St Paul, he declares that "binge flying" constitutes a huge threat to the global environment. "If the travel industry rosily goes ahead as it is doing, ignoring the effect that carbon emissions from flying are having on climate change, we are putting ourselves in a very similar position to the tobacco industry."

He readily admits the irony that he, of all people, should articulate such a warning. He appeals for moderation, for setting some limits on our insatiable appetite for travel: "We now live in a society where, if people have nothing to do on a Saturday night, they go to Budapest for 48 hours. We fly anywhere at the slightest opportunity, 10 times and upwards a year. This needs to be addressed with the greatest urgency."

Environmentalists would say that Ellingham is stating the obvious, adding of course that it is pretty rich coming from him. I am full of admiration for his frankness, however. Almost all of us are hypocrites about climate change. We know that it is real, and desperately serious. Yet we are in a shocking muddle about how to relate our personal behaviour to the phenomenon.

For those who inhabit the developed world, opportunities for travel represent the most significant new personal freedom of the past half-century. Even as recently as the 1960s, hitch-hiking to Greece and Turkey was a big deal for the adventurous young middle class. Africa and Asia were high-ticket destinations, South America and Australia almost off the map.

Today, it is possible to fly almost anywhere for a few hundred pounds, and we all do. Every arriving jet at Nairobi or Ho Chi Minh City or Buenos Aires disgorges its crowds of package tourists and backpackers. Short breaks, which mean intensive plane use, are booming. Short-break destinations include Capetown and Dubai.

Common sense tells us that all this is environmentally disastrous. Yet common sense also tells us that tourism is doing great things for the economies of poor societies all over the world. Carbon emissions soar as a result of flying flowers and vegetables to Europe and America from Africa and Mexico. Yet if that traffic stopped, millions of needy people in the growers' trade would suffer.

All this leaves many of us as confused as Ellingham. Relatively speaking, the travel boom has hardly started. In the decades ahead, many more millions will possess the means and the desire to fly further and more often. The Chinese, for instance, have only just begun to discover the joys of holidaying abroad. Suggesting to people who live in newly emergent economies that they should forgo travel is comparable with the modern western enthusiasm for saving Africa's great animals, after slaughtering them wholesale for a century or two.

Even in the west, it is dangerous politics for a government to seek to check the electorate's passion to fly, just as few democratic nations dare meddle with the freedom to drive. All credible curbs must be based on pricing. Yet if it becomes harder for the poor to travel while the rich stay airborne, this does not sound good on the hustings.

The best and simplest way forward would be to tax aviation fuel, to end the crazy anomaly whereby moving a plane is cheap, while driving a car is expensive almost everywhere in the world save Iran and the US. But it is almost impossible to reach an international agreement on taxing aviation fuel that would stick. No government will act unilaterally, with the prospect of watching its aviation industry migrate elsewhere.

Ellingham suggests a £100 "green tax" on tickets for all flights to Europe and Africa, £250 to more remote destinations. The first benefit of this would be to deter short-haul flying within the UK. It is absurd that it costs far more to take a train to Newcastle or Edinburgh than to catch a plane there. Lots of us, including me, love trains and are only deterred from using them by the cost.

Some destination countries would benefit from discouraging low-budget travellers, because the environmental costs which their visits impose outweigh the cash that they spend. The Samburu National Park in Kenya is currently threatened by the building of two 500-bed hotels. Samburu is a small area, famous for its elephants. Tourists in such numbers will overwhelm its fragile ecosystem. Any rational long-term view of Samburu's interests would come down against the new hotels, and in favour of extracting more money from fewer tourists. The projects will go ahead only because a handful of people will profit handsomely from their construction.

The low-budget traveller creates dilemmas for destinations all over the world. The mayor of Venice, Massimo Cacciari, wants a levy of €1 a head imposed on the 20 million tourists who come to the city each year, to help with the huge municipal costs they impose. Venice is currently struggling to enforce the ban on picnicking in St Mark's Square, and on walking the streets bare-chested or in bikini tops.

If this sounds pompous, the citizens of Venice reply that, at present, a great host of visitors spend next to nothing and conduct themselves in a manner that diminishes the grace and beauty they come to see. Other Italian cities, including Rome and Florence, are drawing up codes of conduct to restrain boorish behaviour by tourists.

Here, it is easy for a good democrat to explode: "Do you want to restrict the wonders of the world to rich bastards?" But it is an obvious truth that the more people who visit a given place, the greater damage they inflict upon it. Ellingham again: "Balancing all the positives and negatives, I'm not convinced there is such a thing as a 'responsible' or 'ethical' holiday."

The bad news for the environment is that it is impossible to believe that the global travel boom will stop. Whatever is done in Britain, or in the western world at large, amid our consciousness of climate change, many other nations which have only just begun to experience prosperity have no intention of depriving their citizens of its privileges.

As with other responses to climate change, however, this is no reason for us to do nothing. Even if the British government is obliged to act unilaterally, it must be right to impose higher costs on air travel through taxation. Indeed, it would be irresponsible not to do so.

Ellingham urges us all to impose some discipline on our own travel, refusing to succumb to "binge flying". Only a minority of thoughtful people, the same kind who buy organic products, are likely to heed him. Most of us change our bad habits only when we are made to do so. We will fly less only when it hurts our pockets too much to fly more. Ellingham is surely right that this must be made to happen, and all credit to him for saying so.



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