There are many reasons not to fly, not least because the experience can be truly awful. And in the near future it will not get much better. Airports are more congested and planes fuller than ever. Delays are almost inevitable. And none of this is any good for the environment. Although aviation accounts for only around 2% of manmade carbon dioxide (CO2) emissions, that proportion is growing rapidly.

Choosing to fly less can make a small, personal contribution to doing something about this. But it will not make much difference. Two billion passengers worldwide flew last year and another 500m will by 2010. By then, Asia will have become the biggest single air-travel market in the world, giving credence to the theory that it is growing wealth, rather than cheap fares, which is the real force behind the relentless growth in air travel. After all, travel invariably involves other expenses, such as hotels, car rental and dining out.

In a study last year, Britain's Civil Aviation Authority found that overall growth in air travel has not accelerated since the emergence of low-cost airlines in the 1990s. Rather, the budget carriers have taken business away from established airlines in a market that was growing anyway. The biggest losers have been the charter airlines, which once flew millions of northern Europeans to the south for package holidays. With the web, putting together your own holiday has become easy.

Fares of only £10 to Spain might seem like an extravagant waste of jet fuel, but these come-ons should be seen for what they are: a marketing exercise. Try to book one at the start of the school summer holidays. That low-cost airlines are among the most profitable in the industry shows they are not giving much away.

Low-cost carriers are, in fact, the greenest. Airlines like Ryanair, easyJet, JetBlue in America and Malaysia's AirAsia, operate some of the world's youngest aircraft fleets, so they use much less fuel than the 20-year-old kerosene-guzzlers still flown by some long-established airlines. And because their planes carry relatively more passengers, they are the most efficient and thus cleanest way to fly.

Low-cost carriers and their passengers could do more to fly greener. Bringing fewer bags would help. Some budget carriers are trying to dissuade people from arriving with bulging suitcases by imposing extra charges. And do people really need to lug so much "duty-free" onto flights? Just 1kg less per seat can save some 40,000 litres of fuel from an airliner over a year.

Airlines with big business-class and first-class sections are, in terms of pollution-per-passenger, the dirtiest way to fly. Most inefficient of all for the environment is the executive jet (average passenger occupancy in Europe: two). So celebrities who espouse environmental action should match their words with deeds - and put up with narrow seats and the hoi polloi.

Future technology will steadily make air travel cleaner, but as my special report for the Economist shows, even with today's technology, a combination of new aircraft built from lighter materials, the latest fuel-conserving engines and a series of more efficient operating procedures, could cut airlines' fuel consumption by half - and reduce CO2 emissions by a similar amount. And a more efficient industry would also make flying less of a hassle by cutting down on delays and congestion.

So what is delaying this? Governments need to take action over things like the failure to reorganise Europe's air-traffic control system, which is supplied by a ridiculous 34 different providers organised largely around national boundaries instead of just one as in America. The resulting delays and longer routings in Europe cost airlines €3.3bn ($4.4bn) a year. Other fuel savings could be had from more direct air routes between countries. These may save only minutes, but each minute reduces aircraft fuel consumption by 60 litres and saves 160kg of CO2. And many airports are inefficiently priced, with established airlines claiming "grandfather" rights over scarce take-off and landing slots, which, if auctioned to the highest bidder, might be used by carriers that would make better use of them.

But the most important thing governments could do is help an industry that is some $200bn in debt become more reliably profitable. As with the low-cost airlines, it is profits that pay for new, cleaner aircraft. That means more open-skies agreements, more privatisations and letting failed airlines go bust rather than keeping them propped up with state support or, as in America, with the liberal use of the Chapter 11 bankruptcy code. Laws preventing foreigners from taking over airlines need to be abolished.

The low-cost carriers are already itching to have a go on long-haul routes and in overseas markets. To help clean up aviation, they should be given every opportunity to do so.

For The Economist's full report on air travel, go here. And to hear an interview with Paul Markillie on issues raised in the survey, go here.