Leading article: It is plain and simple... this aviation boom threatens the world's future

It would appear that air travel is about to receive a significant shot in the arm. From this month the European Union's "open skies" agreement comes into force, which means any European-based airline will be able to fly from any city within the EU to any city within the United States, and vice versa. This will mean a host of extra transatlantic flight routes. This follows the opening this week of a new Norman Foster-designed terminal to serve Beijing airport. And closer to home, Heathrow Terminal 5 is due to open later this month too.

We are living in an age of accelerating demand for air travel and these new terminals and international agreements are its fruits. But there are other, less palatable, fruits too. We got a taste of a growing backlash against the aviation industry this week when protesters managed to climb on to the roof of the House of Commons and roll out banners objecting to plans for a third runway at Heathrow. Then there is the growing evidence of the environmental harm inflicted by this industry. Aviation is the fastest growing source of greenhouse gas emissions. And the contrails left by planes are particularly damaging to the global climate. In the opinion of many scientists, we can either have international aviation growth on the present rate or we can have a stable global climate. We cannot have both. At the very least, the present rate of aviation expansion will mean our own Government missing its target of a 60 per cent cut in C02 emissions by 2050.

Many will regard the implementation of open skies as a setback for the struggle to prevent runaway climate change. To some extent this is true. The immediate consequence of the liberalisation of transatlantic air routes will be an increase in the number of flights. But it is important to make some distinctions here. It would have been quite wrong for the EU to have turned a blind eye to the traditional and uncompetitive stranglehold of national carriers on popular routes (in particular New York to Heathrow). Moreover, responsible support for open skies has to be accompanied by pressure on national governments and international bodies to act to reduce overall demand for air travel.

As this newspaper has long argued, the best way to do this is to start taxing the aviation industry fairly and properly. It is time that the price of air travel corresponded more closely with its environmental costs. The fact that airlines, by international convention, have never been subject to fuel tax or VAT has amounted to a vast hidden subsidy to this method of transport and one that urgently needs to be removed. The liberalisation of air routes should actually be complementary to this process. As we have seen in the recent row about energy bills, if there are doubts about the competitiveness of a market, environmental levies imposed by regulators can become discredited by association in the minds of consumers.

Thankfully, the issues surrounding the proposed extension of Heathrow airport are much more straightforward. The Government should be blocking Heathrow from building a new runway on international environmental grounds. Incidentally, a ban on all UK airport expansions should also help to mitigate the environmental impact of open skies. If the number of landing slots at Heathrow does not increase, there is a clear limit on the number of flights that can pass through the airport, no matter the identity of the carrier.

Open skies, resistance to Heathrow expansion, aviation taxes: there is a common theme here. It is time for governments to stop mollycoddling the airline industry and to get serious about curtailing the sector's greenhouse emissions.