Leading article: The real cost of flying

As the debate over Conservative tax policy heats up, we are getting more and more hints that some form of aviation tax will be included in the party's final proposals. David Cameron's transport commission is reported to be considering a levy on short-haul flights. A similar proposal is likely to come out of the Conservative environment commission. And yesterday the shadow Chancellor, George Osborne, asserted unequivocally that "green taxes on pollution will rise" under a Conservative government. It will be difficult to take the party's environmental credentials seriously if they ultimately fail to recommend a levy on aviation, the fastest rising contributor to global emissions of greenhouse gasses.

It has long been clear that two political conditions are necessary for concerted action on aviation. The first is a Europe-wide agreement to confront the problem. Budget flights are a European phenomenon, and must be tackled as such. The second condition is a cross-party consensus on the need for action at home, to avoid one party attempting to attract votes by appealing to the narrow self-interest of a section of the electorate.

We are seeing some welcome movement on the first front. The European parliament has voted in favour of a levy, and France proposed a tax on aviation fuel at last year's G8 summit in Gleneagles. Movement is visible at home too. Earlier this year the Liberal Democrats proposed an aviation tax on each flight. The Tories are finding it difficult to avoid following suit. All this is ratcheting up the pressure on the Government, which for all its green rhetoric has too often displayed a woeful timidity on the environment. The sole government policy with respect to aviation pollution at present is that it should be incorporated into the European Emissions Trading Scheme. No one seriously believes this will reduce emissions sufficiently in the long term.

An aviation tax would undoubtedly be painful. A huge number of us have taken advantage of the rock-bottom prices offered by budget airlines in the past decade. A tax on aviation would inevitably push these prices up. Yet to allow the present growth of air traffic to continue would be far more painful. The dire warnings of the direction our planet is heading continue to roll in. As we report today, a prominent feature of the coming century is likely to be the mass movement of climate change refugees. That should put the immediate benefits of cheap flights into a proper perspective.

We welcome the fact that the politics on taxing aviation appear to be moving in the right direction. Yet whether they are moving quickly enough to avert disaster remains perilously unclear.