The decision to go ahead with the third runway at Heathrow was taken two years ago; Chris Grayling’s confirmation yesterday marked the point when it seemed to its promoters that enough of the opposition on the ground had been defeated, so it was safe to proceed with a final vote in three weeks’ time. If that is won, and all goes according to plan, the bulldozers will go in around 2021, when the inevitable cycle of cost overruns and slipping deadlines can begin, 31 years after the project was first mooted. By then the UK may be two years into a lengthy “transitional” post-Brexit period, and the bright economic forecasts which are used to justify the plan may be no more use than hot air balloons.

There is a case that air travel has made life better for many people and that more of it would continue to do so. Nearly two-thirds of Heathrow’s present traffic is leisure flying. Mass tourism has boosted the economy of many countries and greatly enlarged our experience of the world, and perhaps our sympathies as well. However unpleasant the experience of a modern airport can be, through which we are run like rats in a maze of shopping malls and security checks, it still seems better to many of us than being trapped in our own countries all year round. Heathrow as it stands today is an unimposing portal to Britain. Failing to expand it is simply sabotaging the country. Beyond that, the country is dependent, like all others, on air freight. So the plans for expansion are in some ways well motivated. We can even overlook the fact that they are promoted by Mr Grayling, a man notoriously unable to make even trains run on time.

Much of the opposition is simply nimbyism. Those West London Tory MPs who claim to be opposed to Heathrow’s third runway on environmental grounds, and then propose that it be built onto Gatwick or Stansted instead illustrate this clearly. There is some amusement to be derived from the rumoured machinations to allow the foreign secretary (the MP for local Uxbridge) to be out of the country on the occasion of the vote, so that he does not have to live up to his stated determination to oppose it even if he has to lie down in front of the bulldozers, but this is a frivolity, like most things about Mr Johnson. The serious objections to the plan remain, as they have been for most of this century, the environmental ones. The simple fact is that it is impossible to combine a commitment to reducing greenhouse gas emissions by 80% by 2050 with the strategic encouragement of air travel.

Mr Grayling’s statement made much play of technological advances. Aircraft will be quieter, cleaner, and greener, he said. It is entirely possible that they will be quieter, and the promise of an enforceable night time curfew when even the quieter planes will be silent must have done much to still some of the opposition from under the flight path. But the lasting damage the planes do is silent and far from the airport. It is their emissions in the upper atmosphere which drive climate change and all its disastrous effects. Nor can those be confined to the poorer parts of the world, as we’re already seeing. As the world warms, the price of mass tourism will be paid in mass migrations. It is true that aircraft have got lighter and more fuel efficient, but this is of no benefit to the environment if there are more of them, flying more often – and that is the underlying logic of the Heathrow expansion. In the long term, which gets closer every day, the only answer to the problem of fossil fuels is to keep them in the ground. Doing so demands that we keep aircraft on the ground as well. MPs should reject this plan when it comes to the vote.