HEATHROW or Gatwick? That was the question. That was the only question.

To be fair, the Airports Commission which reported this week was given a clear steer by the UK Government. Its job was not to look at the pros and cons of aviation expansion, but rather to choose between expansion options. It was not to examine alternative economic priorities, or to question whether ongoing aviation growth was itself sustainable.

It certainly wasn’t to let something as trivial as the global climate crisis get in the way. Even a generous reading of the cursory treatment the final report gives to carbon emissions from aviation shows that this was never a serious consideration.

The Commission was told to go away and only come back with a recommendation about where to build, and that’s exactly what they did.

It seems unlikely to do what David Cameron hoped for, and take the political sting out of the decision. It will ultimately still be his government’s decision which overturns his previous unequivocal promise to oppose a third runway at Heathrow. The households which are already receiving threats of compulsory purchase orders on their homes will know who’s to blame. With the current London Mayor the likely next Tory candidate for that office and several prominent cabinet members all lined up against the scheme, there will still be a battle to be fought.

Those who want to protect their homes and local communities from noise, air pollution, traffic chaos or outright destruction will make their stand and the climate campaigners will stand with them.

While the Commission’s report blithely dismisses the increased emissions from growing aviation levels, it’s clear that the consequence of this decision will be to put hundreds of millions of tonnes of additional greenhouse gas emissions into the atmosphere,and that’s before you add in the extra damage done by emissions at altitude, so-called radiative forcing which amplifies aviation’s contribution to climate change.

In the long term drive to decarbonise our economy, air transport is one of the toughest challenges. A great deal of surface transport can eventually be electrified. Towns and cities can be made better for walking and cycling. We can improve planning and public services to reduce the need for long commutes. But unless some radical new technology comes along, air travel will remain an extremely high carbon business.

The industry often argues that planes are becoming more fuel efficient, and that this trend will continue. That might well be the case, but there’s a longstanding problem with using energy efficiency alone to try and cut emissions. Make something more efficient, and it becomes cheaper. When that happens, people are likely to do more of it.

This is exactly what happened with road transport; as vehicle engines grew dramatically more efficient over the decades, fuel consumption kept growing because traffic levels outstripped efficiency savings. The same is happening with aviation.

If demand keeps soaring, technology can’t keep up. So although aviation isn’t the biggest source of emissions, it’s one that’s growing fast and where there are no technical fixes available.

Of course those who argue for an extra runway will make a case that the national economic interest can’t be set aside. Aviation is here to stay, they will argue, its growth is critical for businesses, and the alternative is to allow it once again to become the preserve of the rich.

This is part of the case the Scottish Government makes for aviation growth too, though in its case financial incentives are the mechanism for stimulating extra flights, rather than infrastructure capacity. Successive Scottish administrations have subsidised the industry to create new routes (despite the massive tax breaks aviation already enjoys) and the current Government proposes to scrap Air Passenger Duty (ADP).

It took well over a year of pressure from the Greens to get them to admit what should be obvious, but what they had tried to deny – that this policy will also increase carbon emissions.

An alternative does exist. A progressive alternative which will not restrict flying to the wealthy few, but which will reduce emission levels. It will involve admitting that aviation does not serve everyone’s interests equally, and that most of the growth in passenger numbers is neither from business travel nor from families taking an annual holiday.

Far from aviation growth being good for everyone, around 70 per cent of flights are taken by the wealthiest 15 per cent of the population. Instead of scrapping ADP, it could be replaced by a “frequent flyer levy”, under which people would pay nothing if they took one return flight a year, but after that the levy would rise with each extra flight.

This policy would reduce demand in a socially just way and would help us meet climate targets without turning aviation into a preserve of the rich once again.