EACH time the Scottish Government misses another year’s target for tackling climate change, those of us who campaign on the issue scratch our heads and try to decide how to respond: condemn ministers for inaction, or pat them on the back for what’s been done and give encouragement for more? The difficult truth is that both responses are justified – progress has been made in some areas, but in others there is a deep reluctance to make the policy changes that are needed.

Transport is one of the real sticking points. And within that heading, air transport is perhaps the toughest challenge. Cars, buses and trains 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.

Planes can be made more fuel efficient, but as with road traffic that’s not reducing the environmental impact because the number of flights just keeps growing, and engine technology can’t keep up. Besides, if you live under a flightpath the fuel consumption isn’t your biggest problem – many of those campaigning against Heathrow expansion (including MPs who are in the cabinet) are more concerned about noise and health impacts than with climate change.

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. I’ve made this point repeatedly to the Scottish Government when they promote their policy of scrapping Air Passenger Duty. They want flying to be affordable, instead of being only for the rich. But there is no way of squaring that with their own climate change policies.

Or maybe there is. A new campaign has been formed around the idea of replacing APD with 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.

What’s driving the growth in aviation isn’t business travel, or families taking their annual holiday. It’s a tiny wealthy minority of the population who fly far more often than that. It’s reckoned that 15% of the population take 70% of all flights.

Aviation already enjoys huge tax breaks, keeping fares artificially low. Instead of scrapping APD, 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.

When the Airports Commission reports in the next week or two about the options for meeting capacity, the option of preventing endless aviation growth must be on the agenda.