climate change transport

Luton airport expansion and the limits of decoupling

A few weeks ago I was speaking to my MP about the expansion of Luton airport. In an age of climate crisis, how can we continue to drive expansion of such a major source of pollution? At a time when we need to be decarbonising the entire economy, Luton Airport is one of the fastest growing sources of greenhouse gases in the country.

The answer, which we had from both our Luton MPs, is that planes in future will be more efficient. Every generation of planes is 30% more efficient than the last. So that proposed growth in airport capacity doesn’t have to mean an increase in CO2 emissions.

Since this is a common answer that I have also heard from the council and from friends who work at the airport, it is worth examining. First, it is true that planes are getting more efficient:

A scan of the history of commercial passenger planes shows rapid improvement in the early days, followed by slower but consistent improvements in the amount of energy needed per passenger mile. There are further efficiency savings to be had, some theoretical, some definitely on their way. There are reasons to question whether that new generation of planes will make a difference in time, but the bigger issue is whether those efficiencies will offset the growth.

Here we get into the basic conundrum of any decarbonisation strategy that assumes ongoing growth – and of course that’s almost all of them. Governments and businesses want to grow and cut carbon at the same time, and to do that they rely on decoupling: breaking the link between economic growth and rising emissions.

As I’ve described in more detail in previous posts, this only works if you get absolute rather than relative decoupling. It sounds a bit technical, but it’s common sense really. If the economy is getting 2% more efficient every year, but also growing by 3% a year, then emissions will keep rising. This is relative decoupling, and it’s the problem with aviation expansion.

Luton Airport is relying on a fleet of theoretical planes that will be 30% more efficient. But the plan is for the airport to double in size. It doesn’t take a mathematician to work out that even if those more efficient planes materialise, the growth will overtake the efficiency gains. Emissions will still rise.

Right now, every source of emissions needs to be falling. No sector gets a free pass to keep growing its carbon emissions. Luton Airport’s plans are called a ‘vision for sustainable growth‘, but from a climate change point of view that’s an oxymoron. It cannot be sustainable, and also expanding. It will have to pick one or the other.


  1. The situation at Luton Airport is even worse than in that very fair post, for a number of very worrying reasons:

    1) In Dec 2013 Luton Borough Council gave permission for a 15-year expansion project at Luton Airport to double passenger capacity, and the Councillors also voted in a range of planning conditions to ensure that promised mitigations were delivered as well, in order to protect “residential amenity”. This became a legal agreement signed by the Airport.

    2) In Jan 2014 the officers of LLAL, LBC’s airport holding company, put in place a financial incentivisation arrangement for the Airport to grow more quickly – with the result that the expansion has been delivered in just 7 years, and has run far ahead of the mitigations – which crucially included bringing quieter and more fuel efficient neo engines (they’re around 15% more fuel efficient, not 30% as suggested above, and only slightly quieter)

    3) But for every more fuel-efficient neo plane Luton has introduced since 2017, it has also swapped out the same number of smaller inefficient planes for a larger inefficient planes: 5% of the fleet is now neo, but another 5% of the fleet is now standard-engined larger A321s in place of smaller A319s, hence cancelling out the gains

    As a result, the Airport has also broken a noise planning condition as well as not delivering a cleaner fleet – yet both it and its owners want further growth, without waiting for airspace redesign (which would allow planes to climb efficiently rather than being held low for up to 16 miles), or a net improvement in the fleet, or a net reduction of noise.

    As other posts state: here we have a Labour Council apparently absolutely determined that its airport shall expand to the maximum extent possible as fast as possible, and doing everything it can to ensure that happens regardless of the environmental burden, or of the agreements reached in 2013 for a balanced growth and mitigation project, or of the climate change emergency. It’s disgraceful – and Cllr Andy Malcolm of LBC, also the chair of LLAL, needs to be held to account over this.
    LADACAN – Luton And District Associate for the Control of Aircraft Noise.
    (LADACAN is a local community group working with other local groups such as STAQS, STAND and STOPLAE to try to prevent further environmentally irresponsible expansion at Luton Airport)

    1. Yes, there’s lots more to the story. I’m leaving out the local politics because I’m using the airport to draw lessons for a wider audience, but these are very much live discussions in our local Extinction Rebellion group.

      The 30% figure in my article is from our MPs, by the way, not what I think is actually happening! I should clarify that.

  2. Jet engines burn fossil fuels – so I don’t understand why we are contemplating any growth at all. However, our past experience with expansion at Luton airport does not bode well for any future deal that links promised reductions in aircraft emissions with increases in flight numbers. The arrangement to link passenger growth with the introduction of quieter aircraft was just ignored.
    If we are to have yet more growth in aviation, our government should give them the incentive to ensure that the promised emission reductions are actually delivered by prohibiting growth until the reductions are proven. It’s the only fair way, as abuses of environmental deals cannot be undone.

    1. That’s a good way to do it – lock them into flat or declining emissions first. If you can grow without rising emissions, noise or pollution, fine. Otherwise, work on efficiency first and then expand when it can be done cleanly.

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