Davies fails to make the case for a 3rd runway

Posted by Graham Thompson — 1 July 2015 at 2:17pm - Comments
Greenpeace activists climb onto the top of a plane at London Heathrow Airport
All rights reserved. Credit: Nick Cobbing / Greenpeace
Greenpeace activists climb onto the top of a plane at London Heathrow Airport

This morning the Davies Commission reported back on airport expansion in the South East of England. To the surprise of absolutely no-one, Davies recommends a third runway at Heathrow, and then tries to make a case that this can be delivered within the UK’s legally binding carbon budget. Inevitably that case is riddled with holes you could fly an airbus through, which, in a way, is the job it was intended to do.

The runway is ‘needed’ in order to accommodate the growth in frequent leisure fliers - the top 15% of UK fliers who take 70% of our flights. Business flights have dropped by 36% in the last decade, and 52% of Britons didn’t fly last year. In 2003, only 1% of the world had ever flown[1].  As an industry that primarily benefits the 1% aviation is given huge tax breaks and other advantages by the government. One of these is its carbon budget. Whilst the UK economy as a whole is required to cut our carbon emissions by 80% from 1990 levels, aviation is allowed to increase theirs by 120%.

Aviation had already filled that huge allowance ten years ago, and so demonstrating that a new runway at Heathrow can be built within an exhausted and exceeded carbon budget was always going to be challenging. To say the least.

Davies has produced a long and complicated report which includes a lot of varied and in some cases ‘innovative’ economic modelling, so it’ll take a while to untangle and find all the devils hiding in the details. And that needs to be done, and it needs to be done rigorously so that we can have an informed debate about the real risks and consequences of a third runway at Heathrow.

Perhaps the key figure in the report is the 22.2 million extra tonnes of CO2 emissions expected from expansion. That’s a lot, but it may be a big underestimate if some of Davies assumptions turn out to be as unrealistic as they appear.

For example, one of the demand restriction measures suggested by Davies, necessary to keep aviation emissions in line with the climate change act and our carbon budget, is an ETS carbon price of £330 per tonne. The current carbon price is about £5.30 a tonne, and rather than starting out on the extremely steep rise needed to increase by 6,200%, it’s been dropping.

Another option is for passenger jets to become more efficient. But as the Royal Society concluded in their report on aviation engineering’s capacity to reduce emissions:

“Many of the operational opportunities, like increasing the proportion of seats occupied, are close to their limits, particularly for the low-cost airlines, which have placed the elimination of operational inefficiencies at the core of their business model. If aviation is to achieve significant emission reductions, it will require innovative and ambitious engineering.”

Furthermore, should this innovative and ambitious engineering ever appear, it may well be too late. As the Royal Society noted, “the aircraft development process is slow and the service life is long.”

And then there are biofuels, which are a whole other can of worms. The arguments surrounding their potential are numerous, but they’re certainly not a magic bullet ready in the chamber – when Richard Branson flew a Virgin jet on a one-way short haul flight from London to Amsterdam, in what was billed as the first biofuelled passenger jet flight, he needed 150,000 coconuts to provide less than 5% of the fuel.

These examples are indicative of the problems in the report – it has a tendency to assume that all sorts of wonderful and unexpected things will happen, and relies on this procession of political implausibilities to make the third runway plausible. It’s really only one step away from saying ‘so long as someone solves all the problems, there’ll be no problems’.


1. Organizational and growth trends in air transport. In Towards sustainable aviation Upham P, Maughan J, Raper D.W, Thomas C 2003pp. 19–35. Eds. London, UK:Earthscan.

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