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Climate crisis: Why the carbon numbers mean new airports do not add up

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Michael Pawlyn and Steve Tompkins attempt to debunk the most common defences used by architects to justify working on airport projects

Tompkins and pawlyn

Tompkins and pawlyn

Steve Tompkins and Michael Pawlyn

The late David MacKay [the government’s former chief scientific adviser] argued that sustainability was about ‘numbers, not adjectives’ and that – to paraphrase slightly – ‘if we’re planning for the future of humanity, we’d better have a plan with numbers that add up’.

Nowhere is this advice more relevant than in the heated debate among design professionals about ‘sustainable new airports’.

Various positions have been adopted to justify a continuing role in airport expansion over the coming crucial decade of decarbonisation. So, assuming that the science of climate change as reported in the 2018 IPCC report is accepted, it’s worth examining some of these through a David MacKay ‘numbers’ lens.

Position 1: ’Soon we will have electric planes so we need to be designing ”green-plane-ready airports”’

It is true that the first electric planes are in development, so the question is ‘Can we make the transition in time?’ Currently the energy density of batteries is about 2.6 per cent that of kerosene. This means that to replace one tonne of kerosene would require 38 tonnes of batteries, which is clearly self-defeating for a form of transport that depends on lightness for efficiency.

Battery performance will improve of course but we have to be realistic about how much and over what timeframe. The current predictions are that, 10 years from now we will only have a very limited number of small electric planes capable of short flights.

Coupled with the amount of time it takes to replace plane fleets, it is doubtful whether electric planes will make any significant contribution to greening air travel in the next 20 years. We have half that time to make dramatic cuts in greenhouse gas emissions.

Position 2: ’Biofuels will solve the problem’

There have been promises about biofuels for over 20 years and the delivery has repeatedly fallen short. Biofuels still provide only a fraction of 1 per cent of aviation’s needs.

More importantly, nearly all biofuels compete for land with food production or land that, in the bigger picture, would deliver much greater benefits through being reforested. It can reasonably be argued that shifting all aviation to run on biofuels will create more problems than it solves.

Position 3: ’We can expand air travel within our carbon budget’

The UK Government has set a target of getting to zero carbon by 2050 and the carbon budgets related to this target allow for a degree of growth in air travel. So what’s the problem? The problem of course is that the 2050 goal is nowhere near consistent with what the IPCC has set out as a target of no more than 1.5oC of global heating. This requires an unprecedented 18 per cent year-on-year reduction in greenhouse gas emissions, so to think we can stay within 1.5oC while expanding air travel looks like a dangerous delusion.

Position 4: ’UK business needs expanded airport capacity to remain competitive’

The government’s own data shows that business air travel has not grown in the past 10 years. In fact, it has dropped slightly as people have got more accustomed to video-conferencing. In the UK 70 per cent of all flights are taken by just 15 per cent of all citizens so it is clear that a frequent flyer levy could be highly effective at reducing air travel without unduly impacting either on business or on poorer members of society.

Carbon offsetting is a controversial subject, but a mandatory $100 per tonne charge on flying (as recommended by the UN) would more closely reflect the real offset cost and further incentivise digital alternatives.

Position 5: ’Green airports – low-energy buildings with good public transport links –- will solve it’

Currently Heathrow Airport’s annual CO2 footprint divided by the number of passengers works out to be very close to 5kg of CO2 per passenger trip. Let’s imagine a super-green airport were designed to use 40 per cent less energy than Heathrow: that would be a saving of 2kg of CO2. Let’s say, instead of driving 50km in an average car (with emissions of 200g CO2/km), everyone takes the train instead: that would save about another 6kg of CO2.

So the combined saving of a super-green airport with a passenger arriving by train would be 8kg of CO2. But an economy class return trip to New York emits roughly 1,670kg of CO2 per passenger. In other words, the flying part of the trip currently produces 200 times more greenhouse gas than the savings from the super-green airport and public transport. So, while it is reasonable for architects to argue that greening existing airports is just another component of retrofitting our existing building stock, it has to be admitted that building new or expanding our airports to support greater flying capacity is just contributing to the problem.

Position 6: ’If we don’t design new airports someone else will’

Possibly so, but the same argument is often put forward for all manner of dubious activities, such as selling arms to repressive regimes. Obviously it’s hard to contemplate losing a valuable source of income (think Australia and coal), but the key point here is that this is not leadership; to coin a phrase, it’s trailership – trailing edge thinking that makes our current situation worse and does nothing to advance ethical standards. If an architect argues (with some justification) that unilateral action may not make much difference, then the more effective approach is to engage in collective action.

A headline such as ‘Top UK airport architects and engineers agree moratorium on designing new airports over the next decade’ really would start to change the global attitude towards the climate emergency.

Position 7: ’People who oppose airports are hypocrites if they fly at all’

This accusation is rarely heard from architects who design airports – we’re very polite to each other – but it is common in the media and in politics. The fault with the hypocrisy argument is the implication that unless someone is perfect, they don’t have a right to talk about how things could be better. The fact is that we have all contributed to the climate crisis and, somehow, we all need to work our way out of it. Adopting defensive positions in response to legitimate, constructive criticism is going to make that more difficult.

So, what should architects and engineers conclude from this? In the crucial 10 years we have left to get on top of the crisis, electric planes will not save us. Neither will biofuels. We cannot expand air travel if we are serious about trying to stay within the ‘safe’ 1.5°C limit of global heating. Making airport buildings and ground transportation greener addresses less than 1 per cent of the problem.

There is no robust business case for expanding UK air travel. Calling people hypocrites solves nothing. Science-based evidence points irrefutably to the collapse of our ecosystems and societies within 20 years if we don’t drastically reduce our greenhouse gas emissions. Still think it’s okay to expand air travel? Maybe you’re not a numbers person.

Michael Pawlyn is an architect, speaker and writer. He is the founding director of Exploration Architecture and a member of the steering group for Architects Declare.

Steve Tompkins is a founding director of Haworth Tompkins architects and a member of the steering group for Architects Declare.

This article is written in their personal capacities.

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