Written evidence submitted by Possible (HEN0015)

Possible is a UK based climate charity working towards a zero carbon society, built by and for the people of the UK.

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About Possible

1. Possible is a climate action charity working for a zero-carbon society built by and for the people of the UK. Our projects and campaigns prioritise public involvement and positive social and economic impact, as well as cutting emissions across energy, heat, travel and consumption. Our work on transport includes our campaign for a frequent flyer levy (a progressive tax which increases per flight each person takes in a given time period), exploring how to increase the UK’s international rail capacity, and the Sustainable Travel Leave scheme, which supports employers to offer their staff additional days of paid leave to travel without flying.[1]

Summary of Possible’s position on the draft HENPS and the proposed new runway

2. We are really concerned that the government is attempting to push forwards with the proposed expansion of Heathrow airport, including the new runway. It is our understanding that the climate, air and noise pollution impacts are impossible to sufficiently mitigate, and will cause serious - and expensive - harms to the UK. It is also now clear that the economic case does not exist. The government’s own analysis shows that any claimed economic benefits will not be net economic gains, but will only be a transfer of economic activity from the broader UK to London and the South East. Most seriously of all, the government’s analysis finds that the total economic impact of the third runway will be negative, costing between £23bn and £62bn due to the harms it will cause. On this evidence, we do not believe that any rational government, mindful of its obligations to support the UK’s economy and meet its climate commitments, could decide in favour of the third runway.

3. We are grateful for the Committee’s in-depth consideration of the HENPS, and hope that the Committee will adopt a robust position and urge the government not to proceed with this damaging scheme, which would deal a devastating blow to both the UK’s climate commitments and to our economy, as well as causing serious harms to the local area and Londoners’ health. 

Responses to questions

a. The extent to which the draft HENPS provides clear and coherent guidance to the Secretary of State about how to assess a proposed scheme.

4. We are concerned that the draft HENPS contains some omissions and incomplete information, as well as some misleading claims. This will make it more difficult for the Secretary of State to make an evidence-based decision regarding the UK’s economy and our climate change commitments. Our concerns relate to the provision of information about the climate impacts and economic impact of aviation.

5. Overall, the discussion on the economic benefits of aviation does not provide a full picture, and skews heavily towards the positives without including information on the negative overall economic impacts of aviation growth in the UK. For example, section 2.23 claims that “Without expansion, passengers are likely to suffer from higher fares and more delays.” This ignores the serious concerns which have been raised on the likelihood that the expansion will increase costs for passengers, who will have to pay for the costs of the third runway via higher landing charges. UK airlines have warned that this could add £250 to the cost of a family’s fare. Also not mentioned is the UK’s increasingly large tourism spend deficit of more than £40bn; much more tourism spend leaves the UK than enters it via incoming visitors. Our report with the New Economics Foundation makes it clear that previous increases in airport capacity have only worsened this trend.  In addition, business flights have flatlined for decades despite growth in flights.

6. The finding from the government’s own analysis released with the HENPS that, far from supporting the UK’s economy or driving growth, the third runway would cause net harms costing up to £62bn should in itself be enough to make any Secretary of State refuse permission. However, it is not helpful that vital elements of the overall economic impact of the UK aviation industry have been excluded from the HENPS, and therefore have been excluded from the matters the Secretary of State must consider when making their decision.

7. On climate, there are several areas of omission. Aviation is an extremely high-carbon sector, and the new runway would produce an additional 4.4 million tonnes of emissions per year. The Jet Zero Strategy (JZS) sets out the government’s goal of greatly increasing aviation capacity, while at the same time drastically reducing carbon emissions over the next two decades to align with net zero. This strategy relies on as yet undeveloped and largely undelivered technological solutions, which the government hopes will make low-carbon flying possible. We have a number of serious concerns about these technological solutions. The Sustainable Aviation Fuel (SAF) mandate, despite its current small size, is already failing to be delivered, and there is an ongoing lobbying effort to weaken its standards and allow environmentally harmful biofuels from food crops to be included.

8. Due to the lack of technological solutions for low-carbon or zero-emissions flight, the pathways to balance aviation emissions also rely on increasingly large amounts of negative emissions (also known as Carbon Dioxide Removal). These exist as yet only on a very small scale, as it is difficult, resource-intensive and expensive to remove carbon from the air and store it underground. There is no delivery mechanism for achieving the tens of millions of tonnes of carbon removals each year by 2050 that is envisaged in the JZS, nor has there been any consideration of how this would be paid for. If the cost of removing carbon produced by flights is levied on the cost of those flights, as appears to be the only option, then this alone would cause a decrease in demand levels which would leave the third runway an unusable stranded asset. In addition, our report with Chatham House found that even if technological solutions do deliver, significant demand management will still be required within the short to medium term to keep aviation emissions within carbon budgets. The Climate Change Committee has also been clear that there is no room for net overall aviation expansion until technological solutions have been deployed on an unprecedented scale.

9. It is therefore really worrying that the HENPS does not require the Secretary of State to consider whether the projections in the Jet Zero Strategy for very rapid technological development are actually being met, or will be delivered at the speed and scale required to mitigate the huge increase in emissions that the third runway would bring. If the aviation industry cannot deliver on the technological change it has promised to address its emissions, it should not be permitted to expand its operations until it has done so.

10. It is therefore positive that Section 5.77 sets out that:

“Given the challenge of reducing aviation emissions, it is also required that any promoter of expansion will put forward a comprehensive package of mitigation measures, which builds on Heathrow’s current decarbonisation commitments.

The Secretary of State, when considering any application for development

consent, would expect to see evidence and consideration of measures

including, but not limited to:

• Significant and sustained investment in engineered greenhouse gas removals, such as Direct Air Carbon Capture and Storage (DACCS) and Bioenergy with Carbon Capture and Storage (BECCS).”

11. However, the HENPS fails to properly address the non-CO2 emissions which make up two-thirds of aviation’s warming impact, or to place appropriate requirements on the Secretary of State to consider this. Section 5.67 claims that “academic research shows that there continues to be significant uncertainty regarding the magnitude of aviation’s non-CO2 impacts on the climate”, and therefore “ the applicant is not required to quantify the non-CO2 impacts of any scheme but should assess these impacts qualitatively”. We think this is really misleading; there is a broad scientific consensus (since at least 2021) that the non-CO2 impacts account for about two-thirds of aviation’s warming impacts. The non-CO2 impacts of the third runway should therefore be required to be quantitatively assessed, and the scheme proposer should have to explain how these will be addressed.

12. We would urge the Secretary of State to ensure that for any plan to be approved, the promoter of expansion must propose a package of mitigation measures which (a) addresses the full scale of emissions resulting from use of the third runway, without relying on offsets (long discredited as junk credits which provide little if any actual emissions reductions); (b) includes full mitigation of non-CO2 emissions; (c) is fully costed and does not rely on taxpayer subsidies; and (d) looks at the impact on demand of passengers who use the third runway being required to pay the full cost of mitigation of those additional emissions. The onus must be on the aviation industry to demonstrate that removals are possible, and show how investment in this speculative and extremely expensive technology will come from the industry causing the emissions, not the taxpayer.

b. The robustness of the Government's evidence and rationale for the need for a third runway at Heathrow Airport.

13. We are not convinced that the government has made a convincing case for the need for a third runway. The government’s argument that the third runway is needed rests on the claims that there will be an increase in demand over time, and that the “whole London airports system is forecast to be full by the mid to late 2040s”; that capacity constraints are creating a risk of flight delays or higher fares; “declining domestic connectivity”; “constraining the scope of the aviation sector to deliver wider economic benefits”; and that the expansion is needed for business travel.

14. We don’t think that any of these claims stand up to scrutiny. The assumption that there will be an increase in demand over time is overly simplistic, and fails to take into account that a perpetual increase in demand for highly carbon-intensive services, for which decarbonisation is very difficult and expensive, is simply not compatible with achieving the UK’s climate targets. In 2026, the UK is already experiencing unprecedented and dangerous heatwaves, while also struggling to meet its carbon budget targets, with the Climate Change Committee warning that “The UK Government is not moving fast enough to reduce greenhouse gas (GHG) emissions and to protect households and businesses from volatile fossil fuel prices”. In 20 years’ time in the late 2040s, the UK’s net carbon budget will be very close to zero. By that point we will be experiencing significantly worse climate impacts. If the government is serious about technological solutions such as carbon removals, then the associated costs will drive down demand.

15. Domestic flights are an unnecessary waste of scarce remaining emissions budgets, given the multiple low-carbon alternatives available for these shorter journeys. The government should encourage rail and coach operators to fill this gap, not attempt to increase these short flights for which much lower-emissions alternatives are available. We think that the higher fares argument is invalidated by the clear evidence that if the expansion goes ahead, passengers will face much higher charges in order to recoup the enormous capex costs of the third runway. Business travel has failed to grow through the previous two decades of airport expansion. The “wider economic benefits” claim is comprehensively disproved by the government’s own analysis, which finds that the third runway’s overall economic impact will be to cost the UK’s economy tens of billions.

16. We are confused by the lack of consistency in the government’s position on the vital question of whether or not the third runway will bring economic benefits. It seems to us that given that the analysis itself is very clear that the third runway will cause net harm to the UK’s economy, it would be unacceptable and irrational for the Secretary of State to approve the HENPS on the basis of “wider benefits” which have been shown to be non-existent.

c. Whether it is appropriate for Heathrow expansion to be designated as Critical National Growth Infrastructure.

17. We think this is really inappropriate. Our concern is that this designation would lead to a “policy presumption in favour”, and would make it more difficult to ensure democratic accountability and evidence-based decision making.. It is really concerning that the case for the third runway to be designated as CNGI rests on the argument that it would “help achieve our economic growth objectives”, when the government’s own analysis demonstrates that this is not true and the third runway would be economically harmful, and that any economic growth would be relocated from the regions to the South East, rather than being net or additional. It would be irrational and a worrying abuse of process for the government to produce economic analysis finding that the third runway would cost the UK up to £62bn, and then force it through via designating it as CNGI and thereby removing the requirement for the project to provide net economic benefits.

d. How effectively and robustly the draft HENPS sets out the assumptions and requirements of the Government’s ‘four tests’ for expansion, on:

Economic growth across the country.

Air quality.

Noise.

Climate change mitigation.

18. On economic growth, the framework sets out some useful criteria, including that any expansion must provide tangible economic growth across the UK and at national, regional and local level. It could be made clearer that all of these types of growth must be net or additional, i.e. it should not be permitted just to relocate growth into the South East from other regions. It would also be useful to clarify how different numbers in the Department for Transport’s analysis relate to each other; the scheme is claimed to provide “between £29.2 billion to £42.4 billion of cumulative benefits to UK passengers and the wider economy by 2060”, but it is also made clear that the Department’s calculation of the net present value, i.e. the overall social value across all costs and benefits, is a negative of between £23.4 billion and £62.5 billion. It therefore seems to us that the use of the cumulative benefits figure by the Department for Transport is misleading, because actually these are outweighed by the costs that would result from the third runway.

19. In addition, the economic test should also assess the potential for passenger cost increases resulting from the need to fund the construction cost of the third runway, as well as to fund the associated infrastructure such as increased public transport capacity. The taxpayer must not be held liable for these costs. It should also assess the cost of mitigation of all the emissions, both CO2 and non-CO2, from the third runway, and how the airport proposes these costs will be covered. Again, it would be grossly unfair for UK taxpayers to end up being hit by these costs, while the airport’s shareholders (largely overseas-owned investment organisations, including the state investment funds of Qatar and the China Investment Corporation) rake in the profits.

20. On air quality, a third runway would mean around 276,000 extra flights every year. It is hard to see how this could be done without substantial increases in harmful pollution, including nitrogen oxides (NOx) and fine particulate matter (PM2.5), and the government’s own analysis has warned that the third runway is likely to harm the health of local people. Ultra-fine particles have still not been properly assessed. Our key concern is that the UK has refused to adopt standards set by the World Health Organisation (WHO) regarding dangerous pollutants and microparticles, and is instead permitting much higher levels. This leaves communities in London and the surrounding areas breathing air which the WHO considers unacceptably dirty and a serious risk to health.

21. London already has the world’s worst air pollution from flights. As well as the harm caused to impacted children, adults and communities, our already over-stretched NHS will have to pick up the bill for this air pollution. We also note that it is not joined-up policy making for the London government to introduce sensible policies such as the ULEZ to reduce dangerous air pollution from cars, while the national government encourages a huge increase in air pollution from flights via airport expansions. No case has been made that technological developments will be sufficient to mitigate this, and we believe that to be impossible.

22. On how the HENPS requires the Secretary of State to consider noise pollution, the consultation does not provide enough information about where aircraft would actually fly and what damage this could potentially do to those who live underneath or near flight paths. Our understanding is that the noise modelling is based on flight path assumptions that are now out of date. These should be updated before any decision is made on this test. Millions more people could be exposed to aircraft noise at levels known to damage health, wellbeing and quality of life. We have already seen significant impacts from the existing flight paths around Heathrow, and the proposed expansion would only exacerbate the problem. Given the lack of an economic case for expansion, we do not see a reason for the government to agree to incur the harms and costs associated with increased noise and air pollution from more flights overhead.

23. We are particularly concerned about the impacts of the proposed third runway on the UK’s emissions and ability to meet our vital climate targets. The proposed climate change mitigation test in the draft HENPS relies heavily on the assumption that there will be unprecedented development and deployment of very nascent, undeveloped, expensive and resource intensive technologies, as set out in the Jet Zero Strategy. The government and the aviation industry are already struggling to scale these technologies to anything like the size required, and aviation industry actors are already lobbying for existing standards to be watered down.

24. The government’s claim that academic research shows that the magnitude of non-CO2 emissions from aviation is uncertain is misleading. The non-CO2 impacts of aviation are widely understood to be around two-thirds of the total, and any uncertainty should result in more caution on allowing expansions to go ahead. It is a serious failing that the HENPS does not require the applicant to quantitatively assess the non-CO2 effects or produce a fully costed mitigation plan, which addresses the full emissions from the third runway under different rates of technological deployment success.

e. How adequate the information published alongside the draft HENPS is, including its accuracy, comprehensiveness and methodology, and how effectively evidence and data have been reflected in the draft HENPS, including on cumulative impacts.

f. How robust are the methodology and data used for any forecasts or assumptions about the future underlying the analysis presented in support of the HENPS, and whether the range and use of scenarios in the document are appropriate.

25. Unfortunately we have not had time to assess this in detail, but we would urge the Committee to push the government to ensure that any assessments are carried out by reliable, independent sources, and do not solely rely on analysis, assessments or findings which have been produced by the airport, the organisations which are proposing the expansion or would benefit from it, or their contractors. We also think it’s inappropriate for the government to simply assume that demand will constantly increase, and to allow capacity to expand on that basis, regardless of the adverse economic, climate and health impacts. Instead, the government should assess scope to reduce excessive demand for flights, including measures such as a frequent flyer levy and scaling alternative, low-carbon transport options such as international rail.

g. How comprehensive and realistic the requirements are in terms of environmental mitigation, supporting measures for communities who will be affected by expansion, and surface access to the airport.

26. We do not believe that it is possible to effectively mitigate the harms to the climate and nature that will be caused by the new runway. The package of mitigation measures set out in section 5.77 does not address non-CO2 impacts, which means it leaves two-third of the climate impacts unmitigated. In addition, there is no requirement within the HENPS for the promoter of expansion to ensure that the mitigation measures are appropriate to the scale of the additional emissions caused. “Supporting” is a vague target, and measures such as SAF have been comprehensively critiqued for failing to provide the emissions reductions promised, and for creating other environmental harms elsewhere, such as deforestation.

27. On the mitigation measures for communities, we do not believe that it is possible to mitigate the serious harms caused by the loss of homes and communities, which will be destroyed to make space for the third runway, along with the serious increases in noise and air pollution which harm health.

28. On surface access to the airport, the HENPS should be strengthened to ensure that the expansion promoter must ensure that car traffic to the airport decreases, that adequate public transport is in place and that public funds are not used for this.

29. Given the high difficulty, uncertainty and cost of mitigating these serious problems, which will cause a lot of harm if not addressed, and the lack of an economic case in favour of the expansion, our view is that it simply does not make sense to allow the airport expansion to proceed.

i. How well the draft HENPS reflects Government policy on airports and aviation, and on other elements of broader a) transport, b) planning and c) climate and environment policy.

30. The draft HENPS is incompatible with climate and environment policy. There is no plan to effectively mitigate the additional 4.4 million tonnes of emissions it will produce each year, and it will make it significantly harder, or even impossible, for the UK to meet its successive carbon budgets or the net zero by 2050 goal. It also does not represent rational economic policy making, given the government’s own analysis that any benefits would be outweighed by costs, and the overall economic impact would be negative by tens of billions of pounds.

j. To what extent the draft HENPS adequately takes into account changes in the context of airport expansion since 2018, such as, for example, current and future capacity at other airports, new legislative requirements, and developments in technology.

31. The draft HENPS does not adequately take into account the climate and air pollution impacts of the cumulative emissions from all the airports which are currently trying to expand. It also does not give sufficient weight to the aviation industry’s track record of failure to deliver on its promises to address emissions using technology.  

k. Whether the draft reflects lessons learned from legal challenges to the 2018 Airports NPS.

32. Unfortunately, it seems that a key learning for the government has been that legal challenges to airport expansions, which are a key pathway to democratic accountability and good decision making, can be avoided by the critical infrastructure designation, which makes decisions ineligible for judicial review. We are really concerned that this is an attempt to avoid challenge over what would be a deeply flawed, dangerous and counter-productive decision to allow Heathrow airport to expand.

l. The effectiveness of the Government's consultation on the draft HENPS.

33. Overall, we do not believe that the third runway could be built and used without locking in a huge amount of harm to our climate and our economy, as well as to the NHS and local communities. Anything the Committee could do to strengthen the requirements which a scheme must meet in order to receive permission would be very welcome. However, given the clear evidence that the airport expansion would be net negative for our economy, it does not seem like rational policy-making to allow this process to continue. We suggest that the incoming new government presents an opportunity to reset policy on airport expansions. If, as the evidence now makes very clear, a new runway would be harmful on every important metric, including being a net negative to the UK’s economy, then there is no point in wasting further time and energy on allowing this process to continue.

July 2026

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