Destination: Net Zero – Airport expansion and climate change


Gethin Thomas, barrister at 39 Essex chambers argues that the UK will miss it¹s climate change net zero obligations by 2050 significantly if the UK¹s massive regional airport expansion plans are realised. The views expressed in the blog are that of Gethin Thomas.



There is significant airport expansion planned across England. 21 of the country’s biggest airports intend to add 192 million passengers to the 286 million that already use their terminals over the next 10-20 years, which equates to a growth of 67%.[1] For example, next week a decision is expected on Bristol Airport’s planning application to expand, increasing the number of passengers from 10 to 12 million per year. UK airports are planning to expand almost three times faster than the CCC consider is sustainable.[2]


Climate change: the context

In the judicial review claim of the Secretary of State for Transport’s Airports National Policy Statement (“ANPS”) designating a third runway at Heathrow as the preferred scheme for meeting the need for new airport capacity in southeast England, R. (on the application of Spurrier & ors) v Secretary of State for Transport [2019] EWHC 1070 (Admin) (“the Heathrow JR”),[3] Hickinbottom LJ and Holgate J summarised the mechanics of the climate change crisis in the following terms:

  • the concentration of greenhouse gases (“GHGs”) in the earth’s atmosphere is directly linked to average global temperatures;
  • the concentration of GHGs has been rising steadily – and, with it, mean global temperatures – since the start of the Industrial Revolution and;
  • the most abundant GHG, accounting for at least two-thirds of all GHGs, is carbon dioxide (CO2) which is largely the product of burning fossil fuels.[4]


The Divisional Court recognised that: 

The increase in global temperature has resulted in (amongst other things) sea level change; a decline in glaciers, the Antarctic ice sheet and Arctic sea ice; alterations to various ecosystems; and in some areas a threat to food and water supplies. It is potentially catastrophic.[5] (emphasis added)

It is well documented that the catastrophic effects of climate change are already being felt, and recent research estimates that the number of climate disasters could double in less than 21 years.[6]


Aviation emissions

Direct emissions from aviation account for about 3% of the EU’s total greenhouse gas emissions and more than 2% of global emissions.[7] In addition to aircraft engine pollutants, airport surface access transport movements, as well as airside ground movements and airport operations, further increase the overall GHGs emissions from aviation. Moreover, aircraft exhausts also emit condensation trails, consisting of water vapor, which are also likely to play a role in global warming, by trapping heat radiating from the Earth’s surface.[8]

UK carbon emissions from aviation have almost doubled since 1990.[9] By this year, global international aviation emissions are projected to be around 70% higher than in 2005 and the International Civil Aviation Organization (“ICAO”) forecasts that by 2050 they could grow by a further 300-700%.[10]

UK aviation currently accounts for around 7% of the UK’s total greenhouse gas emissions, but its share of emissions is likely to continue to increase as other sectors, such as energy and manufacturing, decarbonise more quickly. This means that aviation could represent a 25% share of the UK’s greenhouse gas emissions by 2050.[11]

Accordingly, any airport development which would lead to an increase of carbon (and other GHGs) emissions must be rigorously scrutinised. The Airports Commission identified four key areas relevant to the assessment of the carbon impact of airport expansion:

  • increased airport capacity leading to a net change in air travel;
  • airside ground movements and airport operations;
  • changes in non-aviation transport patterns brought about by a scheme’s surface access strategy; and
  • construction of new facilities and surface access infrastructure.[12]


The Net Zero target and aviation emissions

The Paris Agreement, an agreement within the United Nations Framework Convention on Climate Change (“UNFCCC”) was adopted by consensus on 12 December 2015, following the 21st Conference of the Parties of the UNFCCC. The UK ratified the Paris Agreement on 17 November 2016. In the recitals to the Paris Agreement, the parties ‘[recognised] the need for an effective and progressive response to the urgent threat of climate change on the basis of the best available scientific knowledge’.

The Paris Agreement’s key aim is to improve the global response to the threat of climate change by keeping a global temperature rise this century well below 2 degrees Celsius above pre-industrial levels, and moreover, to pursue efforts to limit the temperature increase even further to 1.5 degrees Celsius (as prescribed in Article 2).

Article 4(1) states that ‘in order to achieve the long-term temperature goal set out in Article 2, Parties aim to reach global peaking of greenhouse gas emissions as soon as possible…’. Article 4(2) requires parties to ‘prepare, communicate and maintain successive nationally determined contributions that it intends to achieve.’ Article 4(3) states that each party’s ‘successive nationally determined contribution will represent a progression beyond the Party’s then current nationally determined contribution and reflect its highest possible ambition…’ (emphasis added).

In May 2019, the CCC recommended that, in order to ensure that the UK’s nationally determined contribution reflects ‘its highest possible ambition’, the UK should set a net-zero greenhouse gas emissions target for 2050 (“Net Zero”).[13] Following this advice, the CCA 2008 was amended to make the Net Zero target law on 27 June 2019.[14]

The Government recognised that ‘international aviation and shipping have a crucial role to play in reaching net zero emissions globally’,[15] and has made clear that its plans for net zero emissions cover the whole of the economy, including emissions from international aviation and shipping. The Government has indicated an intention to legislate to that effect.[16]

The CCC had previously recommended carbon budgets be on an appropriate path towards a 2050 target that allows room for international aviation emissions, with the aim of achieving an overall 80% reduction by 2050 (the pre-Net Zero target). In 2015, the CCC concluded that sensible planning assumptions was for international aviation emissions in 2050 to return to their 2005 level. This followed the CCC’s earlier advice in its 2009 report, Meeting the UK aviation target – options for reducing emissions to 2050, that UK aviation emissions should be kept below its 2005 level, which was 37.5MtCO2.[17]

In 2018, the Government acknowledged that it is not likely to be on track to meet this target:

DfT’s October 2017 aviation forecasts give CO2 emissions from UK departing flights of between 36.6 and 45.7Mt in 2030; between 36.3 and 45.1Mt in 2040; and between 35.0 and 44.3Mt in 2050, depending on demand scenario and airport capacity options.[18]

Those DfT UK Aviation Forecasts (dated 24 October 2017) specifically estimated that:

  • The total baseline emissions for the UK would be between 35.0 and 42.1 MtCO2.
  • If the Heathrow North West Runway scheme is implemented, the total UK emissions would be between 38.1 and 44.1 MtCO2.

Accordingly, on the Government’s projections, the 37.5 MtCO2 target may well be breached without airport expansion.

However, and in any event, the 37.5 MtCO2 target was set in order to achieve the then target under section 1 of the CCA 2008: a reduction of emissions by 80% by 2050. It has now been superseded by the implementation of the Net Zero target, and is therefore, logically, out of date. This is likely to be a change of potentially fundamental importance. The 37.5 MtCO2 target has been relied upon, for example, in the planning officers report to North East Somerset Local Planning Authority, in respect of Bristol Airport’s application to expand.[19]

Lord Deben, the Chairman of the CCC, has written to the Secretary of State (dated 24 September 2019), in order to address the implications of the implemented Net Zero target for international aviation emissions. The CCC has advised that demand growth must be limited to 25%.[20] The CCC’s scenarios from its net zero advice suggest that:

aviation emissions could be reduced from 36.5 MtCO2 in 2017 to around 30 MtCO2 in 2050 through a combination of fuel efficiency improvements, limited use of sustainable biofuels, and by managing demand growth. Major technological breakthroughs in commercial aviation are unlikely to make a significant difference to emissions by 2050 given long development and certification lead times, and slow turnover of the fleet.[21]

Moreover, Professor Jim Watson, in the UK Net-Zero Advisory Group to the Committee on Climate Change Chair’s Final Report, has also emphasised the importance of a lower carbon emission target for aviation emissions:

The further ambition scenario includes a reduction in aviation emissions when compared to the previous CCC scenario for meeting the 80% emissions reduction target. This previous scenario includes passenger demand growth of 60% from 2005 levels, which would be offset by improvements in airframe and engine technology and some use of biofuels. Demand has already increased by approximately 30% since 2005, so this means a further 25% growth in demand from current levels. The further ambition scenario includes additional biofuels and the introduction of hybrid electric aircraft in the 2040s…

Whilst the CCC are right to be cautious on the timescale for replacing fossil fuels with biofuels and electrification, some advisory group members felt that the assumptions for the aviation sector do not represent a fair share of the reductions required for net zero. Allowing 31 MtCO₂e of aviation emissions in 2050 stands out if most other sectors are required to reduce emissions to very low levels to achieve net zero. This reinforces a need to support low and zero carbon innovations in the aviation sector, and to explore how demand growth can be limited further so that it is below the CCC’s trajectory. (emphasis added)


The emerging UK Aviation Strategy

The UK’s aviation strategy is currently in development. Insofar as is relevant, the Aviation 2050 Consultation Paper (December 2018),[22] explains that, in order to implement the government’s long term vision and pathway for addressing UK aviation’s impact on climate change, the government also proposes to (at para 3.96):

Require planning applications for capacity growth to provide a full assessment of emissions, drawing on all feasible, cost-effective measures to limit their climate impact, and demonstrating that their project will not have a material impact on the government’s ability to meet its carbon reduction targets

Whilst this is only an emerging draft policy, the Government’s obligation to meet its carbon reduction targets is enshrined in the CCA 2008.


Assessing applications

In my view, there are two main principles that must be inform the assessment of the climate change impacts of any airport’s application for expansion:

  • First, carbon emissions may, in and of itself, be a reason for a refusal of development consent, if it impacts the Government’s ability to meet its carbon reduction targets.
  • Secondly, the climate change impacts of the application cannot be assessed in a vacuum, but must be considered against the planned airport expansions across the UK.

First, the carbon emissions may, in and of itself, be a reason for a refusal of development consent, if it impacts the Government’s ability to meet its carbon reduction targets. The duty under section 1 of the CCA 2008 is overarching. Moreover, the Airports National Policy Statement made clear that:

Expansion must be deliverable within national targets on greenhouse gas emissions…

Any increase in carbon emissions alone is not a reason to refuse development consent, unless the increase in carbon emissions resulting from the project is so significant that it would have a material impact on the ability of Government to meet its carbon reduction targets, including carbon budgets….[23]

As such, it is reasonably arguable that if the increase in carbon emissions resulting from the project would have a material impact on the ability of Government to meet its carbon reduction targets, then that is so significant that development consent may be refused. Expansion cannot be deliverable if it would result in the breach of national targets on GHGs.

Secondly, it is critical that the climate change impacts of the application are assessed against the current planned airport expansions in the UK. The carbon emissions impact of the application on the ability of the Government to meet its national targets has to be assessed with those expansions in mind (particularly Heathrow).

It is notable that the CCC observed that:

The Government should assess its airport capacity strategy in the context of net zero. Specifically, investments will need to be demonstrated to make economic sense in a net-zero world and the transition towards it. Current planned additional airport capacity in London, including the third runway at Heathrow, is likely to leave at most very limited room for growth at non-London airports.[24] (emphasis added)

This conclusion is consistent with the DfT’s aviation forecasts of 2017, referred to be above. Therefore, and as further considered below, this Application may be scrutinised against that context.

It is important to note that, in the Heathrow JR, the Divisional Court made clear that the up to date scientific position in respect to climate change would be re-visited at the Development Consent Order (“DCO”) stage of the Heathrow scheme. Indeed, the opportunity for further scrutiny of the climate change impacts at a the DCO stage was partly why the Divisional Court dismissed the climate change ground in the Heathrow JR.[25] This is of wider relevance to DCO applications for expansion made by other airports.



Given the issues explored above, it is likely not to be possible for all of the planned expansions across the UK to all progress if the Government is to meet Net Zero. Technological advancements to drastically decarbonise aviation are not yet in sight, and so difficult decisions as to limiting individual airport expansion will be necessary, if Net Zero is to be a reachable destination.


[1][2] This article has been derived from submissions drafted in support of Interested Party’s response to a request for comment and further information, to the Development Consent Order application to re-open and expand Manston Airport.

[3] Appeal pending.

[4] At para 559.

[5] At para 559.

[6] Ramon E. Lopez  Vinod Thomas  Pablo A. Troncoso, “Impacts of Carbon Dioxide Emissions on Global Intense Hydrometeorological Disasters”, Climate Disaster and Development Journal, (Volume 4, Issue 1, January 2020) (available online here: (last accessed 30 January 2020)).

[7] European Commission, Reducing Emissions from Aviation: (last accessed 30 January 2020).

[8] Lisa Bock and Ulrike Burkhardt, Institute of Atmospheric Physics in Oberpfaffenhofen, Germany, “Contrail cirrus radiative forcing for future air traffic” Atmos. Chem. Phys., (19, 8163–8174, 2019), available online here: (last accessed 30 January 2020).

[9] Airports Commission: Final Report (dated July 2015), p 66, para Figure 2.12.

[10] European Aviation Safety Agency, Emissions: (last accessed 30 January 2020).

[11] HM Government, Aviation 2050 (December 2018), para 1.24.

[12] Airports Commission, Final Report (dated July 2015).

[13] Committee on Climate Change, Net Zero – The UK’s contribution to stopping global warming (dated 2 May 2019), available online here: (last accessed 30 January 2020).

[14] Climate Change Act 2008 (2050 Target Amendment) Order 2019 SI No 1056, art.2(2) (June 27, 2019).

[15] Climate Change Act 2008 (2050 Target Amendment) Order 2019 SI No 1056, art.2(2) (June 27, 2019), Explanatory Notes, para 10.5.

[16] The Secretary of State for Business, Energy and Industrial Strategy, Mr Greg Clark, stated that ‘We have followed the advice of the Committee on Climate Change and our plans for net zero cover the whole economy, including international aviation and shipping. We await the committee’s advice on how to legislate.’ Hansard HC (12 June 2019) Volume 661 Column 682 Net Zero Emissions Target.

[17] Climate Change Committee, Fifth Carbon Budget Report (dated November 2015), p 53 available online here: (last accessed 30 January 2020); Meeting the UK aviation target – options for reducing emissions to 2050 (dated December 2009), available online here: (last accessed 30 January 2020). In the Government’s Clean Growth Strategy (dated October 2017), it was considered to be possible to meet the 2050 target under the CCA 2008 domestically if aviation emissions are 44 MtCO2. However, this was based on a ‘carbon-traded’ scenario.

[18] Clare Perry (then Minister of State (Business, Energy and Industrial Strategy) (Energy and Clean Growth)), Aviation: Exhaust Emissions: Written question – 120954 (8 January 2018), available online here: (last accessed 30 January 2020).

[19] Application No: 18/P/5118/OUT, Officers’ Report (29 January 2020), available online here: (last access 5 February 2020).

[20] This letter is cited in the DfT’s request for comments and further information, para 22. It is available online here: (last accessed 30 January).

[21] Annex, p 9: (last accessed 30 January).

[22] Cm 9714.

[23] DfT, Airports National Policy Statement (5 June 2018), paras 2.18 and 5.82. Available online here: (last accessed 30 January 2020). It is important to note that the DfT’s modelling was based on the expansion plans set out in the 2003 Air Transport White Paper.

[24] Annex, p 14: (last accessed 30 January).

[25] See para 648 of the Divisional Court’s judgment.