UK airport expansion plans mean higher aviation emissions – making a mockery of “net zero” targets

The carbon emissions from UK aviation according to the Climate Change Committee (CCC), were 39.3 MtCO2 in 2018. They were a little higher in 2019, making up 8% of total UK emissions. The CCC advised the government that for its Sixth Carbon Budget (2033 – 37) the carbon emissions of the UK should fall by 63% from their 2019 level. And “net zero” by 2050.  The CCC has advised the government that there should be “no net airport expansion”. But the government has ignored this advice, and recently government inspectors have allowed expansion plans at Stansted and Bristol.  Southampton and Leeds Bradford airports are trying to get expansion approval. So instead of making every effort to cut UK aviation emissions, things are going in the opposite direction. Stansted Airport Watch says that, taken together, the airport expansion proposals that have been approved in the past year, and those in the pipeline, will increase UK airport capacity to over 500 million passengers per annum. This compares to 297 million passengers in 2019, before Covid, and 292 million in 2018.  [ link ] “With so much extra airport capacity in the pipeline, there will be no prospect of aviation achieving the Government’s objective of net zero emissions by 2050.”  




PRESS RELEASE (Stansted Airport Watch) 

28 February 2022 

Aircraft emissions are amongst the fastest growing causes of global warming and yet the Government continues to support airport expansion projects all across the UK.

It is now clear that the approval of the Stansted Airport Planning application last year has set a dangerous precedent.  Airports all across the UK are now jumping on the bandwagon.

In the past 12 months, Bristol, Southampton and Leeds Bradford airports have all received the go-ahead for major expansion.  In addition, Heathrow, Gatwick and Luton airports are all now bringing forward expansion proposals – each of which would increase their capacity by 50% [Note 1].

All these projects have Government support – flying in the face of its so called ‘net zero’ policy for aircraft emissions.  Despite the obvious contradiction, the courts have shown a marked reluctance to intervene.

Taken together, the airport expansion proposals that have been approved in the past year, and those in the pipeline, will increase UK airport capacity to over 500 million passengers per annum.

This compares to 297 million passengers handled in 2019, before the Covid pandemic.

In December 2020, the Climate Change Committee recommended that there should be a total freeze on UK airport expansion until such time as the aviation industry could demonstrate that it was on track to achieve net zero emissions by 2050.  However, the Government has decided to completely ignore this advice from its own independent experts.

Covid has dramatically reduced the demand for air travel in the past two years, but airlines expect a return to business as usual by 2024 or 2025 at the latest.  If that is the case, and with so much extra airport capacity in the pipeline, there will be no prospect of aviation achieving the Government’s objective of net zero emissions by 2050.  Instead, aviation could well be the largest single contributor to UK greenhouse gas emissions. [Note 2]

Stansted Airport Watch Climate Change Adviser Mike Young, commented: “It’s as if the Government is living in a parallel universe.  We can expand UK air travel to 500 million passengers a year or we can make a serious attempt to tackle climate change.  However, we cannot do both.”



  1. Details of the expansion plans for individual UK airports are available from the SAW Campaign Office upon request.
  2. See House of Commons Research Briefing “Aviation, decarbonisation and climate change”, September 2021, at


The Climate Change Committee said, in 2020, that:

“The Committee is advising that the UK set its Sixth Carbon Budget (i.e. the legal limit for UK net emissions of greenhouse gases over the years 2033-37) to require a reduction in UK emissions of 78% by 2035 relative to 1990, a 63% reduction from 2019. This will be a world-leading commitment, placing the UK decisively on the path to Net Zero by 2050 at the latest, with a trajectory that is consistent with the Paris Agreement.”

“Based on the most recent official UK emissions data, total UK aviation emissions increased by 0.8% from 2017 levels to 39.3 MtCO2e/year in 2018. Within this, emissions from international flights increased by 1.1% to 36.7 MtCO2e/year, emissions from domestic flights fell by 5.9% to 1.5 MtCO2e/year, and emissions from military aviation fell 0.6% to 1.1 MtCO2e/year. Aviation therefore comprised 7% of UK GHG emissions in 2018, and within this international aviation dominates at 93% of UK aviation emissions (Figure M8.1).

“To be consistent with other sectors and the Climate Change Act framework, these GHG emissions do not include non-CO2 impacts of aviation…”


The CCC sets out four scenarios for what happens to UK aviation emissions in the next decades.

They say:

b) Alternative pathways for aviation emissions Each of our exploratory scenarios for aviation sees emissions fall from 2018 to 2050 by more than 35% (Figure A3.7.b), though with different contributions from efficiency improvements, sustainable fuels and constraints on demand (Table A3.7):

• Headwinds assumes the same 25% growth in demand from 2018 to 2050 as in the Balanced Pathway, although with higher demand in the 2030s due to a net increase in airport capacity. Improvements in efficiency are as in the Balanced Pathway, while biofuels comprise 20% of the fuel mix by 2050. Emissions are 25 MtCO2e in 2050, 36% below 2018 levels.

• Widespread Engagement has lower demand, with an overall reduction of 15% on 2018 levels and therefore around half the 2050 demand as in the baseline. This is in line with the Climate Assembly UK’s ‘flying less’ scenario. It includes a substantial reduction in business aviation due to widespread near-term adoption of videoconferencing. Efficiency improvements are slightly faster than those in the Balanced Pathway at 1.6% per annum, while the share of biofuels in 2050 is slightly lower at 20%, with a further 5% contribution from the biogenic fraction of waste-based fuels.2 Emissions in 2050 are 15 MtCO2e, 62% below 2018 levels.

• Widespread Innovation has a greater contribution from technological performance, both in terms of improved efficiency (2.1% per annum) and the contribution of sustainable aviation fuels. By 2050, around a quarter of fuel use is biofuel, with a further quarter carbon-neutral synthetic jet fuel. These technical improvements lead to a lower carbon-intensity and lower cost of aviation, although demand in this scenario is considerably higher, reaching 50% above 2018 levels by 2050 (in line with the Climate Assembly UK’s ‘technological change’ scenario). Emissions in 2050 are 15 MtCO2e, 63% below 2018 levels.

• In Tailwinds, the reductions in demand under Widespread Engagement are combined with the technology improvements in Widespread Innovation. Demand in 2050 is 15% below 2018 levels and efficiency improves at 2.1% per annum. Very similar volumes of sustainable fuels are used as in Widespread Innovation, but when applied to the lower fuel consumption in Tailwinds these comprise a higher combined share of 95% of fuel use. Emissions in 2050 are 1 MtCO2e, 97% below 2018 levels.

In each case, for the aviation sector to reach Net Zero by 2050, the remaining emissions will need to be offset with greenhouse gas removals (see section 11). In addition to the GHG emissions presented here, aviation also has non-CO2 warming impacts due to contrails, NOx emissions and other factors.

While outside of the emissions accounting framework used by UK carbon budgets (see Chapter 10), we estimate the additional warming from these non-CO2 effects in section 4 of Chapter 8.”



Climate Change Committee data for 2019

“Aviation (8% of 2019 emissions). A policy framework is needed to achieve net-zero emissions by 2050, including demand-side measures, efficiency and low-carbon fuels, with residual emissions offset by verifiable removals. The UK’s airport capacity strategy should be reviewed in light of the net-zero target. Action is also needed on non-CO₂ warming effects from aviation.”
There was an earlier figure of 6.3% of British CO2 emissions arising from aviation in 2005.  That was from a government minister in the House of Commons in 2007.
Those numbers are for the CO2 alone, and do not include the non-CO2 impacts of the aircraft emissions at high altitude. Those include various gases, and water vapour, which forms contrails that then (if the air is moist) start the formation of cirrus cloud.
The number also only counts the emissions of outbound flights, not  those returning. The convention is to attribute the carbon of a flight to country from which it departed.  But as most flights at UK airports are taken by Brits, and perhaps 70% or more are leisure, (so people have a return flight back to the UK) it might be more accurate to count the carbon from both halves of the journey.
That would put the figure for UK aviation carbon even higher than the 8% stated by the CCC for 2019.


UK government (ONS) data on greenhouse gas emissions

“The data for greenhouse gas emissions (GHG) In the UK is provided up to the year 2019, before the coronavirus (COVID-19) pandemic. The total GHG emissions for 2019 were over 550 million tonnes of carbon dioxide equivalent (Mt Co2e) (residence basis). This is a decrease of approximately 3% on the previous year’s emissions, continuing the general downward trend of greenhouse gas emissions in the UK since 1990.”,Co2e)%20(residence%20basis).