The Government cannot expand Heathrow Airport under its current climate policies while remaining on a credible path to the UK's legally binding carbon targets, the independent Climate Change Committee has warned.
In advice published on 16 September at the request of the Department for Transport, the Climate Change Committee said ministers would need to introduce tougher policies requiring the aviation industry to fully address its emissions by 2050 if Heathrow expansion is to proceed consistently with the UK's carbon budgets and Net Zero target.
The committee said there is currently “no credible pathway” for expansion within the UK's climate commitments under existing policies.
CCC says aviation must take responsibility for all emissions
The Climate Change Committee said the Government should legislate to require aviation to address all of its emissions by 2050, either by cutting them directly or by purchasing permanent engineered carbon removals.
It described such a requirement as the only way the proposed Heathrow expansion could be considered consistent with the UK's carbon budgets and its legally binding 2050 Net Zero target.
The advice does not say that a third runway must be abandoned. Instead, it sets out conditions the committee believes would have to be met before expansion could be reconciled with the UK's climate obligations.
Aviation emissions have more than doubled since 1990
The committee warned that aviation has fallen significantly behind the rest of the economy in reducing emissions.
According to its analysis, UK aviation emissions have more than doubled since 1990 while emissions across the economy as a whole have halved.
Even without Heathrow expansion, the CCC says aviation emissions would not fall at all by 2050 under current Government policy.
The committee argues that sustainable aviation fuel, improvements in aircraft efficiency and zero-emission aircraft can contribute to reducing emissions, but will not eliminate them entirely.
Heathrow responsible for around half of aviation emissions
Heathrow currently accounts for around half of UK aviation emissions, according to the CCC.
The committee calculates that the full impact of expansion would account for 6.9% of the UK's remaining carbon emissions in 2050.
It says allowing expansion without stronger measures elsewhere would therefore make achieving national climate targets substantially harder.
Airlines could be required to fund carbon removals
A central recommendation is that the aviation industry should ultimately bear the cost of dealing with its residual emissions.
Where emissions cannot be eliminated directly, airlines could be required to purchase permanent engineered carbon removals, technologies designed to remove carbon dioxide from the atmosphere and store it securely.
The CCC says the cost of decarbonising aviation should be reflected in the cost of flying rather than being transferred to taxpayers or other sectors of the economy.
It also recommends contingency plans if sustainable aviation fuels, aircraft efficiency improvements or carbon-removal technologies fail to develop at the anticipated rate.
Advice requested by Government
The report was produced following a request from the Department for Transport for the CCC's assessment of proposed amendments to the Heathrow Expansion National Policy Statement and the wider role of aviation in meeting the UK's carbon budgets.
The Government launched consultation on its draft Heathrow Expansion National Policy Statement in June.
That policy framework supports additional airport capacity through a Northwest Runway but does not itself grant planning permission for a third runway.
Any expansion proposal would still need to pass the statutory planning process and meet Government tests covering climate change, air quality, noise and economic growth.
Government faces major policy choice
The CCC's intervention creates a significant challenge for ministers because the Government has backed Heathrow expansion as part of its economic growth agenda while also remaining legally committed to the UK's carbon budgets and Net Zero target.
The committee is not responsible for deciding whether Heathrow should expand. Its statutory role is to provide independent advice to Government and Parliament on climate policy.
Ministers must now decide whether to adopt the stronger aviation policies recommended by the committee as they continue work on the Heathrow Expansion National Policy Statement.