- The Climate Change Committee says Heathrow expansion is incompatible with net zero under current policy, but has stopped short of ruling it out entirely.
- Its conditional pathway places the cost of sustainable aviation fuel and engineered carbon removals on the aviation industry.
- Engineered removals would deliver 36% of the required mitigation in 2050 – making airport policy a potentially significant source of demand for an industry that barely exists at scale.
Heathrow should not be allowed to expand unless ministers require the aviation industry to reach net zero by 2050 and pay for the sustainable fuels and permanent carbon removals needed to achieve it, the UK’s statutory climate committee has said.
The Climate Change Committee concluded that there was “no credible pathway” for expansion within existing policies. It nevertheless set out conditions under which a third runway could be reconciled with UK carbon budgets, combining lower demand growth, aircraft efficiency, sustainable aviation fuel (SAF) and engineered removals.
The committee also called for the climate test in the draft Heathrow Expansion National Policy Statement to be strengthened so that it explicitly covers the legally binding 2050 net-zero target – not only nearer-term carbon budgets.
“Our advice today is clear – Heathrow expansion is not currently compatible with the UK’s Net Zero target,” CCC chair Nigel Topping said. “Government needs to ensure that the aviation industry takes responsibility for the emissions it creates and bears the costs of decarbonisation.”
Aviation emissions have more than doubled since 1990, while emissions from the UK economy as a whole have roughly halved. Heathrow currently accounts for around half of domestic aviation sector emissions, according to the CCC.
Betting big on carbon capture
Under the committee’s proposed 2050 pathway, engineered removals account for 36% of the emissions reduction needed from aviation. Lower growth in demand contributes 24%, with efficiency improvements and SAF each providing 20%.
That distribution is significant. It means Heathrow expansion would not be rendered climate-compatible principally by zero-carbon aircraft. Instead, the sector would purchase substantial volumes of removals to counterbalance emissions that remain technically difficult or prohibitively expensive to eliminate.
The CCC said the industry should face the full cost of decarbonisation by 2050, with those costs introduced progressively from now. Its modelling suggests that, if passed through by airlines, SAF and removals could add approximately £150 to a return flight to Alicante and around £400 to a New York journey by mid-century.
Heathrow argued that expansion must deliver both growth and net zero, while Airlines UK warned that the proposed cost burden could place flying beyond the reach of many households. The government is not legally obliged to adopt the CCC’s recommendations.
The advice nevertheless establishes a demanding test for ministers. SAF currently supplies only a tiny fraction of global aviation fuel and remains materially more expensive than fossil kerosene. Engineered removals such as direct air capture with carbon storage and bioenergy with carbon capture and storage (CCS) are even less mature commercially.
The committee therefore wants contingency policies if either technology scales more slowly than expected. It also recommends coordination with the EU and the International Civil Aviation Organization to limit carbon leakage and competitive distortions.
Crucially, investors – not passengers or taxpayers – would be expected to bear the commercial risk if future demand proves insufficient to support the expansion. That stipulation is intended to prevent government from relaxing climate policy simply to protect infrastructure revenues after construction.
The decision could have consequences well beyond aviation. A binding requirement for airlines to buy permanent removals would create a major long-term customer for UK CCS infrastructure. A stronger SAF obligation could similarly support synthetic fuel and biorefinery projects.
But airport expansion would then become inseparable from the timely delivery of those industries. Ministers would effectively be approving additional aviation capacity today against an expectation that large-scale fuel and removal markets will be available decades later. The CCC’s key message is that this risk can no longer be carried by the rest of the economy.
