Planned airport expansion projects will result in European aviation exhausting its 1.5°C carbon budget in 2026 and its 1.7°C budget by 2033 under current growth plans, according to new analysis by Transport & Environment.
With expansion projects either underway or in the planning stage at airports in London, Paris, Madrid, Lisbon, Dublin, Frankfurt and Brussels, among others, T&E said that airport operators are confident that they can fly more passengers while still meeting climate targets.
The group noted, however, that this is wishful thinking, even when accounting for sustainable aviation fuel (SAF) adoption and more efficient aircraft.
‘Cancels out any benefits’
“Increasing traffic volume by adding runways and extending terminals cancels out any benefits from cleaner fuels or efficient engines,” commented Denise Auclair, head of T&E’s Travel Smart campaign.
“No plausible tech improvement can close the gap in time. After this summer’s dramatic heat, fires and drought, governments have a stark choice: they can either make it worse by approving climate-busting expansion, or show decisive action and stop it now.”
Carbon budget overshoots
The most pronounced carbon budget overshoots were identified in Lisbon and Porto, where airport emissions could reach 2.8 times the applicable budget. Dublin, Ireland, followed at 2.6 times its budget.
According to T&E, Lisbon and Porto airports together account for around 80% of Portugal’s aviation emissions. In order for both to remain within national climate limits, the airports would need to cut emissions by 12% annually, rather than expand.
Elsewhere, in the UK, emissions associated with a third runway at London Heathrow between 2035 and 2050 would be equivalent to a full year of Croatia’s economy-wide emissions, T&E said.
In Spain, meanwhile, expansions at airports such as Madrid, Barcelona, Palma and Málaga, which accounted for 66% of Spain’s departing aviation emissions in 2025, are likely to 35 million tonnes of CO₂, equivalent to Portugal’s annual emissions, the group added.
‘Europe’s airports cannot expand as currently planned if countries are to stay within their national climate limits,’ it said. ‘Since emissions come from a shared national budget, every additional tonne of emissions used by an airport above its fair share requires extra efforts from other sectors, such as industry, agriculture or heating.
‘There is also a growing legal risk, as governments approving airport expansions could face legal action for breaching their climate obligations.’
Recommended actions
T&E has recommended three actions to tackle the growing emissions footprint from European airports:
- Governments should halt or refuse airport expansions where they exceed fair-share carbon budgets, and set climate budgets per airport compatible with the Paris Agreement.
- Policymakers should end aviation’s tax exemptions and manage demand: first, by properly taxing jet fuel, applying VAT to tickets, and including all international flights under the European Emissions Trading System; and second, by aligning airport slot capacity with carbon limits and reducing the most polluting flights with low societal value.
- Governments should redirect public money, including from the European Investment Bank and state aid, away from increased airport capacity and towards clean alternatives.
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