A major new analysis has concluded that the proposed expansion of Heathrow Airport with a third runway presents a direct threat to London's ability to meet its own climate change targets. The report, commissioned by environmental groups, warns that the increased flight capacity would shatter the city's carbon budget for aviation.
Aviation Emissions Set to Exceed London's Entire Allowance
The core finding of the report is stark. It calculates that if the third runway goes ahead, carbon emissions from flights departing from London airports would consume 127% of the entire aviation carbon budget set for the capital for 2030. This budget is a key part of London's plan to become a net-zero carbon city. The analysis suggests Heathrow expansion alone would push London's aviation emissions to nearly 8 million tonnes of CO2 equivalent by 2030, far exceeding the recommended limit.
The report was commissioned by a coalition including the No 3rd Runway Coalition, Possible, and Greenpeace. It was presented to the London Assembly's Environment Committee, increasing political pressure on Mayor Sadiq Khan. While the Mayor has previously expressed personal opposition to the expansion, campaigners are now demanding he uses all available planning and legal powers to formally block the project.
Mayor Khan Under Pressure to Take Formal Stance
Paul McGuinness, Chair of the No 3rd Runway Coalition, stated that the evidence leaves no room for ambiguity. "The third runway is a direct threat to London's carbon budget aims", he asserted, calling on the Mayor to transition from passive opposition to active intervention. The groups argue that the Mayor's spatial development strategy, known as The London Plan, should be leveraged to refuse the expansion on climate grounds.
A spokesperson for the Mayor of London reiterated Sadiq Khan's long-standing opposition to the third runway, citing unacceptable impacts on air quality, noise, and climate change. They confirmed the Mayor believes the government should instead focus on improving rail links to existing airports across the UK. However, the environmental coalition is pushing for a more concrete, policy-driven block against the development.
Heathrow's Counter-Arguments and the Road Ahead
In response to the report, a spokesperson for Heathrow defended the expansion plans. They argued that a modern and expanded Heathrow is compatible with the UK's goal of reaching net-zero aviation by 2050. The airport claims its plans include stringent environmental conditions and that the government's own Jet Zero strategy accounts for airport growth. They position the third runway as vital for the UK's economic recovery and future trade.
This clash sets the stage for a significant political and legal battle. The report fundamentally challenges the notion that increased aviation can be reconciled with near-term, legally binding climate commitments. With the London Assembly now formally examining the evidence, the pressure on all decision-makers, from City Hall to Westminster, is set to intensify as the planning process for the controversial runway continues.
