The UK government's advisors have warned that expanding Heathrow Airport's third runway cannot be approved unless the aviation industry makes significant changes to how it handles its carbon emissions. The Climate Change Committee (CCC), an independent body that advises the government on climate policy, said the expansion could still proceed—but only if the aviation sector invests in cleaner fuels and supports technologies that remove carbon dioxide from the air. These measures would likely increase the cost of flying. For example, a round-trip to Alicante could become about £150 more expensive by 2050, and a flight to New York could rise by around £400 in today's prices. Once built, Heathrow would become the largest single source of carbon emissions in the UK by 2050. Heathrow Airport insists that expanding the airport and meeting the UK's climate goals are not mutually exclusive. The airport says it will achieve both. However, the CCC chair, Nigel Topping, emphasized that the current conditions for Heathrow expansion are not compatible with the UK's net-zero emissions target by 2050. He called on the government to ensure the aviation industry takes responsibility for its emissions and covers the costs of decarbonization. While the CCC's report cannot block the runway, it urges the government to pass legislation that holds the aviation sector accountable for long-term emissions reductions. The government has launched a consultation to assess Heathrow's expansion against four key criteria: economic impact, climate change, air quality, and noise. The final decision on the runway will be made in a vote in the House of Commons later this year. The £33 billion project would increase Heathrow's passenger capacity to 150 million a year, up from 85 million. A Department for Transport (DfT) spokesperson said any expansion would need to align with the UK’s climate goals, but added it could bring £40 billion in economic benefits and support up to 60,000 local jobs. However, the CCC noted that technologies to cut emissions, such as carbon-removal machines, are not yet available at scale. These machines would need to remove over a third of aviation emissions by 2050, but credible plans exist for only about 1% of that need by the late 2030s. The committee argued that requiring the aviation industry—not the government—to fund these solutions is the fairest approach. While the cost of flying may rise, Topping said the increase would be modest if spread over 25 years, adding that it would be "less than a cup of coffee each way." The aviation industry has pushed back against the CCC's recommendations. Airlines UK’s chief executive, Tim Alderslade, said carriers support the net-zero target but warned that the proposed measures could make flying unaffordable for many. He called for airspace reforms and greater investment in sustainable fuels instead of relying on carbon removal. Some researchers, like Dr. Lois Pennington from the Tyndall Centre, argue that without major reductions in flying itself, the UK may not meet its carbon targets. Despite the CCC’s warnings, the government has signaled it intends to proceed with the expansion, with Chancellor John Healey stating that the economic benefits justify the project. A final vote in the House of Commons is expected later this year, and the plan faces strong opposition from local residents, councils, and even some politicians, including the Mayor of London, who have raised concerns over noise, pollution, and the impact on regional investment.