The debate on the plan to build the third runway of Heathrow Airport in the UK, which has been in dispute for more than two decades, has started again. After British finance minister Rachel Reeves recently said that the government has support for the construction of the third runway, the debate about it has come to the surface again. Reeves said the third runway would support the country's long-term economic growth, increase investment and exports, and improve connectivity.

Finance Minister Reeves asserted that the expansion of the airport will also improve the economy, and she said at an event in Oxfordshire that the expansion of Heathrow is essential. "Britain can be made a business hub by building a third runway at Heathrow," she said. Environmentalists and some politicians are opposing the expansion of the airport.

They say that the expansion of the airport will increase noise and air pollution. Opponents of the expansion claim that runway construction will make it difficult to meet the UK's climate change targets. However, Reeves claims that construction will proceed in compliance with environmental and climate standards. 

The proposal to expand Heathrow Airport was first brought forward in May 2003 by 'BAA PAC'. The proposal by BAA PAC, Heathrow's operating company, was approved by the UK government in December 2003. The expansion was planned to be completed in 12 years. By 2007, the then Prime Minister Gordon Brown's government had formally endorsed the expansion of Heathrow Airport.

But environmentalists, local residents and political leaders strongly opposed it. They said that there is a danger of increasing carbon emissions, causing noise pollution, and displacing the nearby residents. Despite widespread protests and legal challenges, the government's support remained.

But in 2010, the David Cameron-led government canceled the project, citing environmental concerns. Then in 2016, Prime Minister Theresa May brought the scheme forward again. However, this extension has been continuously reviewed before. Theresa May approved the runway extension, citing mainly the economic benefits.

In 2018, the British Parliament officially voted in favor of a third runway. 415 MPs were in favor of expansion while 119 people voted against it. However, even after Parliament's approval, legal and environmental challenges to airport expansion persisted.

After the vote, Heathrow expansion plans were moving ahead. But in 2020 a court ruled the extension illegal, arguing it was at odds with Britain's climate commitments. This decision of the court forced the government to review the project. But in 2021, the Supreme Court overturned the decision and opened the legal way for the extension of the third highway. BAA PAC subsequently submitted a revised proposal for a third runway at Heathrow Airport in 2023. Which has revived the old controversy.

But Finance Minister Reeves recently said that the government has approved the runway. Supporters of the expansion claim that a third runway would bring significant economic benefits, creating thousands of jobs and establishing the UK as a major international aviation hub, while opponents have raised serious concerns about environmental and social impacts. 

The environmental organization 'WWF' has also pointed out the decision to expand the airport as a serious mistake. It is wrong to continue building expensive projects like the expansion of the airport. "This takes decades, increases carbon emissions and stifles real economic growth," WWF said. With the latest decision, the UK law on carbon emission limits, i.e. 'carbon budget', may also be violated. The carbon budget is the maximum limit that can be emitted into the atmosphere during a certain period of time. 

The UK has adopted a legally binding carbon budget under the Climate Change Act of 2008. Building Heathrow's third runway would increase carbon emissions, which could make it harder for the UK to meet its legal targets. The UK has set a target of 'net zero' emissions by 2050 to reduce climate change. This means bringing the law to zero emissions, or removing from the environment an equivalent amount of carbon that is emitted. Environmentalists are preparing to file a lawsuit against it. So the future of runway expansion is still in doubt.