A public inquiry into plans to expand Stansted airport in Essex is due to begin today.
The inquiry has been launched after Uttlesford district council rejected the proposals by the British Airport Authority (BAA) on environmental grounds.
BAA wants to increase annual passenger numbers at Stansted from 25 million to 35 million, claiming that the move is necessary to meet demand as more and more people wish to fly.
The airports operator is also seeking permission to increase the number of air traffic movements allowed at the airport from 241,000 to 264,000 a year.
However green campaigners insist the local environment will be damaged if the plans go ahead.
Supporters of the fight to prevent the proposed expansion, including campaign group Greenpeace, the Campaign to Protect Rural England and former environment minister Michael Meacher, also warn in a letter to the Times that the outcome of the public inquiry will have implications "far beyond" north Essex.
"If Stansted were permitted to expand to maximum use of the existing runway, the local environment would suffer, the national economy would suffer and we would have taken a giant step backwards in the battle to combat climate change," a spokesman for the Stop Stansted Expansion campaign told BBC News.
The comments were echoed yesterday by Greenpeace aviation campaigner Emily Armistead, who stressed that the government should block the further expansion of the country's airports in order to tackle global warming.
"Our government simply has to join the dots and call a halt to airport expansion - if they don't there's simply no way we are going to ward off catastrophic climate change," she warned.
Ministers are currently faced with the dilemma of how to meet increasing demand for cheap air travel with the need to protect the environment and the outcome of the Stansted inquiry is likely to be of particular interest to policymakers.
In a statement ahead of the start of the inquiry, BAA insisted that it could achieve growth at Stansted in a "sustainable way".
"There are huge social and economic benefits to be gained from growth at Stansted and this is an exciting opportunity that should not be lost," the company stressed.