The London Heathrow Airport expansion could have “the worst outcome for the environment”.
WWF-UK made the comment after the Airports Commission recommended a new runway.
Chief Executive David Nussbaum said: “It would lead to the greatest increases in noise, in air pollution and in climate-damaging CO2 emissions. It will not make Britain more prosperous but it will make it impossible for the aviation sector to play its proper role in meeting the UK’s emissions targets.
“The greater the emissions from aviation, the greater pressure there will be on other businesses to reduce their CO2 emissions even further.”
Friends of the Earth added the expansion would have a “hugely damaging impact on local people and their environment and would be a step backwards in UK efforts to tackle climate change”.
Head of campaigns Andrew Pendleton said: “Airport expansion also risks worsening local air pollution levels which already breach legal limits.
“The UK will be a laughing stock if it turns up at crucial climate talks in Paris later this year, claiming global leadership while at home having nodded through new runways, killed its onshore wind industry and foisted fracking on communities that don’t want it.”
Transport Minister, Patrick McLoughlin, said the government is trying to balance local interests against the wider, longer term benefits.
“We will come back to Parliament in the autumn to provide clear direction to everyone on the government’s plans.
“This is a vital moment for the future of our aviation industry. All those with an interest in this important question are expecting us to act decisively.”