PLANS to expand UK airport capacity are based "on a wing and a prayer" and "not rooted in the real world", two environmental groups have warned.
The reports have challenged the Airports Commission's claim it is possible to build a new runway and still meet Government's climate change targets.
The warning, from the RSPB, nature charity the WWF, and the Aviation Environment Federation (AEF), says building a new runway in the South-East would worsen the North South divide, as growth at regional airports would need to be constrained to ensure CO2 emissions fall to their 2005 levels by 2050.
The Airports Commission is considering where airport expansion should go ahead, which includes potential new runways at Heathrow and Gatwick.
Cait Hewitt, AEF deputy director and report author, said: "The commission and future Government have a choice to make.
"They either allow aviation expansion in the South-East and heavily constrain regional airports or let them grow within the capacity they already have but don't build any new runways.
"However, climate change limits mean you can't do both."
The plea comes after bosses at Durham Tees Valley Airport (DTVA) last week told The Northern Echo any Airport Commission changes must include cuts to passenger duty.
Peter Nears, DTVA's atrategic planning director, said any moves by the commission should also place greater importance on regional services ahead of international operations.
The airport lost its daily BMI service to Heathrow in 2009.
He added: "Ministers must look at ensuring there are robust legal and planning regimes in place if increased capacity in the South-East is to improve access from regional airports through the ring-fencing of slots."