London's Heathrow Airport has been much in the news recently, thanks to the UK government's controversial plans to develop a new third runway.

WWF believes that allowing the number of flights using Heathrow to increase from 473,000 to 700,000 a year will lead to a huge rise in emissions that contribute to climate change, as well as producing more noise and pollution for people living around the airport. All this at a time when we should be rapidly cutting our emissions if we are to avoid the worst impacts that climate change will have on people and the natural world.

We're also concerned that the consultation exercise being run by the government fails to give people a chance to say what they really think about expanding the airport. In 2003, the government announced that it wanted to build a third runway; now its public consultation concentrates only on highly technical questions and gives no room to discuss key issues such as climate change.

What's more, new research for WWF raises serious questions about the economic benefits of the new runway. We've already shown that many businesses are increasingly looking to use videoconferencing to cut down on flying – which suggests the additional runway isn't needed as much as is claimed. Now we've taken a closer look at the way the government has worked out the economic benefits – and we've found that the case for expansion rests on some questionable assumptions.

That's why we are asking our supporters to register their opposition to a third runway by signing a petition at stopheathrowexpansion.com

• Watch film exploring new report and WWF's One in Five Challenge
• Read more about WWF research into the economic benefits of expanding Heathrow
• Progress so far on Heathrow
• Why is WWF-UK concerned about aviation growth?