Today the government begins its long-awaited consultation process into the need for a third runway at London's Heathrow Airport. Strangely enough, given Gordon Brown's recent public declarations that tackling climate change is right at the top of his agenda, it's already looking as though Heathrow expansion will be given the go-ahead. But then documents we've been given by Justine Greening MP show just how closely the government has been working with BAA on preparing the consultation.

This move towards a third runway is despite the fact that it will mean a 70 per cent increase in flight numbers and the resulting rise in climate change pollution will be equivalent to the entire annual emissions of Kenya. Worse still, the bulk of the additional 500 flights a day from Europe's busiest airport will be short-haul hops to cities like Paris, Brussels, Edinburgh and Newcastle - all easily reached by rail.

There's only one reason for a third runway - to increase the profits of the BAA and the major airlines, in particular British Airways, who operate these routes. And documents we've obtained from BAA under the Freedom of Information Act show just how closely the company and the Department for Transport (DT) have been working together to ensure the runway gets built. Here are just some of the highlights:

BAA officials have written parts of the consultation.

BAA supplied the data for calculations of noise and pollution that inform the premise of the consultation document. No opposition groups have been permitted to challenge the data.

The DT and BAA have drawn up a 'risk list' of threats to the building of the third runway. The list includes the 2M campaign, the group comprising councils representing 2 million people opposed to the plans.

They've even set up a joint body – the Heathrow Delivery Group – aimed at steering the plans through the consultation process.

Honestly, this kind of duplicity almost beggars belief. Flying is the fastest growing source of greenhouse gas emissions in the UK - unless we bring it under control we have no chance of meeting the ambitions CO2 reduction targets that the PM only this week pledged to reach, or even exceed. And Heathrow is only one of more than 20 airports around the country in the process of submitting expansion plans. The Tyndall climate research centre has calculated that if aviation continues to expand as projected, Britain will have to totally decarbonise the rest of its economy by 2050 to effectively tackle climate change.

What you can do

Let Gordon Brown know that he's a public servant and that we expect him to act in our interests, not help big business maximise its profits. There are two ways you can do this - send him a video message or write him a letter. In fact, to ram the point home why not do both? It shouldn't take you more than a few minutes.

Join the thousands who want to stop Heathrow expansion by adding your comments to our video wall. Make your voice heard!

Write to Gordon Brown and tell him that minimising the effects of climate change is more important than increasing British Airways' profits!

Watch last Tuesday's Newsnight debate about Heathrow between Greenpeace's John Sauven and energy minister Malcolm Wickes.

Find out more about our Stop Heathrow Expansion campaign.