Today, I'm launching my campaign to be Mayor of London. As the Green Party candidate, you'd expect it to be full of plans for better bikes, more recycling and the usual green stuff. And yes, I do plan to have a lot more of all of these.

However, without an equal measure of social justice, environmental policies alone won't work. A Green London also has to be a more affordable London, with cheaper transport fares, free insulation and wide range of other plans that bring cutting emissions together with cutting the cost of living. That's why I was to be found this morning (Friday) outside city hall with a big £20 note to prove it.

Yesterday, Ruth Kelly also launched a big plan for London. Unfortunately, the government’s plans for the expansion of Heathrow airport have a lot less to offer Londoners than my Mayoral policies. In fact, in terms of noise, air quality and climate change, adding a third runway and a sixth terminal to what is already the world's busiest airport, would be catastrophic.

Since they are also based on a seriously flawed economic case, I'd go so far as to say the plans amount to a direct attack on London and everyone who lives here.

Far from creating jobs or improving profits for local businesses in London, the cost of the Government's grand project at Heathrow will be illness due to increased pollution in West London, more intrusive and stress-inducing noise, which already extends as far East as Finsbury Park, and economic damage to the whole city.

The Government's economic case based on assumptions about both the benefits of aviation and the predicted demand. For every pound spent by tourists in the UK, we spend £2.20 overseas. Government's plans to treble air travel are likely to mean that as well as people taking off, money will be flying out of the British economy - with a predictable effect on jobs.

In essence then, a highly dubious economic case is being constructed to justify a catastrophic impact on people's environment, now and in the future. Air pollution kills, persistent noise increases risk of depression, and climate change is already ruining and destroying hundreds of thousands of lives across the globe. That a minister will happily expose ordinary people to all of this just to keep the aviation lobbyists happy shows just how skewed the Government's priorities are.

As much as the words 'government consultation' send most people to sleep, Greenpeace proved this year over nuclear power that, to be legal, a public consultation process has to have teeth. In the face of a massive rejection from Londoners of their plans for Heathrow, they would be on very shaky ground if they did not listen. So, where a sliver of democracy breaks through what appears already to be a stitch-up, we owe to ourselves to use it. 

I'll be backing the Stop Heathrow Expansion campaign and urging all Londoners to stand up for their city by answering the consultation with a big, fat 'No', in opposition to this negligent scheme.