Update (12:40): Watch the video
Seizing the rare opportunity to welcome some good news, Greenpeace climbers scaled the front of St Pancras station this morning and hung a huge banner proclaiming 'YES' in 3-metre-high letters to show support for the new high-speed rail link to Europe, which finally got under way today with a jaunt to Paris and back for selected journalists and politicians - including PM Gordon Brown.
I'd be lying if I said there wasn't slightly more to our presence at St Pancras than unqualified support for train travel, important though it is in the battle against climate change. The banner's strap line read "PS Gordon - no need for that third runway", a not-so-subtle reference to the proposed expansion of Heathrow airport that Mr Brown will be asked to decide upon in a few months' time.
For while the PM is happy to take credit and make political capital from associating himself with popular transport developments like the high-speed rail link, he's also supporting a new runway at Heathrow which will increase traffic at the airport by 70 per cent and render his own government's commitment to cutting CO2 emissions completely impossible.
Taking the train causes on average ten times less damage to the climate than flying, yet flights from Heathrow to locations easily accessible by train - such as Edinburgh, Brussels, Glasgow, Amsterdam, Paris and Newcastle already total over 100,000 a year. If passengers taking these unnecessary flights could be transferred to the train, there would be no need for Brown's 3rd runway, which is intended to cater for smaller aircraft flying short-haul journeys.
Flying is the fastest growing source of UK CO2 emissions, and because aviation emissions are released at altitude they do far more damage to the climate than CO2 emitted at ground level. In fact the Tyndall climate research centre's latest figures suggest that, if aviation expands as projected, we will have to make the rest of the economy zero carbon by 2050 to effectively tackle climate change.
Mr Brown doesn't really have a leg to stand on on this one - he can't even fall back on the last refuge of the political scoundrel, that it's popular with the public. Opinion polls have consistently shown that over 60 per cent of people don't want to see airports expand. In the latest IPSOS MORI poll last month the figure had risen to 70 per cent.
So if you give the go-ahead for the third runway you will have the grateful thanks of British Airways management, and complete loss of respect from almost everybody else. Hmm, difficult choice that one...
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, why not do both just to ram the point home, it shouldn't take you more than a few minutes. Remember - one is good, but two's even better!
• 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' corporate profits!