Avaaz announces that nearly 270,000 people have signed a petition calling for binding global targets for emission reductions.
My feeling (as a signatory who also recommended it to friends) is well great, but actually a quarter million signatures is not really so many. As people have pointed out for years (I wrote about it ten years ago and I am seldom original), when the Chartists petitioned for universal suffrage in Britain in the early 19th century they got more than a million of signatures (out of a population of something like 20 million) using pen and ink, no telephones and horse-drawn transport. A comparable achievement today would probably mean a petition with many tens of millions of signatures (or even more: a twentieth of the global population would be more than 300 million people).
The (much abused example) of the abolition of slavery in the British Empire in the early 19th century is also instructive. It probably cost Britain 1.8% of national income over the next six decades (says Adam Hochschild in a review of Philip Anschutz's movie, citing Chaim Kaufman and Robert Pape: "Explaining costly international moral action"). Contrast that with projected costs of a start on reducing emissions in the direction of acceptable (i.e. towards concentrations below 450, although they may need to be lower to be 'safe'): global annual GDP reduction of 0.12% (IPCC 2007 WGIII) - although in practice the actual cost could prove negative (i.e. a benefit).
[P.S. Solana Larsen says 'Al Gore's petition got more signatures'.]