The 10:10 campaign was founded by Franny Armstrong, director of the climate change blockbuster The Age of Stupid. The idea came to Franny while walking through Regent’s Park in London on her way to a debate with UK Climate & Energy Secretary Ed Miliband.

Two things sprang to mind: a recent George Monbiot article had laid out the kind of policies we’d need to cut the UK’s emissions very quickly, none of which sounded impossible. And the Climate Safety report had identified a 10% cut in the developed world's emissions by the end of 2010 as the kind of target we should be aiming for to maximise our chances of avoiding a climate catastrophe.

10% in 2010 also seemed a far more tangible aim than the far-off targets – such as 80% by 2050 – so beloved of policymakers who know they won't be in office for long enough to worry about whether the targets will be met.

Being an impetuous type, Franny dropped the freshly formed 10:10 idea into that evening’s debate with Miliband, but he barely noticed – though quite a few people from the audience emailed later asking about it.

Soon after, Franny and the Age of Stupid team gathered for a brainstorming session in the countryside. Everyone loved the 10:10 concept as it was simple, catchy, meaningful and something that everyone could get involved in – from businesses and hospitals to schools and families.

Within weeks, the 10:10 idea had rippled out across the nation, picking up support wherever it went. Local authorities, individual, celebrities, faith leaders, economists, universities – virtually everyone who heard the plan wanted to be part of it.

10:10 was formally launched on 1 September, 2009, when it took over Tate Modern’s Turbine Hall (and the whole of the Guardian newpaper's G2 supplement). In those first frantic 72 hours more than 10,000 individuals, businesses, schools and organisations signed up.