10:10 Favorite 

Environmental activist Franny Armstrong's brainwave came as she was walking to a debate with the then Secretary of State for Energy and Climate Change Ed Miliband. She had read a report saying that the developed world must cut its carbon emissions by 10% by the end of 2010 to avoid passing the tipping point. Armstrong, 39, dropped her idea to start a campaign into the debate. 10:10 was born. It was the obvious next step for the woman whose apocalyptic film The Age of Stupid had already galvanised support for climate activism.

The simple idea for immediate practical action took off, with thousands of businesses and institutions and more than 100,000 people pledging to cut their carbon emissions by 10%. Days after the coalition government was formed, David Cameron announced central government would do the same. The campaign is now active in more than 40 countries.