Many thanks to Graham Davey for passing on the link to this excellent animation. The website a page with the full script of the film plus supporting references.
Wake Up, Freak Out - then Get a Grip from Leo Murray on Vimeo.
It turns out that the way we have been calculating the future impacts of climate change up to now has been missing a really important piece of the picture. It seems we are now dangerously close to the tipping point in the world's climate system; this is the point of no return, after which truly catastrophic changes become inevitable