"A brief and rapidly closing window of opportunity” is how a new major climate change report from the UN described the effect of rising emissions. Already 40% of the world's population is "highly vulnerable" to the impacts, according to the latest report from the International Panel on Climate Change. And it’s all happening much more quickly than previously thought. Sophie Eastaugh and Jordan Dunbar discuss the findings with a panel of experts. How much more serious do things need to get before action is taken? Produced for the BBC World Service by Darin Graham.