Is the world's target of limiting global warming to 2 °C too high, or too low? Does it even make scientific sense? The consensus around the target, which was agreed at climate talks in Copenhagen in 2009, seems to be coming unstuck.
Back in October, US climate analysts David Victor and Charles Kennel called it scientifically meaningless and politically unachievable. We should get used to the idea of something warmer, they said.