If you have a spare hour, this lecture is something not to miss. Kevin Anderson, professor of energy and climate change at the University of Manchester gives this year’s University of Bristol Cabot Institute Annual Lecture, and rips into the comfortable assumption that limiting warming to two degrees is still possible. Can we stay within the “guardrail”? Only if you make a series of heroically unlikely assumptions, Anderson suggests. As we head into the Doha COP18 negotiations, this lecture provides a valuable antidote to the rose-tinted spectacles habitually worn by politicians — and, as Anderson points out — many scientists.