Once the 'portals of the future close - in Amazonia, Siberia or the Arctic - we will find ourselves powerless to affect the outcome of this dreadful tale.

We no longer need to discuss whether or not it is safe – over a decade and a half with three trillion GM meals eaten there has never been a single substantiated case of harm. You are more likely to get hit by an asteroid than to get hurt by GM food.

If we are to save humanity and the planet from the worst mass extinction of all time, worse even than that at the end of the Permian, we must stop at two degrees.

Our evolutionary psychology preconditions us not to respond to threats which can be postponed until later.

Only by advocating 'politically unrealistic' CO2 concentrations can runaway global warming be avoided. But what is politically realistic for humans is whollymunrelated to what is physically realistic for the planet.

At 1.24 am on 26 April 1986 Chernobyl’s Unit 4 reactor exploded after staff disabled safety systems and performed an ill-advised experiment to check – ironically enough – the reactor’s safety.

Human releases of carbon dioxide are almost certainly happening faster than any natural carbon release since the beginning of life on Earth.