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.

You'd be forgiven for thinking that climate change means we'll have to sacrifice our creature comforts. But it doesn't have to be that way.

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.

Unless we decide to reduce greenhouse gas emissions within just a few years from now, our destinies will already be chosen and our path towards hell unalterable as the carbon cycle feedbacks... kick in one after another.

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.

Silent Summer - a never-ending heat wave, devoid of birdsong, insect hum, and all the weird and wonderful living noises that subconsciously keep us company.

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.