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 humans, one species of animal amongst millions, have now become the de facto guardians of the planet's climate stability.

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.

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.

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.

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.

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.