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.

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.

I wonder what sentences judges might hand down at future international criminal tribunals on those who will be partially but directly responsible for millions of deaths from starvation, famine, and disease in the decades ahead.

If substantial methyl hydrate melt begins to occur in the Arctic Ocean basin, then the (carbon) accelerator will be jammed, and there will be nothing we can do to cut the speed of climate change.

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

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.

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.