Thus, humanity has had no fewer than four crystal-clear warnings, by the most knowledgeable people on the planet – and will shortly receive a fifth – that we are bound for disaster.

The new warning of a planetary emergency, due to appear in the journal Bioscience, will focus on actions that must be urgently taken to address the destruction of global life support systems, increasingly fragile water, food and economic systems and the need to eliminate fossil fuels and cut global pollution.

Humanity has the technology and resources to save itself and a habitable planet.

But not, apparently, the resolution nor the brains. Nor a sound enough grasp of the compound nature of the emergency now engulfing us.

Unfortunately, the third warning skates around the greatest elephant on the planet: the fact that it has four times more humans than it can sustain. Unless overpopulation is also addressed, all other solutions must fail.