So if Crowe’s right, it’s not just ‘big ideas and ambitious plans’ that are dead to our politicians. It’s also, according to the best available science, a great chunk of life on Earth, with neither major party even trying to put forward the measures necessary to end extinctions.

That’s a bleak conclusion – but, in a way, it’s a bracing one since it clarifies, in the starkest possible fashion, the strategic perspectives in front of us.