While all eyes are on human numbers – it’s the rise in farm animals that is laying the planet waste.
So let’s turn to a population crisis over which we do have some influence.
I’m talking about the growth in livestock numbers.
By 2050 the world’s living systems will have to support about 120m tonnes of extra humans – and 400m tonnes of extra farm animals.
Raising these animals already uses three-quarters of the world’s agricultural land.
A third of our cereal crops are used to feed livestock: this may rise to roughly half by 2050.
More people will starve as a result, because the poor rely mainly on grain for their subsistence and diverting it to livestock raises the price.
This might seem counter-intuitive but were we to eat soya rather than meat the clearance of natural vegetation required to supply us with the same amount of protein would decline by 94%.
Producing protein from chickens requires three times as much land as protein from soybeans.
Pork needs nine times – beef 32 times.