A green myth is on the march. It wants to blame the world’s over-breeding poor people for the planet’s peril. It stinks. And on World Population Day, I encourage fellow environmentalists not to be seduced.

The actor Jeremy Irons has announced that he plans to make an Al-Gore style movie about the population problem. The screen idol with a social conscience — who famously has seven homes and a pink castle in Ireland – says his inconvenient truth is that “there are just too many of us”.

Overpopulation is driving global warming, mass starvation and accumulating pollution, making the planet uninhabitable. Irons thinks a new plague, like the Black Death 700 years ago, is going to be nature’s way of solving the problem.

He is far from alone in thinking that all efforts to save the world are doomed unless we “do something” about continuing population growth. But this is nonsense. Worse, it is dangerous nonsense.