Besides, the evil empire itself continues to swell. Having increased by more than 50 per cent during my lifetime, the US population is expected to grow from 311 to 478 million greedy Americans within this century. But how is this possible, with a total fertility rate of 2 per cent — slightly below replacement rate?

More awkwardness! Just as in Britain, American population growth is fuelled by...OH, NO! The I-WORD! Virtually all those additional consumers will be the foreign-born and their descendants. For the Left, immigration is sacrosanct, an unqualified Good Thing.

Best estimates suggest that we will run out of fresh water at about 9.5 billion people, a number the UN now expects the species to exceed — and that is only on the unreal assumption that the water is equally distributed. Desalination has become cheaper, but still demands massive amounts of energy, with the attendant emissions. Right-on folks who stipulate that "if we all live on soy pellets" there will be plenty to go around posit a world that will never happen. There's no getting around the fact that the population of 10.2 billion the UN now forecasts we'll reach this century will eat more, require more energy, and generally rubbish the place more than seven billion do. Population is an environmental issue, and if environmentalists are serious about their purported concerns it's time to muck in with the uncomfortable — that big, messy, politically inconvenient world.

A parting thought: population is also an existential concern. Even if it is theoretically possible to sustain 10.2 billion people, is this what we aspire to as a species — to cram as many of our kind on this planet as it will bear? Do we want to apply our ingenuity primarily to solving how to feed and shelter a population half again as large as today's? Isn't there more to nurture in the human race than sheer multitude? Or do we most want to achieve a purely numerical miracle? Because I hate to break it to you, but in this area the insects have got us beat.