A reader writes:

I wondered if you had noticed that the same criticisms applied to global warming also apply to demographic projections.
The last big doom scenario was overpopulation. It didn’t happen.
I enjoyed “America Alone” (as much as it’s possible to enjoy the doom of Western Civ) but I couldn’t help wondering if extrapolating demographic trends is just as flawed as trying to predict the climate.

Well, there’s a difference. Take the demographic crisis in its purest form — Japan, a country with no immigration to speak of. It’s possible to state, as a matter of fact, the number of Japanese 21-year olds available to enter the workforce in 2030 because they’ve already been born, and we know it isn’t enough. It’s not possible to state, as a matter of fact, the climate in 2030.

Furthermore, a demographic decline is a compound phenomenon, unlike the climate. Even if it’s 53 degrees today, that doesn’t prevent it being 87 degrees in 20 years’ time. But, with population, once you reach a certain demographic weakness, you have too few people around to correct the problem in time to save your over-generous welfare entitlements, not to mention culture and language. That’s why demographers talk about “lowest-low” fertility — 1.3 or below — from which no society in human history has ever recovered. If you look at this ranking, you’ll see that Japan and much of Europe are approaching the point of no return.

When I write about the lack of children throughout the developed world, “progressives” often reply that there’s nothing to worry about and our natural ingenuity will ensure that something will turn up in time to save us: more automation, incredibly lifelike robots, clone workers, etc. Yet they’re very reluctant to apply that optimism to the airier speculations on “the climate.”

One final point: Those of us who engage in doom-mongering usually do so in hopes of changing behavior and thus averting doom. That’s where Thomas Friedman’s house comes in. When one examines The Habits Of Highly Successful Warm-Mongers, it’s difficult to conclude they really believe in it at all. From The New Scientist:

My participants so far include a senior adviser to a leading UK climate policy expert who flies regularly to South Africa (“my offsets help set a price in the carbon market”), a member of the British Antarctic Survey who makes several long-haul skiing trips a year (“my job is stressful”), a national media environment correspondent who took his family to Sri Lanka (“I can’t see much hope”) and a Greenpeace climate campaigner just back from scuba diving in the Pacific (“it was a great trip!”).
Intriguing as their dissonance may be, what is especially revealing is that each has a career predicated on the assumption that information is sufficient to generate change. It is an assumption that a moment’s introspection would show them was deeply flawed.