> By 2050, China will have lost one-third of its working-age population. Meanwhile, the U.S. will bestride the earth as the youngest industrialized nation after India.
How are we divining the mating habits of people born in 2020 to 2030's US?
The age distribution in China is not that far off from the US[1]. This gives China a similar entitlement expenditure per person as in the US, but without the same level or distribution of income.
US population growth has been outpacing China and Europe for the last decade [2]. If trends stay about the same (no plagues, massive wars, or other major changes in population), the population growth happening today will translate to growth in the work force 20 to 30 years from now. Note: population growth includes immigration, which is something the US experiences more of than China or Europe.
In a nutshell, we expect the Chinese demographics to shift older faster than the US. This raises questions on how China will fund services, entitlements, etc 30 years from now (which is what I imagine Joffe was getting at).
By assuming they evolve in the same way they've been evolving since WWII. While it may not look like it in San Francisco, but there are huge groups in the country, white and non-white that are having quite a few kids. Not enough to make population rise, but enough to keep it stable. It seems a vast number of people prefers a small city or medium city lifestyle with 3 kids. The weird thing is that this will make the experience of so many San Franciscans today a feature of the first half of the 21st century too. A hell of a lot of new immigrants will come from a pretty strict religious background and feel like releasing some steam in their early twenties. The influx of people like that should continue for another 20 years at least.
So the assumption is that the population of the US will continue to climb slowly due to natural growth, accelerated a little bit, but not much, by immigration.
Now if you look at the EU or China, they have a very different story. The EU has been stuck in a massive population drop rate (roughly approaching next generations being 50-70% of the previous generation for all of Western Europe, coupled with massive immigration numbers that make the numbers barely stable). That means that in a lot of countries in Western Europe, approaching 50% of the <20 population is of foreign origin, first or second generation, mostly from Northern Africa and the middle east. These numbers look scary, yet in the major cities, Paris, London, ... they look a lot scarier still. If the "unemployed youths that don't fit into society leads to revolution" crowd is correct, Europe has maybe 5-10 years left before that happens. There may be a further delay because of the simple fact that European mistreatment of the poor is still a lot better treatment than islamic nations' treatment of the middle class and the rich. So the immediate immigrants are actually quite content to be abused. Their children, however, are not.
China is in a pickle. They need, absolutely need, a lot of population growth to avoid disaster, but in absolute numbers everything they built is filled to the brim. They are trying to use the "one child policy" to spread out the population by relaxing it for ethnic Chinese in the outer regions, like Xinjang or Tibet. So if you are Chinese and want kids, if you move there and get a job there (Chinese control most businesses and employers are at least somewhat racist, so it's not impossibly hard), the government will let you do that, up to 5 kids in some places. The purpose is, of course, slow ethnic cleansing, but given that it's China, the UN will never even mention it.
I call [citation needed] on your EU demographics. The EU has not been "stuck in a massive population drop rate": the EU population actually grew by 3.7% between 2002 and 2001, with only 6.3% born outside of the EU. And Eurostat forecasts the population to grow very modestly between now and 2060. (Source: http://en.wikipedia.org/wiki/Demographics_of_the_European_Un...) Of course, those predictions don't mean all that much, since "demography is destiny" only in retrospect: growth trends can and do change. (E.g. the French birth rate has gone up in recent years.)
To be honest, I think you may have read too much Mark Steyn. There is little cause for demographic apocalyptics, including the tired "Muslims are going to revolt/take over" kind. In fact, a flat or slightly declining population is probably a blessing (e.g. from an environmental perspective).
The oroblem with non-whites not quite fitting in is real, though, and much worse than in the US. Besides color, muslims are pretty hard to assimilate, so there will be not only color-based racism but also cultural ethnocentrism.
Imagine you have the problems of economic class and then add another dimension of cultural class. Society becomes much more fragmented. The new dimension is not really worse than economic class, but class alone is already unpleasant. It will turn out all right, I guess, but there will be minor persistent problems for a long time.
You should note I make a difference between natural population growth and immigration. The EU's natural growth is nothing short of disastrous, and this is made up for with immigration.
"the government will let you do that, up to 5 kids in some places."
This is not true, actually if you are Han people, no matter where you move to (within China), you still can only have one child unless you married to "ethnic minority" who no need to follow "one child policy".
How are we divining the mating habits of people born in 2020 to 2030's US?