Some observations on the population crisis

Most people are at least vaguely familiar with this problem.  Birth rates in almost all developed countries, and in some developing ones, have fallen substantially below replacement level.  In some countries populations are shrinking, or would be shrinking if not for immigration.  As other countries become more developed, their own birth rates are headed in the same direction.

The problem

It's obvious enough why this is a problem.  As societies become top-heavy with older people while the relative number of younger people shrinks, the burden of retirement systems becomes ever more difficult to sustain, potentially leading to intergenerational conflicts over resources.  In the US, for example, any effort to cut back the already-threadbare benefits provided by Social Security and Medicare would tip many elderly people over the line into poverty and create a political firestorm.  But once the number of tax-paying workers relative to retirees slips below a certain point, the money will just not be there.  The details would be different in each country, but the fundamental problem is the same.  Also, in many fields, the best and most innovative ideas often come from people in their twenties.  A society with too many aged brains and too few young ones risks becoming less innovative, even stagnant in some areas.

Given enough time, populations will start to shrink.  Some nations would eventually decline so far as to risk being unable to hold their territory against outsiders, or might eventually disappear altogether.  Cultures would lose their robustness.  The status of the French language and culture would be very different in a world where France has forty million people than in a world where it has seventy million.

Finally, there is a psychological issue whose importance I think many neglect.  People need a belief in the future.  A shrinking and aging population creates the feeling that the society is doomed in the long run, that it ultimately has no future.

The next few decades will see a daunting demonstration of the effect of differential birth rates.  According to OECD projections, by 2060 the US will be the world's second-largest economy -- behind India, not China, which will have fallen to third.  China's birth rate is so low that it is doomed to inexorable population shrinkage for the foreseeable future; its paranoid totalitarian regime and the resulting isolation of its people from the outside world are making things worse.  India's vigorous democracy, its strong entrepreneurial culture and open society, and, yes, its demographic vitality and youthful energy, point to an entirely different future.

I do need to address one crank idea which has taken deep roots among the (perhaps over-)educated and among the ideology-addled elements of society -- the concept of "overpopulation".  One could conceivably argue that a few places like Hong Kong or Bangladesh are overpopulated (though the former actually has a high standard of living, and most of the latter's visible problems are due to poverty, not absolute numbers of people), but the world as a whole, and pretty much all individual countries, are not even close.  The famines which racked the world as recently as the 1970s are now a thing of the past, except in freak cases of government collapse (Somalia) or government incompetence (North Korea), even though global population has doubled since then, now standing at eight billion.  The world as a whole has a huge glut of excess food production capacity relative to demand, as was illustrated during Trump's tariff wars, when countries that imported food from the US were easily able to find alternate suppliers, while US farmers struggled to find alternate markets.

The world is in far better shape environmentally than it was fifty years ago (more forest cover, less pollution of most kinds, etc), while the biggest environmental threat that remains, global warming, is due to obsolete energy-generation technology which most of the world is already rapidly transitioning away from.  Food production remains absurdly inefficient, with vast areas of land used not to grow food for humans, but to grow food for animals whose flesh humans consume (a grossly unhealthy practice for a great-ape species such as ourselves).  With full renunciation of fossil fuels in favor of solar, wind, nuclear, and other clean energy, and abandonment of eating the flesh and secretions of filthy animals for the plant-based foods that are natural and healthy for us, the Earth could support twenty or thirty billion people in sustainable affluence indefinitely.

Solutions

I'll start with one "solution" that won't work -- using immigration to offset the decline in the existing population.  Immigration on a large enough scale to actually do this means importing culturally-alien elements in such numbers as to make the existing majority population feel threatened and ultimately provoke a massive political backlash.  In Europe, where the largest portion of the immigrants are Muslim (with a very different culture and also much higher crime rates than the indigenous people are used to), the result has been a rise in nativist political parties such as the AfD, Reform UK, and the Rassemblement National, which are starting to show more support in polling than the old mainstream parties.  There are signs of the same kind of backlash in the US, even though the largest portion of our immigrants come from Latin America, which is much less culturally alien than Islam is.  Existing majorities ultimately will not tolerate what they correctly interpret as a threat to replace them within their own homelands.

It goes without saying that efforts to ban abortion or birth control should be completely off the table.  Sacrificing individual freedom and women's equality is something no civilized country should contemplate.  In any case, the best such policies could do would be to saddle society with millions of children whose mothers did not want them, which would create problems of its own.

Moving on to more hopeful options, I would note that there is one developed country which still has a healthy birth rate -- Israel.  This is not just due to ultra-orthodox Jews (or Muslims) with huge families driving up the average -- Tel Aviv is overwhelmingly secular, yet three-child families are common.  Perhaps we should try to figure out what Israel is getting right that other developed countries are getting wrong.

Another "solution" is one which works automatically.  Within any society, there are subcultures whose birth rates differ from each other.  Imagine a country where the couples in one subculture typically have one or no children, while those in another (likely much more religious and/or conservative) typically have two or three or even more.  Over time, the second subculture will make up a larger and larger fraction of the whole population relative to the first one, and its higher birth rate will increasingly lift the average birth rate of the whole society.  However, there are obvious problems with advanced societies becoming dominated by more-religious subcultures.  And this effect is offset by the tendency of modern people to abandon religion and the values it fosters (over the last quarter century, non-religious people have grown from about 5% of US society to about 30%, and that's obviously not because we're out-breeding the Christians).

In the longer run, there will be a genuine solution -- anti-aging technology.  The aging process is not some immutable fate imposed by the universe.  It's just another medical problem to be solved, like smallpox.  Progress on technology to stop and even reverse aging is much more advanced than most people realize.  At some point, when it comes into widespread use, we will have a world in which aging, and death by old age, will be a matter of choice, not an inevitability -- no one will be subject to them unless they choose to be.  When individuals can live for hundreds or even thousands of years while maintaining the physical and mental vigor of twenty-five-year-olds, the population will stop shrinking and start growing again -- the only causes of death will be murder, accident, and suicide, and even a very low birthrate will more than offset those.  (Some people may choose to refuse anti-aging treatments, for religious reasons or whatever, but inevitably those people will vanish from the population and cease to be a factor going forward.)  But global full availability of such technology is likely decades away at best.  We need other options to address the problem today.

I don't claim to have a comprehensive program for doing that.  But full-bore economic populism would certainly help, insofar as it included (as it should) strong financial and other support for parents who need it.  It would be absurd to "pay people to have" children they don't want, but such support could enable parents to have children they do want but can't currently afford.