The collective human enterprise depends on our fixing this crisis.

M any of our ruling class are fluent in “sustainability.” They want to build resilient and “sustainable” practices for ranching or fishing, for energy production, and for data centers. And yet, there has been widespread denial of the fact that human population figures are rendering our entire way of life unsustainable.

The figures used by the U.N. to estimate falling fertility rates are built on overoptimistic assumptions. It’s hard-coded into their data sets that no nation can have a fertility rate that dips below 0.5 per woman. It’s also built into their assumptions that the fertility rate in every nation will bounce back long before it dips that low, or that it will simply stabilize. For instance, the U.S. fertility rate has declined from 2.1 to 1.6 since 2008, but the U.N. predicts that we will stay at 1.6 for the rest of the decade. Early results show that we’re continuing to fall at least as rapidly as we have the past decade.

The problem is there is no sign that, say, South Korea is going to start having more children before its fertility rate causes a 75 percent decline in the size of each subsequent generation. And Western fertility rates could start to follow this trend, eventually. The European Union as a whole manages a rate of 1.4, but it is declining quickly. Japan has had a declining population for a few decades, and it’s now resulting in a physical retreat from the boundaries of its civilization. Hokkaido, a northern island of Japan that Stalin once coveted, is being depopulated as people fill in the most populous urban centers.

Absent revolutionary change in how we organize our lives and socialize with one another, population decline will mean ever-increasing social atomization. Family trees that flourished even during historic disasters — wars, famines, etc. — will shrivel in the age of the iPad. Every generation of children will grow up with fewer kith and kin than the last and with a smaller network of emotional or financial support in times of need. The very idea of receiving comfort and consolation in the embrace of a cousin or sibling will be inaccessible to many. So, too, will be the idea of finding one’s footing and feeling of belonging in the world after connecting with a second cousin or aunt who shares some recessed family eccentricities that haven’t found expression in one’s nuclear family. That is, the vast majority of humans in the future will have fewer opportunities than we did to practice mutual care in an intimate context. As the familial world retreats, what will predominate in people’s formation are their commercial and political relations with strangers. We might even expect the values of commercial relations to invade and further poison family life.

If a fish farm were set to become so impoverished of fish in so few generations, dramatic action would be taken by everyone in charge of the enterprise to improve its reproductive environment. After all, the whole enterprise depends on it! Nobody on earth has that kind of power over the collective human enterprise. But it should worry us that we may come to wish that there were such an authority when the decline enters a more serious phase, when retreating human civilizations turn to desperate wars for territory and resources, or when the experience of atomization and breakup inspires millenarian religious cults.

We should be asking big questions. Instead, people are folding their hands, talking about a minor tax incentive here or a little baby bonus there. Compared with the ambitious social reformers and futurists of the previous century, the ones who imagined much of the world we are in today, we are quite timid. Name a single person who is imagining or agitating for a high-fertility future of loving households. There are none. The only kind of high-fertility future we imagine is one in which we render our fluids to a factory to produce and provide for a posterity we’ve abandoned.

Maybe that’s one of the symptoms of the decline already setting in. Before becoming an older society, we become a more geriatric one. Our steps become smaller and more fearful. Big urgent changes? That’s for someone else. Not us. The great machine of society is noisy and dangerous to alter. We don’t dare interfere, even if we know it is presently engaged in the work of burying us.