A lot of the 19th and 20th century thinking on population growth was completely up-ended by several major advances: first the Haber-Bosch process of fixing atmo

A lot of the 19th and 20th century thinking on population growth was completely up-ended by several major advances: first the Haber-Bosch process of fixing atmospheric nitrogen into ammonia/fertilizer (and now "Nearly 50% of the nitrogen found in human tissues originated from the Haber–Bosch process"), then the discovery of antibiotics (which basically enables modern surgery), modern sanitization, and so on. And since then we've been changing things so fast that I don't think it's easy to predict what things will look like 3 generations from now. What happens if we figure out fusion in 100 years, and fusion power does to several other industries what Haber-Bosch did for agriculture? What if we figure out some major part of human cell senescence and people live to 200-300? Interesting times coming, to be sure. But I'm a bit more optimistic. We figure things out, eventually.