It seems like a depressing situation to resolve... even if the political will was there the choices are pretty bleak..
People talk about reduction in birth rates, but apart from the political nightmare of enacting it, the reality is that many countries need more young people, if only to support the elderly who steadfastly refuse to die early
Life expectancy increases decade on decade due to improvements in medical care, but above the age of 65 Alzheimer’s / Dementia increase exponentially..... life expectancy has gone from about 70 to 78 since 1960 (US)...
By the middle of the century the number of cases of Alzheimer’s/ Dementia will have quadrupled, 16.5 % of the US population is over 65 and this is expected to increase to 22% by 2050... it was only 8% in 1950!.... and the oldest end of the old age segment is the fastest growing segment of the population at 12%.
So, looking forward... at a time when we have a massively expanding segment of the population that will require care and support from active working tax payers we also have the need to reduce population... but reducing the Population through reducing the % of young in the population seems massively fraught with risk and will have massive economic problems.
The above is very much a western picture, but one in which many developing countries are progressively heading in the same direction.
All people can do is make the right moral choice within which they feel comfortable.
For instance... I work in the env charity sector, within conservation / nature reserves, live in a small house, no kids, fly probably once a year, perhaps every other or third year longhaul.... I’m comfortable with that, to be honest if I could afford it, both in time and cash, I would no doubt fly more...
but let’s face it, that doesn’t put me in a position to judge anyone else or absolve myself of blame or responsibility.... none of my flights are essential, people’s lives don’t rely on them... I reckon we are all culpable