The impact of immigration is even bigger. All first world nations have declining birth rates now and would reduce their population numbers substantially without immigration. Yet in many countries reach record population numbers on a yearly basis - because millions of immigrants keep pouring in.

I'd rather stop immigration before further driving our birth rates down and leaving world of the future to the low intelligence populations that are currently driving population growth on a global scale. The only ones following this "don't have children because of the climate" advice are those intelligent enough to do so. The whole thing is completely dysgenic in its nature.