The issue is that the immigrants are also having less children, and the countries where they're from are also drastically reducing their birth rates. Honestly,

The issue is that the immigrants are also having less children, and the countries where they're from are also drastically reducing their birth rates. Honestly, as an environmentalist it's not a bad thing at all, since the peak in resource consumtion will come about either because of a voluntary population reduction, or catastrophic mismanagement of growth. However, we probably have never had a similar situation in human history, and I don't know how our economies will adapt.