immigration again

It just so happened that just after writing about migration and the UK, I came across this article on Gristmill about the situation in the US and the debate among environmentalists about the issue. Of course the issues in the two countries do share some commonalities and the fact that we have populations that ar bigger than can be sustained by our resource base is the big one for environmentalists. This is what lay behind the Green Party in the UK getting stick a few years back for wanting to reduce immigration, on the basis that the UK would live better within its means at a population max of 30 million [ie about half of present].
The difficulty really is about the demographic profiles of poulation. It might be relatively easy to halve a population but to do so in a way that makes it almost unsustainable: cutting birthrate and not allow young people to migrate in means an aging population who are increasingly unable to help themselves and with too few younger working-age people to support them/us in old age. So the trick is to work globally to reduce population growth and then to sustainably reduce the human population to harmonious limits. There are signs that this can be done. Birthrates go down when infant mortality reduces and there is reasonable hope of welfare [otherwise you need to outbreed the grim reaper of infants and young children and have a number of kids and grandkids to help you in old age]. Better healthcare means older people live productively and sustainably for longer and so need less inputs in other terms. Altoghether, the path to a better world is a humane one -or we can have wars, lots of wars. The latter is the path, in effect that the right are taking as demonstrated by US global policy...
Sierra Club immigration skirmish -- again | Gristmill: The environmental news blog | Grist Magazine