Not having children is the best contribution to reducing the effects of climate change due to overpopulation.
Totally unselfish of people to do that. It's far better than throwing a few cardboard boxes in a green bin anyway.
As for care in old age. Don't make me laugh, that is not happening now and we are importing the majority of carers and medics from overseas as we speak. So we are reducing overpopulation in other countries. Win win.
And it is an individual choice. I reckon people want to actually live, not exist these days, and if that means remaining child free, well who can blame them. Procreation is a very expensive business, and unless and until Government policy makes it economically viable, the choice will often be not to do it.