The interplay now between climate change, environmental catastrophes (even in developed countries. viz bush fires in Australia), global pandemic, nasty increases in populist governments and policies, huge numbers of peple living in absolute poverty and poor health and well-being, the young-biased age structures of populations in developing countries (and the impacts of elderly structures in some developed countries (e.g. Italy, Japan) all combine to impact on global human population; there are complex interactions and feedbacks, but in the end it is sheer numbers of people that have to be addressed.