Overall, earth will be home to 8.8 billion people in 2100, two billion fewer than current UN projections.

This is according to a major study that foresees new global power alignments shaped by declining fertility rates and greying populations.

China will fall from 1.4 billion people today to 730 million in 80 years. But Sub-Saharan Africa will triple in size to some three billion people, with Nigeria expanding to 800 million in 2100, second only to India’s 1.1 billion.