3 reports in this theme, newest first.
On a central measure, 1.2 billion people (16% of humanity) live today where two or more survivability tiers bind on weak institutions; holding today's institutions fixed, warming lifts that to 2.8–4.5 billion by the 2090s, three in five of them in Africa. With 65 armed conflicts in 2025, the most since 1946, and an unsafe equilibrium that could outlast every past civilisation, the cheapest time to choose the buffered path is now.
By 2087, most of humanity will live in sub-Saharan Africa or South Asia. By the 2090s, the median person would live at a mean annual temperature of 26–28 °C, up from 22 °C, and the worst-off quarter beyond 28.5–29.4 °C, with one to more than two months of dangerous heat a year, in air already six times dirtier than the WHO guideline. A low-emissions, high-development path keeps unprecedented heat to 0.6 billion people instead of 3.8 billion.
By the 2090s, 4.3 to 9.3 billion people will live with frequent heat, extreme rain or long dry spells, up from 3.4 billion. The exposed population ages fast: heat exposure among people 65 and over rises nearly tenfold, to 1.3 billion. If schooling keeps rising and protecting as it has, harm falls by 70–84% in three pathways, but under SSP3 protection only holds harm level, and heat harm rises 39%.