Overview
- A peer-reviewed Nature Communications analysis using 100 climate-model runs under SSP2-4.5 and SSP3-7.0 projects up to about 750 million people exposed to extreme water scarcity by 2100, most in cities.
- Under high emissions, about 35% of drought‑vulnerable regions are likely to see a first Day‑Zero event within the next 15 years, with many first occurrences in the 2020s–2030s.
- The study estimates around 14% of major reservoirs could dry during initial events, with pronounced vulnerability in Spain, Greece, Turkey, Algeria and Morocco.
- Even meeting 1.5°C would still leave hundreds of millions facing unprecedented shortages, the authors say, calling for conservation, wastewater reuse, rainwater capture and expanded storage.
- Projections focus on surface water and exclude groundwater and glacier buffers, and experts note recovery windows between droughts are shrinking, complicating water-supply planning.