Overview

• Simulations indicate that under high emissions about 35% of drought‑prone regions could face a first Day‑Zero drought within the next 15 years, with many events projected as early as the 2020s.
• Hotspots include the entire Mediterranean, southern Africa, and parts of North America such as California and Texas, with risk concentrated in urban areas.
• The study estimates up to roughly 753 million people could be exposed by 2100, including about 467 million city residents.
• Researchers project about 14% of large reservoirs could run dry during initial Day‑Zero events, while recovery intervals in hotspots may become shorter than the droughts themselves.
• The analysis draws on 100 climate‑model simulations under SSP2‑4.5 and SSP3‑7.0 and excludes groundwater and glacier buffers, with suggested responses spanning water savings, rain capture, reuse, added storage and efficiency.