Overview

• Using instruments, historical records and hydrological models, the study reconstructs past flows back to 700 CE and evaluates conditions through 2020.
• The downturn since the 1990s is 76% more intense than the closest 16th-century analogue, with droughts that are more frequent and prolonged.
• Annual rainfall declined about 9.5% during 1951–2020, with drops exceeding 30% in India’s western region.
• Reduced groundwater recharge combined with heavy irrigation pumping is highlighted as a compounding driver of lower river flows.
• The authors warn of threats to water and food security for more than 600 million people and urge better climate modeling and adaptive water management.