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New Study Ties Indus Valley’s Long Decline to Repeated Basin-Wide Droughts

Using cave and lake records paired with climate–hydrology models, researchers reconstruct centuries of reduced rainfall and streamflow.

Overview

  • Published in Communications Earth & Environment, the study integrates speleothem and lake proxies with long-running climate and hydrological simulations to map basin-scale water availability.
  • Reconstructions indicate regional warming of about 0.5°C and a 10–20% drop in annual rainfall, producing sustained reductions in river discharge across the Indus basin.
  • Four prolonged drought episodes between roughly 4,450 and 3,400 years ago each exceeded 85 years in duration, with the most severe lasting 102–164 years and impacting over 90% of the region.
  • One 113-year drought dated to approximately 3,531–3,418 years ago aligns with archaeological evidence for widespread deurbanization of major Harappan centers.
  • Findings point to population dispersal toward the Himalayan foothills, the Ganga plains, and coastal western India with smaller communities and drought-tolerant crops, while proposed Pacific–Atlantic teleconnections weakening the monsoon remain under study.