Late-Holocene climate change and cultural evolution in Northwest India

The Late Holocene climate variability has played a major role in shaping the fate of civilizations globally including on the NW Indian plains. Abrupt climate drying at ∼4.2 ka BP is linked with the beginning of the deurbanization of the ancient Indus Civilization. However, little is known about the climatic conditions of the Ghaggar-Hakra (G-H) river interfluve region that the rural populations of the Indus Civilization inhabited. In this study, we present a high-resolution climate reconstruction of Late Holocene period using lake sediments from Kotla Dahar, located in the G-H interfluve. Our multi-proxy record suggests that the rural Late phase Indus populations declined in the face of weakened summer monsoon rainfall in the Neoglacial period from 3.3 to 2.5 ka BP. Archaeological investigations suggest that this is also the period when the Iron Age Culture established itself in this region. Our geochemical proxies further indicate that the monsoon recovered during the Roman Warm Period (RWP: 2.5- 1.6 ka BP) and the Medieval Climate Anomaly (MCA: 1.2-0.8 ka BP), which have been previously linked to the northward displacement of the Intertropical Convergence Zone modulated by Atlantic Meridional Oscillations (AMO)-related fluctuations in NH temperatures via its link with the Atlantic Thermohaline Circulation variations and associated interhemispheric heat transport fluctuations.