Climate variability during the past 2,000 years and past economic and irrigation activities in the Aral Sea basin

International audienceThe lake level history, here based on the relative abundance of Ca (gypsum), is used for tracing past hydrological conditions in Central Asia. Lake level was close to a minimum before approximately A.D. 300, at about A.D. 600, A.D. 1220, A.D. 1400 and since 1960s it is lowering again. Lake water level was lowest during the fourteenth or early fifteenth centuries as indicated by a coeval settlement, which today is still under water near the well-dated mausoleum of Kerderi. Pollen data from riparian vegetation indicate generally wet conditions between A.D. 400 and A.D. 900, intermitted by short intervals with drier conditions (AD 550–600; A.D. 650–700) and riverbanks were again dry from A.D. 900–1150, A.D. 1450–1550, and from A.D. 1970 onward moisture decreased steadily. Irrigation activities were at a maximum between 300 B.C. and A.D. 300 (Classical Antiquity) and between A.D. 800 and A.D. 1300 (Medieval Age) and after A.D. 1960