Abruptly increased climatic aridity and its social impact on the Loess Plateau of China at 3100 a B.P

A multi-disciplinary research with integration of the theory and methods of climatic change and history was carried out in the southern Loess Plateau of China. High-resolution soil-sedimentary data define an abruptly increased climatic aridity at 3100 a B.P. on the southern Loess Plateau. It was caused by a shift from the dominance of the maritime monsoon to the continental monsoon in the East Asia. The marked aridity induced a considerable deterioration of environment and degradation of land resources. Consequently, both the livestock failure of the nomadic tribes in the north and the crop failure of the Han Chinese in the south resulted in large-scale nomadic southward migration, and dislocations of the political capital and capital cities of the predynastic Zhou culture. Land use of arable farming was replaced largely by pastoral farming on the plateau. The combination of severe drought and resultant great famine was the fundamental cause of social instability and eventual collapse of the Shang Dynasty at 3000 a B.P. This suggests that the impact of abrupt climatic change was profound at 3100 a B.P. in the present semi-arid zone.