An environmental crisis and its cultural impact in eastern China around 6000 years ago

Abrupt climate changes on centennial timescales throughout the Holocene have exerted a profound influence on both the environment and human culture. Prominent climate anomalies between 6 and 5 ka have received considerable attention recently due to their cultural significance. Here, we compiled climate and pollen records from 31 sites in eastern China documenting an environmental crisis around 6000 years ago, named as “the 6.0 ka event”. These records were previously retrieved from lacustrine, loess, peat and marine sediments and speleothem. Our synthesis indicates that the East Asian summer monsoon significantly weakened during this event, while the East Asian winter monsoon markedly strengthened, forced by an intensification of the Siberian high. Consequently, changes in East Asian monsoons led to a cooling and drying climatic condition during the 6.0 ka event in eastern China. This centennial-scale climate deterioration inevitably resulted in the response of vegetation, i.e., remarkable declines of tree cover at mid-latitudes and contraction of evergreen broadleaved forest in subtropical regions, giving way to cool−/drought-tolerant taxa (e.g., steppe grass or conifers). The amplitudes of monsoon and vegetation changes were comparable with those during the 8.2 ka and 4.2 ka events. Furthermore, absolutely dated speleothem isotope records help constrain the period of this environmental crisis between about 6.3 and 5.7 ka, characterized by a double-plunging structure. This environmental crisis was, most importantly, coeval with a decline in the prehistorical human population and agricultural activity, which was, however, followed by an exponential growth soon after. We propose an environmental crisis and its cultural impact in eastern China around 6000 years ago, highlighting the fact that abrupt climate change played an important role in prehistorical culture.