Chinese climate chaos

Climate change caused collapse of complex Chinese culture.

The Liangzhu culture of China’s Shanghai Delta region developed before 3250 BC, a society known mainly for its prestigious burials. Liangzhu potters were some of the finest of the day, famous for their finely made black polished vessels made not by hand, but with potter’s wheels.

Its principal city was an important regional centre with extensive commercial and political contacts to the north and south. This society was remarkable for its sophisticated water works, which included a complex system of navigable canals, dams, and reservoirs that nourished and maintained extensive irrigation works and year-round cultivation. Liangzhu flourished until about 2000 BC, when it suddenly disappeared from the Lake Taihu area, for reasons that were a mystery – until very recently.

Archaeological work revealed a widespread clay layer that overlay much of the city’s ruins, which suggested that Yangtze River or ocean floods inundated and destroyed the flourishing civilization. Enter the palaeoclimatologists. Geologist Haiwei Zhang sampled stalagmites from caves southwest of the Liangzhu site and recovered a period of exceptionally high rainfall between 2345 and 3224 BC. Uranium thorium dating using isotopic carbon established that the Liangzhu culture collapsed in about 2300 BC during this period of very heavy rainfall. Massive monsoon rainfall caused such severe Yangtze flooding that even the most sophisticated dams and canals collapsed. The city was inundated, much of it being swept away. Ultimately, Liangzhu society fell apart and people moved away, with many presumably perishing in the floods.

Image: The stalagmites from caves located southwest of the excavation site, which have provided the palaeoclimatic evidence for the collapse of the Liangzhu culture.

Credit: Haiwei Zhang