How did climate change influence ancient Chinese societies?
Climate does not only sometimes push societies to leave their major cities, which some call collapse, but it also helps societies adjust to a new normal, where food production and even tastes begin to modify based on climate. This is evident in China, where ancient China often did not resemble more recent periods in regards to climate and environmental conditions. Nonetheless, these changes have enriched and brought different layers of social change on Chinese society that have influenced modern China. We can see that modern societies are sometimes composed of layers of different past social but also environmental change that forges new social identities.
Rise of Chinese Complex Societies and Climate
During the long Neolithic period in China (from around 8500-2000 BC), as agriculture began to develop, different types of societies and food production practices formed that focused on millet, in western and central China, and rice, which became more common in central and eastern China. In central China, in particular, evidence indicates shift between millet and rice, where millet is a more hardy crop that can be cultivated in drier periods. In other provinces, there are shifts between rice cultivated in flood agriculture and mixture of using rice and millet. Both taste and climate-induced changes are likely co-occurring in the record, where communal and household-based strategies are also shifting in response to social and climate change that co-occurs. Many of these changes are apparent in central China because it is a region prone or more vulnerable to relatively minor shift in the climate. Until recent period, millet is seen as the food one can use in periods of stress and drought in China, although now in some quarters millet is a more fashionable food than rice.
Early Bronze Age China, at around 2200 BC, was characterised by widespread flooding according to legend. Yu the Great, a legendary ruler, was purported to help manage the great flooding that occurred at this time. There is climatic evidence that by the 4th millennium BCE and going into the 3rd millennium there were shifts to the monsoon rainfall patterns that agriculture would have become more dependent on. Winter monsoons began to wane in this period but less predictable rainfall patterns may have resulted, which could have led to greater instances of flooding where rainfall amounts would vary more greatly from season to season. Water management, at this time, began to utilise a series of earthworks, dams and other irrigation features that likely attempted to mitigate the uncertainty. Excess rainfall could be stored or forced into runoff to avoid catastrophic flooding. This likely helped areas such as along the Yellow River become more controllable and promote settlement. This has been suggested as helping to give rise to the increased social complexity seen at the end of the third millennium BCE and going into the early dynasties of the 2nd millennium BCE. Effectively climatic shifts could have promoted settlement and increased social complexity as societies adapted to better control and manage less predictable rains.
Chinese Dynasties and Empires
During the Shang Dyansty (1600-1000 BCE), researchers have stated the climate became generally warmer. However, there were periodic cooling and likely drier conditions in eastern China. At around 1100 BC, the Shang became weaker as they had to deal with more harvest failures. However, the Shang could have adapted to this and may have withstood such change. Rather, the Zhou, who conquered the Shang and who lived west of the Shang, may have invaded as they felt their societies faced greater threats due to cooling conditions. In effect, the invasion and bellicose nature of the Zhou could be attributed to changing conditions that led to more difficult harvests for them. The concept of the Mandate of Heaven, which formulated that a Chinese dynasty should maintain order in the world, including natural order, may have developed as a way to legitimise rulers. It could also be used to blame rulers as climate conditions became more difficult. This could have happened as the Zhou justified their rule due to the failings of the Shang, as conditions became more difficult. After the cooling at around 1100, climate likely returned to more favourable conditions and the Zhou may have become the long-lived dynasty in Chinese history in part due to more favourable conditions.
Nevertheless, warmer conditions lasted until about 350 CE, covering nearly eight dynasties and ending around the Six Dynasties period. During warmer periods, citrus, such as oranges, may have made their way to China and began to be incorporated into diets. Subtropical herbs and spices were also likely introduced in period when warmer conditions prevailed, as these plants were more easily grown in northern regions that allowed the major centres of China, such as Chang'an in the Han Dynasty. After 350 CE, much colder conditions became evident in northern China, with much harsher winters. This may have led to the development of ice houses for the first time, which allowed better preservation of food over the winter periods. This also likely led tastes in food to change back away from the subtropical foods that could have been grown in other parts of China.
However, over the last two thousand years, as climate has become drier and colder in parts of eastern China, there has been greater evidence that this has led to more periodic locust, famine, and drought occurrences. There has also been higher incidents of epidemics when flood conditions become evident, presumably as bacteria thrive better in warmer and moister conditions.