Eddie Gonzales Jr. – AncientPages.com – Environmental phenomena and their consequences can disrupt social structures and destabilize political systems. This is demonstrated by an interdisciplinary research team using the example of the late Tang Dynasty in medieval China.
Model-based simulation of land-use suitability during the late Tang Dynasty. Source
Migration and mobility due to climate change is not a new phenomenon. This is suggested by an interdisciplinary study in which researchers from the University of Basel also participated. They investigated how hydrological extremes, such as droughts and floods, affected society and politics in China between 800 and 907 AD. They report their findings in the journal “Communications Earth & Environment” .
This period is interesting because it marked the decline of the Tang Dynasty. This dynasty, which lasted from 618 AD, is considered a cultural high point in Chinese history, characterized by a sophisticated administrative system and a flourishing culture. The study focuses on the Huang He (“Yellow River”) region in northern China. Using climate proxy data, researchers identified trends in how the climate there changed during the 9th century AD.
Tree rings as witnesses to history
Tree rings, for example, provide clues about the climate: their structure indicates whether a year was rather dry or rainy. In years with high rainfall, trees grow faster and the tree rings are further apart than in dry years. The older a tree, the further back this data archive extends.
The researchers used existing long-term series of tree-ring data from the catchment area of ??the Yellow River. The reconstructed runoff behavior served as an indicator for hydroclimatic models, particularly for its upper reaches. “The runoff volumes eventually reach further downstream and influence the available water quantities, for example, for irrigating fields,” says lead author Michael Kempf, who has since moved from the University of Basel to the University of Cambridge.
Fatal changes in agriculture
From their analyses, the researchers conclude that climatic changes and an increase in extreme weather events played a crucial role in the collapse of the Tang Dynasty in 907. Increased droughts and floods took a heavy toll on the soldiers tasked with protecting the empire’s outer borders and their families.
“Hydroclimatic extremes directly influence the harvest and the storage conditions for grain,” Kempf explained. Seed shortages and increased food demand quickly pushed supply systems to their limits. A bad year thus also had consequences for the future.
The situation was further exacerbated by the choice of grain crops: people increasingly focused on cultivating wheat and rice instead of millet. Michael Kempf can only speculate about the reasons for this agricultural shift. Perhaps millet was considered more of a poor person’s food than wheat and rice. However, these are less climatically robust than drought-resistant millet, and their cultivation requires more water. “As long as there is enough water, this isn’t a problem, but during prolonged dry periods, shortages occur.” Millet cultivation might have mitigated these negative effects. Instead, the risk of crop failures and famines increased.
These losses could not easily be compensated for with deliveries from other parts of the country, partly because droughts and floods damaged supply routes and caused supply corridors to collapse.
Fleeing from hunger
The population’s malnutrition may ultimately have led to the erosion of border defenses in the north of the empire. “Naturally, the people were weakened and therefore more vulnerable. Due to the military pressure on the outer border regions, they migrated south, where they believed they would find better conditions,” Kempf explained. “This led to political destabilization and likely contributed to the downfall of the Tang Dynasty.”
Michael Kempf emphasizes, however: “Our results are approximations. The actual conditions at that time cannot be reconstructed with absolute certainty. It is a complex interplay of many different factors.”
According to the study, sociocultural and climatic changes can lead to tipping points in the system because the balance is disrupted. This is a development that could occur more frequently in light of current climate change.
Written by Eddie Gonzales Jr. – AncientPages.com – MessageToEagle.com Staff Writer