Climate Changes of Northern China Being Reconstructed During "5000-year" Chinese History----Chinese Academy of Sciences

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Climate Changes of Northern China Being Reconstructed During "5000-year" Chinese History

Jun 07, 2021

During its long lasting “5000-year” history, China has experienced a series of centennial-scale rise and fall of dynasties, unifications and divisions, war and peace and south-north migration of northern nomads. Climate changes have long been considered an important driver of these historical cultural changes through affecting phenology and land productions, especially for ancient China.

As early as the 1970s, CHU Kochen first reported the temperature history of China over the past “5000-year” based on phenological documents and pioneered the study of climate and dynasty transitions. Over the past few decades, many efforts have been made to reconstruct the climate records. Lack of high-resolution and climate records, especially for the heartland of ancient China, limits the comprehensive examination of the relationship between climate and culture changes.

A group of researchers from Nanjing Institute of Geography and Limnology of the Chinese Academy of Sciences (CAS), Institute of Tibetan Plateau Research of CAS, Nanjing University, and other institutions, presented well-dated, high resolution, warm-season temperature and annual mean precipitation records, and provided a high-quality climate background for the entire “5000-year” Chinese history. The study was published in Quaternary Science Reviews.

The researchers found that changes in temperature and precipitation are incomplete coupled in terms of long-term trend and centennial-scale variability before ~1000 CE (Common Era). The temperature displayed a slight decrease of ~0.5°C before ~200 CE and a rapid cooling of ~4°C afterwards, superimposed with four 1-2°C centennial-scale cold events. The precipitation showed high value before ~1000 BCE and a gradual decrease of ~250 mm with two distinct ~100 mm centennial scale dry intervals after ~1000 CE.

Comparing the records of climate changes and social factors, the researchers revealed that climate fluctuations likely played an important role in affecting cultural changes. Some centennial-scale cold and/or dry oscillations are often accompanied by an increase of war frequency, a sharp decline of population size and a southward migration of northern nomads.

Climate changes in dynastic China indicated that the Three Sovereigns and Five Emperors began in a relatively warm and wet climate, and the moderate conditions lasted until Shang Dynasty followed by a gradually cold and dry climate with large fluctuations afterward. Specifically, cold-dry condition was found in the late Tang, 5D&10K, late Song, Yuan, late Ming Dynasty, and only cold condition was found during SAWS and WJSN.

Three large-scale social unrests of the Spring and Autumn and Warring States (SAWS) periods, Wei, Jin and Southern and Northern Dynasties (WJSN) and Five Dynasties and Ten Kingdoms (5D&10K), and Yuan and Qing Dynasties when northern nomads ruled the central plains have experienced rapid climate changes.

Besides, the researchers found that dynasty transitions may also be influenced by other sociocultural factors and administrative efficiency such as class struggle and economic collapse. For example, the collapse of some dynasties such as Xia, Shang and Qin Dynasties occurred under a background of stable climate, and ~70 years of cold event at ~750 CE did not lead to the collapse of the prosperous Tang Dynasty although it likely corresponded to the famous An-Shi Rebellion.

Climate changes may not be a decisive factor of dynastic transitions despite their impacts on cultural changes. The high-resolution climate records in this study provide a crucial climate context to test the hypothesis that climate changes have impacts on culture changes.