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.