2,000-yr climate record reveals hidden story of Tibetan Empire

Researchers at the Chinese Academy of Sciences have led a groundbreaking study, unveiling new insights into the rise and fall of the Tibetan Empire. The research team obtained climate records spanning more than 2,000 years using varvado sediments from Lake Jiangko on the central Tibetan plateau.

The findings, published in the prestigious Science Bulletin, shed light on the link between climate change and the rise and decline of this ancient empire.

Uncovering Tibetan Plateau's Ancient Sediments

The researchers conducted extensive investigations in the Tibetan Plateau area and discovered remarkably well-preserved sediments in Jiangko Lake. Using advanced dating methods such as varve counting and radiometric dating, they accurately determined a 2,000-year time range from a gravity core, which was up to a meter wide.

To further unravel the climate story, the team performed a high-resolution XRF elemental scan and analyzed isotopes of carbonate, carbon, and oxygen found in the sediment. Biomarkers such as alkenones were used to reconstruct temperature and precipitation records spanning the last two millennia. The results revealed an exceptional period of heat and humidity during the 7th to 9th centuries AD.

Surprisingly, this hot and humid era coincided precisely with the height of the power of the Tibetan Empire. The researchers compared their findings with historical literature and found a strong correlation between climate changes and changes in the empire's foreign policy.

Climate Change Shapes Tibetan Civilization

The research team used the ecological niche model to simulate the extent of barley cultivation during the warm and humid period from the 7th to the 9th century AD. Surprisingly, the researchers discovered a large difference of around 10.88 million hectares in cultivated area compared to the cold, dry period that followed.

Since the Tibetan Plateau has an ecologically fragile environment, climate change is considered one of the key factors influencing human activities in the region. The study highlights that the hot and humid climate favored the expansion of agriculture and livestock in the highlands, while the cold and dry conditions had adverse effects on these activities.

The researchers emphasized the importance of studying past human-environment interactions in light of the ongoing warming and humidification of the Tibetan Plateau. Understanding the historical impacts of climate change can inform modern responses to environmental changes.

During the 7th to 9th centuries, the Tibetan Empire emerged as a powerful superpower, encompassing vast territories and playing a crucial role in geopolitics across Asia during the early medieval period. The factors that contributed to the rise of the empire and its subsequent rapid decline remained ambiguous. While previous historical accounts focused on the leadership of Tibetan kings and religious conflicts, this research highlights the importance of climate change in shaping the fate of the empire.

Ancient civilizations, Climate lessons ahead

This study represents a fundamental step towards understanding the intertwined relationship between climate dynamics and ancient civilizations. The findings are a testament to the vulnerability of human societies to environmental changes and provide valuable lessons for managing current and future climate changes.

As the Tibetan Plateau continues to experience rising temperatures and higher humidity, the importance of these historical findings extends beyond academic interest and affects sustainable practices and agricultural development in the region.

As the researchers continue their groundbreaking work, they hope to reveal more information about the delicate balance between human activities and the environment and pave the way for more informed decisions in the face of ongoing climate challenges.

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