Volcanic eruptions may have triggered abrupt climate change contributing to the repeated collapse of Chinese dynasties over the past 2,000 years, according to a new study released today. [Thursday, 11 November 2021].
The study also illustrates how volcanic eruptions can have a profound impact on vulnerable or unstable regions and highlights the need to prepare for future eruptions.
The research, which combines historical evidence with polar ice core records of volcanic eruptions, was jointly conducted by historians and environmental scientists from Trinity College Dublin and Zhejiang University in China. It will be published today in Earth & Environment Communications, a new high-profile review of Nature Portfolio.
Scientists have identified explosive volcanic eruptions as one of the most important drivers of dramatic climate change, often triggering sudden cooling and drying that can cause death to livestock and damage to crops. However, our understanding of the role played by such abrupt climatic shocks in state or society collapse has been limited by the precision and accuracy of dating available historical and climatic evidence.
Dr Francis Ludlow, associate professor of medieval environmental history at Trinity, who jointly led the study, said:
âChina has a remarkably long and richly documented history of several reigning dynasties, including major world powers like the Tang dynasty, which collapsed in AD 907, or the Ming dynasty, which collapsed in 1644. With so many precisely dated collapses, we can look not just at individual cases of collapse that may or may not have followed climate change, but rather looking at many collapses simultaneously to see if there is a repeated pattern where a change occurs. climate was followed by a collapse. the change played a very minor role in the dynastic collapse, or whether it posed a systematic threat to these powerful and sophisticated societies. “
The study compared the dates of volcanic eruptions gleaned from measurements of sulphate ice cores deposited on polar ice caps with known dates from historical records of the Chinese dynastic collapse during the first two millennia of the era. common. This exercise found that 62 of the 68 dynastic collapses were closely preceded by at least one volcanic eruption.
John Matthews, postdoctoral fellow at the Trinity Center for Environmental Humanities and co-author of the article, explained:
âResearchers have identified many historical eruptions through sulphate deposits in polar ice, so we would expect some collapses to have been preceded by eruptions purely by chance. To convince us that we were seeing something significant , we analyzed the numbers and found that there would be only a 0.05% chance of seeing so many collapses preceded by so many eruptions if it had actually happened at random. a repeated link between volcanic eruptions and dynastic collapse. â
Some dynasties, the authors note, withstood many large eruptions before finally succumbing, suggesting that the role of volcanism in the collapse is far from straightforward, and that dynasties often withstood sudden climatic shocks, triggered by volcanoes.
To gain a better understanding, the researchers assessed the role of explosive volcanism in tandem with other sources of stress or instability that a dynasty might experience by examining levels of warfare prevailing in the decades leading up to the collapse. War was found to be high before most collapses, but the study also found a strong link between the magnitude of a volcanic climate shock and pre-existing stress levels.
âWe found that even a small volcanic eruption could help trigger a collapse when pre-existing instability was high. However, larger eruptions could trigger a collapse even when pre-existing instability was minimal. So, as always, the context history is essential to understanding how climate can impact a society.It is also clear that we should prepare for the impacts of the next great eruption – so far, in the twentieth and twenty-first centuries, the eruptions that we have known were minnows compared to some that these dynasties had to contend with.
Chaochao Gao, Associate Professor, Zhejiang University, China, who co-led the research, concluded: âThis study shows us how important it is to build a resilient society to deal with the natural hazards we face, which they are of volcanic or other origin. . “