Volcanic mountains

Volcanic eruptions contributed to repeated collapse of ancient Chinese dynasties, new study finds

One or more volcanic eruptions preceded the majority (62 out of 68) of dynastic collapses in China over the past 2,000 years, according to new research by scientists from Zhejiang University and Trinity College Dublin.

Tang dynasty mural commemorating General Zhang Yichao’s victory over the Tibetans in 848 CE, from Cave 156 in Mogao.

“China’s long history therefore presents an unparalleled opportunity to examine whether abrupt climate change has a role in the recurrent and precisely datable collapse of 68 dynasties during the first two millennia of our era,” said the first author. , Dr. Chaochao Gao of Zhejiang University and his colleagues.

“The fall of these dynasties is often described in terms of ‘collapse’.”

“Some have certainly occurred with apparent rapidity in the context of intense conflict and with the significant agro-ecological and socio-economic disruptions and population loss that are important components in many cases and definitions of collapse, but others have occurred as less disruptive transitions between ruling families and elites, with considerable bureaucratic and economic continuities.

“These events have also been historically placed in the context of a ‘dynastic cycle’, in which dynasties passed through a period of virtue and vigor before decline and collapse, often traditionally attributed to immorality and the corruption of the ruling family and elites.”

“Socio-economic and demographic pressures, mass migration and displacement of people, as well as mismanagement of natural resources and environmental degradation, are now more often highlighted as causal factors.”

“The contribution of climatic stresses also began to assume increased – though often controversial – importance, for example with the collapse of the Tang dynasty in 907 CE, the Yuan dynasty in 1368 CE and the Ming dynasty in 1644 CE linked to episodes of drought and cold.

“Explosive volcanism has also been proposed as an underlying climate forcing associated with specific individual collapses, but the extent to which these observations are generalizable to the broader multi-millennial history of dynastic collapse, with explosive volcanism – and an abrupt climate change by extension – playing a systematic role, has never been established.

Chinese Dynastic Collapse, Explosive Volcanism, and War Frequency, 1-1911 CE: Consensus dates for 68 Dynastic Collapses (vertical blue dashed columns), overlaid with dates based on ice cores and inferred explosive climate forcing potential tropical and extratropical Northern Hemisphere volcanic eruptions (n=156) as inferred by multi-ice-core measurements of polar sulfate deposition (graded red circles), for 1-1911 CE.  The annual war frequency from 850 to 1911 CE (solid tan line) is also shown, with the thick brown line representing a 10-year smoothing using the Savitzky-Golay filter.  The figure is divided into two consecutive periods for visual clarity;  a and b respectively cover the first and second millennia of our era.  Image credit: Gao et al., doi: 10.1038/s43247-021-00284-7.

Chinese Dynastic Collapse, Explosive Volcanism, and War Frequency, 1-1911 CE: Consensus dates for 68 Dynastic Collapses (vertical blue dashed columns), overlaid with dates based on ice cores and inferred explosive climate forcing potential tropical and extratropical Northern Hemisphere volcanic eruptions (n=156) as inferred by multi-ice-core measurements of polar sulfate deposition (graded red circles), for 1-1911 CE. The annual war frequency from 850 to 1911 CE (solid tan line) is also shown, with the thick brown line representing a 10-year smoothing using the Savitzky-Golay filter. The figure is divided into two consecutive periods for visual clarity; a and b respectively cover the first and second millennia of our era. Image credit: Gao et al., doi: 10.1038/s43247-021-00284-7.

In their study, the scientists pieced together 156 explosive volcanic eruptions from 1 CE to 1915 by examining elevated sulfate levels in ice cores from Greenland and Antarctica.

They also analyzed historical documents from China on 68 dynasties and examined the war between 850 and 1911.

They found that smaller volcanic “shocks” on climate can cause dynasties to collapse when political and socio-economic stress is already high.

Larger shocks can lead to meltdowns without substantial pre-existing stress.

Other factors include poor leadership, administrative corruption and demographic pressures.

“With so many precisely dated collapses, we can not only look at individual cases of collapse that may or may not have followed climate change, but rather look at many collapses simultaneously to see if there is a repeating pattern where climate change climate change was followed by a collapse,” said co-lead author Dr Francis Ludlow, a researcher at Trinity College Dublin.

“This can tell us whether climate change played a very minor role in dynastic collapse, or whether it posed a systematic threat to these powerful and sophisticated societies.”

The authors found that 62 of 68 dynastic collapses in China were closely preceded by at least one volcanic eruption.

“We found that even a small volcanic eruption could help trigger a collapse when pre-existing instability was high,” said co-author Dr John Matthews, postdoctoral researcher at Trinity College Dublin.

“Larger eruptions, however, could trigger a collapse even when pre-existing instability was minimal.”

“So, as always, historical context is key 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 20th and 21st centuries the eruptions we have experienced have been minnows compared to some that these dynasties have had to to face. “

the to study appears in the newspaper Earth & Environment Communications.

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C. Gao et al. 2021. Volcanic climate impacts may act as ultimate and proximate causes of Chinese dynastic collapse. Common Earth Approximately 2.234; doi: 10.1038/s43247-021-00284-7