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History: Volcanoes helped trigger the fall of some of China’s most powerful dynasties, study claims

The collapse of some of Imperial China’s most powerful dynasties over the last 2,000 years may have been triggered in part by volcanic eruptions, a study found.

Eruptions — by releasing sunlight-reflecting sulphate aerosols into the atmosphere — can cool and dry climates, leading to livestock death and crop damage. 

Researchers led from Zhejiang University analysed historical atmospheric sulphate levels recorded in ice cores extracted from both Antarctic and Greenland.

From this, they were able to reconstruct 156 explosive volcanic eruptions that occurred around the world between 1–1915 AD.

They also analysed documents from China detailing the history of 68 dynasties from 850–1911 — using warfare as a proxy for political and socioeconomic stress.

The team found that large volcanic climate ‘shocks’ can trigger societal collapse, like the fall of the Min and Later Jin dynasties in the wake of the 939 Eldgjá eruption.

This fissure volcano in Iceland — the largest volcanic canyon in the world — erupted 4.3 cubic miles of magma and led to one of the coolest summers in 1500 years.

Meanwhile, smaller eruptions also appeared to help precipitate dynastic shifts at times when political and socioeconomic stress was already high.

The collapse of some of Imperial China’s most powerful dynasties over the last 2,000 years may have been triggered in part by volcanic eruptions, a study found. Pictured: the crater of Mount Mélébingóy (Mount Parker), whose eruption preceded the collapse of the Ming Dynasty

Eruptions ¿ by releasing sunlight-reflecting sulphate aerosols into the atmosphere ¿ can cool global climates, leading to livestock death and crop damage. Pictured: Zhu Youjian, the Chongzhen Emperor and the last ruler of the Ming Dynasty, which collapsed in the wake of both the 1641 eruption of Mount Mélébingóy and a period of societal unrest

Eruptions — by releasing sunlight-reflecting sulphate aerosols into the atmosphere — can cool global climates, leading to livestock death and crop damage. Pictured: Zhu Youjian, the Chongzhen Emperor and the last ruler of the Ming Dynasty, which collapsed in the wake of both the 1641 eruption of Mount Mélébingóy and a period of societal unrest

MANDATE OF HEAVEN 

The societal impacts of volcanism on China may have been exacerbated, the team said, by the Chinese political philosophy of the ‘Mandate of Heaven’.

In this doctrine, which was used to justify the reign of many an emperor or king, Tiān (heaven, which embodies the natural order and will of the universe) bestows a mandate to rule.

Legitimate rulers need not have been of noble birth — but instead merely needed to be seen to succeed. 

Were a leader otherthrown, this would be interpreted as a sign that they were unworthy and had lost the mandate.

However, times of poverty and natural disaster could also be taken as signs that Tiān judged the present ruler unjust and needing to be replaced.

On the flip side, the same philosophy may have helped restore social order after unrest, with new dynasties able to quickly claim legitimate rule as divinely sanctioned mandate holders.

Indeed, the researchers found that after each dynastic collapse, warfare levels tended to fall rapidly. 

The study was undertaken by environmental scientist Chaochao Gao of China’s Zhejiang University and her colleagues. 

‘Sophisticated agronomy was critical to sustain successive populous Chinese dynasties,’ the researchers explained in their paper.

Given this, they added, ‘abrupt climatic change and extreme weather thus held the potential to deeply perturb their political, economic and demographic functioning,

‘Volcanic eruptions are one of the most important drivers of sudden and pronounced short-term climatic variability.

‘In addition to pronounced summer cooling from aerosol scattering of incoming solar radiation, volcanic aerosols can reduce evaporation over water bodies and affect the seasonal migration of the intertropical convergence zone, promoting weakened summer monsoons,’ the team continued.

‘Major eruptions can thus introduce a double jeopardy of marked coldness and drought during the agricultural growing season.

‘The resulting impacts may be compounded by livestock death, accelerated land degradation, and additional crop damage from the survival of agricultural pests during regionally mild winters [that can result from tropical volcanism].’

From their analysis, the team concluded that 62 out of the total of 68 dynastic collapses were closely preceded by at least one volcanic eruption somewhere around the globe.

However, paper author John Matthews of Trinity College Dublin caution, the team ‘identified a lot of historical eruptions […] so we expect that some collapses will have been preceded by eruptions purely by chance.

‘To convince ourselves we were seeing something significant, we ran the numbers and found there would be just a 0.05 per cent chance of seeing so many collapses preceded by so many eruptions if that had actually happened randomly.

‘This study shows a repeated link between volcanic eruptions and dynastic collapse.’

The researchers noted, however, that the relationship is likely highly complex, and that Imperial China was often resilient against climate shocks, with many dynasties surviving numerous large eruptions before eventually succumbing.

For example, the most powerful eruption in recorded history — the 1815 explosion of Mount Tambora in Indonesia — did not bring down the contemporaneous Qing Dynasty, which continued to rule the country for almost another century.

The team specifically found a strong link between the magnitude of a volcanic climate shock’s effect on China and the level of pre-existing unrest, as measured in terms of warfare levels. 

‘We found that even a small volcanic eruption might help trigger a collapse when pre-existing instability was high. Larger eruptions, however, could trigger a collapse even when pre-existing instability was minimal, Dr Matthews explained.

‘As ever, historical context is key to understanding how climate can impact a society.’

The team found that large volcanic climate 'shocks' can trigger societal collapse, like the fall of the Min and Later Jin dynasties in the wake of the 939 Eldgjá eruption . This fissure volcano in Iceland (pictured) ¿ the largest volcanic canyon in the world ¿ erupted 4.3 cubic miles of magma and led to one of the coolest summers in 1500 years

The team found that large volcanic climate ‘shocks’ can trigger societal collapse, like the fall of the Min and Later Jin dynasties in the wake of the 939 Eldgjá eruption . This fissure volcano in Iceland (pictured) — the largest volcanic canyon in the world — erupted 4.3 cubic miles of magma and led to one of the coolest summers in 1500 years

‘We confirmed for the first time that collapses of dynasties in China over the last 2,000 years are more likely in the years after volcanic eruptions,’ said paper author and climatologist Alan Robock of the Rutgers University-New Brunswick.

‘But the relationship is complex because if there is ongoing warfare and conflict, dynasties are more susceptible to collapse.

‘The impact of a cooled climate on crops can also make conflict more likely, further increasing the probability of collapse.’ 

The researchers noted that Imperial China was often resilient against climate shocks, with many dynasties surviving numerous large eruptions before eventually succumbing. For example, the most powerful eruption in recorded history ¿ the 1815 explosion of Mount Tambora in Indonesia (depicted) ¿ did not bring down the contemporaneous Qing Dynasty, which continued to rule the country for almost another century

The researchers noted that Imperial China was often resilient against climate shocks, with many dynasties surviving numerous large eruptions before eventually succumbing. For example, the most powerful eruption in recorded history — the 1815 explosion of Mount Tambora in Indonesia (depicted) — did not bring down the contemporaneous Qing Dynasty, which continued to rule the country for almost another century

‘This study tells us how important it is to build a resilient society to cope with the natural hazards that we face, be they volcanically-induced or otherwise.’ Professor Gao cautioned.

We have been lucky in the 20th and 21st centuries in that recent volcanic eruptions have been smaller than those that occurred during China’s Imperial period. 

However, the researchers noted, moderate volcanic eruptions are thought to have contributed to the Sahelian drought of the 1970s–1990s, which are estimated to have led to some 250,000 deaths and resulted in 10 million refugees.

The combination of future volcanism and climate change, the study warned, is likely to profoundly affect agriculture in some of the Earth’s most populated and marginalised regions. 

The full findings of the study were published in the journal Communications Earth & Environment.

HOW CAN RESEARCHERS PREDICT VOLCANIC ERUPTIONS?

According to Eric Dunham, an associate professor of Stanford University’s School of Earth, energy and Environmental Sciences, ‘Volcanoes are complicated and there is currently no universally applicable means of predicting eruption. In all likelihood, there never will be.’

However, there are indicators of increased volcanic activity, which researchers can use to help predict volcanic eruptions. 

Researchers can track indicators such as: 

  • Volcanic infrasound: When the lava lake rises up in the crater of an open vent volcano, a sign of a potential eruption, the pitch or frequency of the sounds generated by the magma tends to increase.
  • Seismic activity: Ahead of an eruption, seismic activity in the form of small earthquakes and tremors almost always increases as magma moves through the volcano’s ‘plumbing system’.
  • Gas emissions: As magma nears the surface and pressure decreases, gases escape. Sulfur dioxide is one of the main components of volcanic gases, and increasing amounts of it are a sign of increasing amounts of magma near the surface of a volcano. 
  • Ground deformation: Changes to a volcano’s ground surface (volcano deformation) appear as swelling, sinking, or cracking, which can be caused by magma, gas, or other fluids (usually water) moving underground or by movements in the Earth’s crust due to motion along fault lines. Swelling of a volcano cans signal that magma has accumulated near the surface.  

Source: United States Geological Survey

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