Explosive eruptions triggered climate changes that doomed dynasties as crops and livestock failed, says study.
Explosive eruptions triggered climate changes that doomed dynasties as crops and livestock failed, says study.
Over the last 2,000 years, volcanic eruptions may have triggered changes in climate that contributed to China’s ruling dynasties ending, researchers have determined.
A new study published in the journal Communications Earth & Environment “shows a repeated link between volcanic eruptions and dynastic collapse,” co-author John Matthews said, and suggests the modern world is vulnerable to future eruptions.
Researchers compared records of polar ice cores with historical evidence. Volcanism has been tagged by scientists as an important factor in sudden climate change, such as cooler and drier weather that cause crop failures and mass livestock death. Until now, the role of these climate shocks has not been entirely understood because of the limited accuracy of historical records and climate evidence.
“China has a remarkably long and richly documented history of multiple ruling dynasties, including major world powers like the Tang Dynasty, which collapsed in 907 A.D., or the Ming Dynasty, which collapsed in 1644,” study co-author Francis Ludlow said.
The researchers delved into Chinese records that gave precise dates of collapses, allowing them to examine individual cases that may or may not have been preceded by climate change. According to Ludlow, this allowed the research team to “look simultaneously at many collapses to see whether there is a repeated pattern where a change in climate was followed by collapse.”
Measurements taken from ice cores of sulfate deposited in polar ice sheets provide dates of volcanic eruptions. These were compared with historical records of Chinese dynastic collapse over the last 2,000 years. The researchers found that of the 69 dynastic collapses recorded, 62 were closely preceded by at least one volcanic eruption.
Study co-author John Matthews said that while researchers have linked many eruptions to historical records, the ruin of some dynasties may have been preceded by volcanism merely by chance. To test their data, Matthews said “we ran the numbers and found there would be just a 0.05 percent chance of seeing so many collapses preceded by so many eruptions if that had actually happened randomly.”
The authors cautioned that some dynasties could withstand multiple large eruptions before their eventual collapse, which means that the link between eruptions and dynastic end-times is far from a given. The team looked at the role played by explosive volcanism when combined with other sources of instability, such as war. They found, for example, that warfare was prominent before dynastic collapse, but the study also revealed a strong link between the level of climatic shock caused by volcanism and the level of pre-eruption sources of stress.
“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. So as ever, historical context is key to understanding how climate can impact a society,” said study co-author Chaochao Gao. She said societies should prepare for the “next big eruption,” noting that the eruptions of the 20th and 21st centuries were small in comparison to those of previous centuries.
Edited by Richard Pretorius and Kristen Butler
