Volcanic Eruptions Hastened Collapse Of Chinese Dynasties

Volcanic eruptions helped collapse dynasties in China in the last 2,000 years by temporarily cooling the climate and affecting agriculture, a study published by Communications Earth & Environment found, Brian P. Dunleavy reported for United Press International (UPI).

Photo Insert: Wulanhada volcano, Inner Mongolia, China

Large eruptions created a cloud that blocked some sunlight for a year or two, reducing the warming of land in Asia in the summer and leading to weaker monsoons and less rainfall, the data showed.

This, in turn, led to decreases in crop harvests, causing hunger and migration that were factors in the collapse of several ruling dynasties in the region, the researchers said.

"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," co-author Alan Robock said.

"The impact of a cooled climate on crops can also make conflict more likely, further increasing the probability of collapse," said Robock, a professor of environmental sciences at Rutgers University in New Brunswick, New Jersey.

Erupting volcanoes can pump millions of tons of sulfur dioxide into the upper atmosphere, forming vast sulfuric acid clouds that reflect sunlight and lower the Earth's average surface temperature.

Major eruptions can lead to "a double jeopardy of marked coldness and dryness during the agricultural growing season," the researchers said. These impacts may be worsened by livestock deaths, accelerated land degradation, and more crop damage from agricultural pests that survive during milder winters.

For this study, Robock and his colleagues reconstructed 156 explosive volcanic eruptions from 1 A.D. to 1915 by examining elevated sulfate levels in ice cores from Greenland and the Antarctic.

They also analyzed historical documents on 68 Chinese dynasties and examined warfare in the region between 850 and 1911. Smaller volcanic "shocks" to the climate may have caused dynasties to collapse when political and socioeconomic stress is already high, the data showed.

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