Volcanic eruptions contributed to the collapse of dynasties in China over the past 2,000 years by temporarily cooling the climate and affecting agriculture, according to a Rutgers University study.
Large eruptions create a cloud that blocks some sunlight for a year or two. That reduces the heating of the land in Asia in summer and causes a weaker monsoon and less rain, which reduces harvests.
We confirm for the first time that the collapses of dynasties in China during the last 2,000 years are more likely in the years after the volcanic eruptions said co-author Alan Robock, a professor in the School of Biological and Environmental Sciences at Rutgers University-New Brunswick. But the relationship is complex because if there are ongoing wars and conflicts, dynasties are more likely to collapse. The impact of colder weather on crops can also make conflict more likely, further increasing the likelihood of collapse .
Scientists reconstructed 156 explosive volcanic eruptions from the year 1 AD. until 1915 by examining elevated sulfate levels in ice cores from Greenland and Antarctica, according to the study published in the journal Communications Earth &Environment . The scientists also analyzed historical documents from China on 68 dynasties and examined warfare in China between 850 and 1911.
Erupting volcanoes can pump millions of tons of sulfur dioxide into the upper atmosphere, forming vast clouds of sulfuric acid that reflect sunlight and lower the Earth's average surface temperature.
Large eruptions can cause a double jeopardy of stark cold and dryness during the agricultural growing season says the study. The effects can be compounded by livestock deaths, accelerated land degradation, and increased crop damage from agricultural pests that survive during milder winters.
Scientists found that small jolts Volcanic climates can cause dynasties to collapse when political and socioeconomic tension is already high. Larger shocks can cause collapse without substantial prior stress. Other factors are lack of leadership, administrative corruption, and demographic pressures.
The mandate of heaven , an influential Chinese concept, allowed for some continuity between dynasties. The elites and the commoners they more readily accepted a new dynasty which, by taking power, demonstrated a divine mandate to rule that the previous dynasty had lost.
The scientists' findings underscore the need to prepare for future eruptions, especially in regions with economically vulnerable populations (perhaps comparable to the Ming and Tang dynasties in China) and/or that have a history of resource mismanagement, such as in Syria. before the 2011 uprising which may have been caused in part by drought.
The eruptions of the 20th and 21st centuries have been smaller than those of imperial China. Still, moderate eruptions may have contributed to the Sahelian drought of the 1970s to 1990s, which contributed to an estimated 250,000 deaths and caused 10 million refugees in this economically marginalized region. Future major eruptions, combined with climate change, are likely to profoundly affect agriculture in some of the most populated and marginalized regions on Earth, according to the study.