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Ancient climate clues shed new light on history

This story originally appeared on Yale Environment 360 and is part of the Climate office collaboration.

Joseph Manning, professor of ancient history at Yale University, likes to recall the moment he was shown an advance copy of a scientific paper that identified the timing of major volcanic eruptions over the past 2,500 years. Reading the newspaper, “I literally fell out of my chair,” he said recently..

Using new geochemical techniques for analyzing ice core sediments to determine dates of ancient volcanic activity down to the year or even season, the paper, Posted in Nature in 2015 showed that major eruptions around the world cause dizzying rainfall that can last up to a decade drop in global temperatures. Further research fixed these drops down to 13 degrees F.

What amazed Manning, an Egyptologist, was that the paper recalibrated earlier timelines from seven to eight years so that the dates of the eruptions coincided perfectly with the timing of the well-documented political, social and military upheavals over three centuries of ancient Egyptian history. The document also correlated volcanic eruptions with the 6 majorand pandemics, famines and socio-economic turmoil of the century AD in Europe, Asia and Central America. The inescapable conclusion, according to the article, was that volcanic soot – which cools the earth by shielding its surface from sunlight, negatively affecting growing seasons and causing crop failures – helped fuel these crises.

Since then, other scientific papers drawing on paleoclimate data — most relying on cutting-edge technologies originally designed to understand climate change — have found countless instances where climate change has contributed to trigger social and political upheavals and, often, collapses. . The latest is a paper published last month in Earth and Environment Communications which posits “a systematic association between volcanic eruptions and dynastic collapse across two millennia of Chinese history”.

The study found that 62 out of 68 dynastic collapses occurred shortly after the Northern Hemisphere volcanic eruptions, an outcome that had only a 1 in 2,000 chance of occurring if the eruptions and collapses were unrelated. The Chinese have traditionally cited the withdrawal of the “Mandate of Heaven” to explain the cold weather, droughts, floods and agricultural failures that seemed to accompany the fall of dynasties. The article argues that these phenomena have a climatic explanation.

All of these articles are propelled by a nearly decade-long revolution in climate science technology. A blizzard of quantitative data from “climate proxies” – ice cores, tree rings, stalagmites and stalactites from caves, and sediments from lakes, bogs and seabeds – has upended the way some historians do their work.

Joe McConnell, who leads a pioneer ice core analysis laboratory of the Desert Research Institute in Reno, Nevada, believes that climate data offers historians what DNA evidence provides to the legal system: an objective and indisputable source of critically important information. Like DNA evidence that overturns a guilty verdict, McConnell said, climate data is information that historians “must integrate.”

To exploit this data, some historians cross vast barriers within their discipline to work with biologists, geologists, geographers, paleoclimatologists, climate modellers, anthropologists and others. These pioneering historians learn geochemistry and climatology; the scientists they work with read history.

Ancient climate clues shed new light on history

Source link Ancient climate clues shed new light on history

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