Climate change was not to blame for the collapse of the Bronze Age

Scientists will have to find alternative explanations for a huge population collapse in Europe at the end of the Bronze Age as researchers prove definitively that climate change - commonly assumed to be responsible - could not have been the culprit.

Archaeologists and environmental scientists from the University of Bradford, University of Leeds, University College Cork, Ireland (UCC), and Queen's University Belfast have shown that the changes in climate that scientists believed to coincide with the fall in population in fact occurred at least two generations later.

Their results, published this week in Proceedings of the National Academy of Sciences, show that human activity starts to decline after 900BC, and falls rapidly after 800BC, indicating a . But the show that colder, didn't occur until around two generations later.

Fluctuations in levels of through time are reflected by the numbers of radiocarbon dates for a given period. The team used new statistical techniques to analyse more than 2000 radiocarbon dates, taken from hundreds of archaeological sites in Ireland, to pinpoint the precise dates that Europe's Bronze Age population collapse occurred.

The team then analysed past climate records from peat bogs in Ireland and compared the archaeological data to these climate records to see if the dates tallied. That information was then compared with evidence of climate change across NW Europe between 1200 and 500 BC.

"Our evidence shows definitively that the population decline in this period cannot have been caused by climate change," says Ian Armit, Professor of Archaeology at the University of Bradford, and lead author of the study.

Graeme Swindles, Associate Professor of Earth System Dynamics at the University of Leeds, added, "We found clear evidence for a rapid change in climate to much wetter conditions, which we were able to precisely pinpoint to 750BC using statistical methods."

According to Professor Armit, social and economic stress is more likely to be the cause of the sudden and widespread fall in numbers. Communities producing bronze needed to trade over very large distances to obtain copper and tin. Control of these networks enabled the growth of complex, hierarchical societies dominated by a warrior elite. As iron production took over, these networks collapsed, leading to widespread conflict and social collapse. It may be these unstable social conditions, rather than climate change, that led to the population collapse at the end of the Bronze Age.

According to Katharina Becker, Lecturer in the Department of Archaeology at UCC, the Late Bronze Age is usually seen as a time of plenty, in contrast to an impoverished Early Iron Age. "Our results show that the rich Bronze Age artefact record does not provide the full picture and that crisis began earlier than previously thought," she says.

"Although climate change was not directly responsible for the collapse it is likely that the poor climatic conditions would have affected farming," adds Professor Armit. "This would have been particularly difficult for vulnerable communities, preventing population recovery for several centuries."

The findings have significance for modern day climate change debates which, argues Professor Armit, are often too quick to link historical climate events with changes in population.

"The impact of climate change on humans is a huge concern today as we monitor rising temperatures globally," says Professor Armit.

"Often, in examining the past, we are inclined to link evidence of with evidence of population change. Actually, if you have high quality data and apply modern analytical techniques, you get a much clearer picture and start to see the real complexity of human/environment relationships in the past."

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Changing climate may have driven collapse of civilizations in Late Bronze Age

More information: "Rapid climate change did not cause population collapse at the end of the European Bronze Age", by Ian Armit, Graeme Swindles, Katharina Becker, Gill Plunkett and Maarten Blaauw, is published in Proceedings of the National Academy of Sciences in the week beginning 17 November 2014.
Citation: Climate change was not to blame for the collapse of the Bronze Age (2014, November 17) retrieved 16 October 2019 from
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Nov 17, 2014
The problem is that almost no one understand how evolutionary dynamics work! It is not the COLD temp the makes the difference, it is the COOLING temp that makes the difference. That is, if you have a period of warming and increasing moisture there will be strong population growth, low selection pressure, and high stability. Once the conditions flatten out, even when warm, the selection pressure increases as population growth becomes far more restricted. And when it BEGINS to cool, even if still warm by historical standards, food supplies will begin to decrease, forcing the standard tough-time combo of food shortage, malnutrition, starvation, warfare, infection and disease, along with mass migrations. Then, once the culling is complete, stability returns, even if the temps are rather cool by historical standards, with available resources matching population sizes. K.D. Koratsky explains this well in Living With Evolution or Dying Without It.

Nov 17, 2014
OK you can rule out climate change as the only culprit - but probable made the popolations more prone to a variety of diseases? - that long back It would be very difficult if not impossible to proove - around this time settlements formed around places where the ore could be found they used and to my knowledge trade was allready present and nothing unusuall - a combination of bad harvests with an unknown very contaguable disease hitting these more dense settlements similar to the bubonic plague in the middle ages could be an explanation - but very hard to proove I guess

Nov 18, 2014
Although climate change was not directly responsible for the collapse it is likely that the poor climatic conditions would have affected farming

And what exactly is "poor climatic conditions", if not cold weather.

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