Climate Change

Climate change has a history of disrupting civilisations, study finds

Major shifts in temperature and rainfall in the first millennium affected agriculture and also caused the decline of many indigenous groups in the Amazonia

By DTE Staff
Published: Tuesday 18 June 2019
Photo: Getty Images

Society and culture in the ancient Amazonia underwent a significant change as a result of the climate change that occurred in the first millennium, say researchers while cautioning against similar disruption that may take place in the future due to global warming.

From about AD 900 to 1250 (the Medieval Climate Anomaly) and 1450-1850 (the Little Ice Age), much of the Earth was impacted by major shifts in temperature and rainfall.

These changes affected agriculture and caused the decline of many indigenous groups in the Amazonia, according to the study published in the Nature Ecology and Evolution journal.

According to researchers, an estimated 8-10 million people lived in the Greater Amazon region, before the arrival of Europeans in 1492. 

While it was long thought that the advent of Europeans, marred by epidemics and violence, led to the decline of indigenous communities by 90-95 per cent, the study showed that climate also played a major role.

“This study adds to the growing evidence that the millennium preceding the European encounter was a period of long-distance migrations, conflict, disintegration of complex societies and social re-organisation across lowland South America. It shows the weather had a real impact,” said Jose Iriarte, professor at the University of Exeter.

Human activities that are presently causing rapid changes in weather patterns across the world can pose similar problems for many countries and also create “climate refugees”, which could cause great burden in the host countries, the researchers warned.

“So it’s kind of a one-two punch: if the climate doesn’t get you, it might be the thousands of bodies that show up that you have to feed because extreme drought forced them out of their homelands,” said Mitchell J Power, associate professor of geography at the University of Utah.

Further, the researchers found that societies that used intensive, specialised land-use systems were less able to cope with the climate change than others who relied on diverse food resources or polycultures and agroforestry.

For example, the pre-Columbian era society of Marajoara, from the Eastern Amazon, lived on large mounds. These mounds, which helped the communites to manage water, also made them sensitive to prolonged droughts. As a resut of the decreasing rainfall in the region, the mounds disintegrated after 1200.

On the other hand, the drier conditions had less impact on people in Santarém culture, that was established in around 1100.  They were more able to adapt because they grew a variety of crops — maize, sweet potato, squash — and also worked to enrich the forest, the study pointed out.

Further, as the climate became more volatile, the communities in the Amazon built canals to manage seasonal floods. They also fortified their ditches, walled plazas, causeways and roads.

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