Climate Change Contributed to the Fall of One of the Most Powerful Ancient Empires, Study Suggests

The Assyrian Empire was once one of the largest and most powerful empires of the ancient world—and now scientists believe that climate change played a part in its demise.

The final decades of the Assyrian Empire (912-609 BCE) were marked by political instability and conflict from inside and outside forces but, say researchers writing in Science Advances, this was preceded by a series of "megadroughts" during the 7th century BCE that caused a decline in citizens' way of life.

"[The Assyrian Empire] was by far the largest empire in the region up to that time, controlling much of the territory from the Persian Gulf to Cyprus," co-author Adam Schneider said in a statement.

"The Assyrians were basically like the Empire in Star Wars, they are the all-devouring machine."

Zayandeh Rud River
The Zayandeh Rud river in Isfahan in Iran, once the center of the Assyrian Empire. Researchers now think climate change contributed to the ancient empire's downfall. AFP PHOTO / ATTA KENARE/Getty

The research suggests that the fortunes of the Empire were closely tied to the climate—starting and prospering in a period of steady rainfall and plentiful harvests. In contrast, the seeds of its collapse appear to have been sown during a stretch of megadroughts that resulted in crop failures, food shortages and higher levels of conflict.

This is based on the analysis of drip water fossilized in stalagmites found in Kuna Ba Cave, Iraq. The chemical composition of the stalagmites—specifically, levels of carbon and oxygen—reveal what levels of precipitation were like at various points in history up to 2007 CE, enabling researchers to see how levels have changed with time.

The results suggest droughts that hit the Assyrian Empire started earlier than previously thought and followed the wettest period on record for the region. This is significant because, according to Schneider, the Assyrians were particularly vulnerable to the changing climate due to the geography of northern Iraq.

"The Tigris River is so deeply cut into the surrounding soil that you can't do large scale-irrigation there," he said. "That's why rainfall was so crucial to their lives."

The researchers' emphasis on climate differs from previous research that has stressed the contribution of "internal politico-economic conflicts, territorial overextension, and military defeat," the study's authors write. But it adds to a body of research that shows how changes to the climate can change the course of history.

The French Revolution of 1789 is one example, as it followed years of poor harvests and rising bread costs. According to The New Yorker, historians have also suggested the change in climate during the "mini ice age" was responsible for the rejigging of Europe's social order—essentially, because it affected the harvest and caused widespread civil unrest.

More recently, political scientists have asked if the conflict in Syria is actually a "climate war," linking a series of poor harvests between 2006 and 2010 to a rush of rural-to-urban migration and, ultimately, political conflict.

"In the case of Syria, there was a mass exodus of farming families from the worst drought-affected areas in the north of the country (the agricultural bread basket of Syria) to the nearby cities of Damascus, Hama and Aleppo," Darcy Thompson, PhD Candidate, Political Science/Middle Eastern Studies, and Lina Eklund, Post Doctoral Researcher in Physical Geography/Middle Eastern Studies, both at Lund University, Sweden, wrote in a piece for The Conversation.

"However, what role this migration played in helping to fuel the uprisings and then the conflict is far from clear."