How climate change and long-term drought caused the collapse of Bronze Age civilizations

By Roberta Attanasio

About 3,200 years ago, many Bronze Age civilizations were thriving on the Eastern shore of the Mediterranean. “To the north lay the mighty Hittite empire; to the south, Egypt was thriving under the reign of the great Pharaoh Ramses II. Cyprus was a copper emporium. Greece basked in the opulence of its elite Mycenaean culture, and Ugarit was a bustling port city on the Syrian coast. In the land of Canaan, city states like Hazor and Megiddo flourished under Egyptian hegemony. Vibrant trade along the coast of the eastern Mediterranean connected it all.”

Within a relatively short period of time, however, these civilizations collapsed almost simultaneously. What caused this collapse? For many years, there was no clear answer—wars, pestilence and earthquakes were all considered potential culprits. Then, in 2013, a group of researchers showed that climate change and related long-term drought was responsible for the demise of Bronze Age civilizations between 1250 and 1100 BC. For their study, the researchers used high-resolution analysis of pollen grains taken from gray muddy sediment beneath the Sea of Galilee in North Israel and the western shore of the Dead Sea. They also used a robust chronology of radiocarbon dating to assess pollen counts at intervals of 40 years.

Israel Finkelstein, one of the study co-authors, said that in a short period of time the entire world of the Bronze Age crumbled as a result of climate change. The study used a unique combination of technological, archaeological, and historical analysis to provide a full picture of the environmental disaster.

Dafna Langgut, another study co-author, said: “Pollen is the most enduring organic material in nature. These particles tell us about the vegetation that grew in the vicinity of the lake in the past and therefore testify to the climatic conditions in the region.” She also said that pollen grains are best preserved in lakes and deserts and last thousands of years. Each plant produces its own distinct pollen form, like a fingerprint. Therefore, extracting and analyzing the pollen grains from each stratum allows researchers to identify the vegetation that grew in the area and to reconstruct climate changes.

The results showed a sharp decrease in the Late Bronze Age of Mediterranean trees like oaks, pines, and carobs, and a similar decline in the local cultivation of olive trees, which the experts interpret as the consequence of repeated periods of drought. The droughts were likely exacerbated by cold spells, causing famine and the movement of marauders from north to south. Indeed, the Late Bronze Age is recognized as a period when marauding bands known as the Sea Peoples raided coastal towns in the eastern Mediterranean, especially in Egypt.

Finkelstein explained that climate change can be seen as a sort of a ‘prime mover’ that initiated other processes. For example, groups of people in the northern regions were uprooted from their homes because of destruction of the agricultural output, and started moving in search of food. They could have pushed other groups to move by land and sea. This in turn caused destructions and disruption of the delicate trade system of the eastern Mediterranean.

The devastating period ended when rains returned, allowing recovery and resettlement of uprooted populations—eventually giving rise to the kingdoms of biblical times, including ancient Israel and Judah.

A 2013 editorial in The New York Times aptly points out that “The pollen findings from the Sea of Galilee are interesting in and of themselves, but now, in an era of intensifying drought in so many places, they require more attention as reminders of how vulnerable even the strongest human societies may be to natural forces.”

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