Archaeologists have debated for decades over what caused the once-flourishing civilizations along the eastern Mediterranean coast to collapse about 1200 BC. Many scholars have cited warfare, political unrest and natural disaster as factors. But a new study supports the theory that climate change was largely responsible.
Analyzing ancient pollen grains from Cyprus, researchers concluded that a massive drought hit the region about 3,200 years ago. Ancient writings have described crop failures, famines and invasions about the same time, suggesting that the drying trend triggered a chain of events that led to widespread societal collapse of these Late Bronze Age civilizations.
Before their downfall, the Aegeans, Hittites, Egyptians and Syro-Palestinians had formed a complex, economically linked network in the eastern Mediterranean. But about 1200 BC, they "disappeared completely from history," said Lee Drake, an archaeologist at the University of New Mexico who was not involved in the study.
What led to the large-scale demise of these civilizations has remained "one of the mysteries of the ancient world," researchers wrote in the journal PLOS One on Wednesday. Archaeologists have proposed several theories, including climate change. But these relied mainly on ancient texts and art.
Recent technological advances have allowed archaeologists to put the climate change theory to the test. In the new study, researchers were able to assemble a record of rainfall for the eastern Mediterranean dating back about 3,500 years.
Researchers first drilled a core about 27 feet long from the bed of the Larnaca Salt Lake on the island of Cyprus — a major center of ancient eastern Mediterranean trade — and used radiocarbon dating to determine the age of each sediment layer.
Then they examined the 84 pollen grains preserved within the core. They identified the tree species each grain came from, producing a time line of the vegetation cover in the region.
They found that lush woodlands gave way to arid grasslands about 3,200 years ago, marking one of "the driest [periods] of the last 5,000 years in the eastern Mediterranean region," said Joel Guiot, a paleoclimatologist at Aix-Marseille University in France and a study coauthor.
Analysis of marine fossils in the core revealed that the site was once a bustling harbor that eventually dried into a landlocked salt lake, probably disrupting trade and farming. Researchers also recovered less charcoal in more recent sediments, indicating less fire building and, it would stand to reason, fewer people.
Their findings closely match archaeological evidence of the collapse of civilizations in the region. The last trace of Late Bronze Age artifacts dates to the same time as the climate shift, while hieroglyphs and cuneiform texts describe famines and waves of mysterious "sea people" raiding Egypt, Turkey, Syria and Palestine’s shores about the same time. Archaeologists can now conclude they were probably eastern Mediterraneans fleeing their inhospitable homelands, seeking new areas to settle.
By combining environmental and archaeological data, the study marks "the first time we have anything resembling a crime scene investigation in archeology," Drake said. "Climate has been caught red-handed."
He added, "We tend to focus on political, human-driven problems, but there isn’t a human driver for the destruction that matches what happened 3,000 years ago."
The study serves as a reminder for current generations to address climate change, especially in the Mediterranean, Guiot said.
"Mediterranean agriculture is dependent on climate," he said. "In the past, precipitation deficits have produced civilization declines. Strong famine remains possible in the future in these vulnerable regions."
[For the record, 10:02 p.m. Aug. 16: An earlier version of this post said that once-flourishing civilizations along the eastern Mediterranean coast collapsed about 1300 BC. The time was about 1200 BC.]