Climate change may have triggered past dark ages
Study says centuries-long cold droughts caused famine, wars and fall of Mediterranean societies
A cold, dry spell that lasted hundreds of years may have driven the collapse of eastern Mediterranean civilisations in the 13th century BC, researchers in France said.
In the Late Bronze Age, powerful kingdoms spanned lands that are now Egypt, Greece, Cyprus, Syria, Turkey, Israel and the Palestinian territories, but they collapsed suddenly around 1200BC.
Archeologists have long debated the reasons behind their fall, often citing economic factors. But in the past few years, more research has come to light indicating that natural factors, including a wintry drought, may have dried up agriculture, caused famine and brought about wars.
The latest findings, published in the open-access journal PLoS One, are based on an analysis of sediment from an ancient lake in southeastern Cyprus by lead researcher David Kaniewski of the University of Paul Sabatier in Toulouse.
Kaniewski found evidence of a 300-year drought beginning around 3,200 years ago in pollen grains derived from sediments of the Larnaca Salt Lake complex.
Changes in carbon isotopes and local plant species suggest that the series of four lakes were once a sea harbour at the heart of trade routes in the region, offering a new piece of the puzzle that suggests a history of environmental changes drove the region into a dark age.
"This climate shift caused crop failures, death and famine, which precipitated or hastened socio-economic crises and forced regional human migrations at the end of the Late Bronze Age in the Eastern Mediterranean and southwest Asia," the study said.
Other researchers have found related evidence of a climate shift in sea surface temperatures and a two degree Celsius drop around the same time in the northern hemisphere.
Just why these changes occurred remains a matter of open debate.
Some scientists suggest they may have been caused by a period of increased solar activity, which shifted the jet stream in the North Atlantic and led to drought by cooling the oceans and decreasing rainfall.
A similar climate event is believed to have happened in medieval times.
"The jury is still out on that one," said Lee Drake, an adjunct professor at the University of New Mexico whose own research has shown a drop in sea surface temperatures in the Mediterranean coincided with the Greek Dark Ages in the same period.
"If sea surface temperatures drop, then less water evaporates and less water precipitates over land. This period of cooler temperatures seems to be consistent with the Greek Dark Ages of about 400 years," he said.
"If you can imagine this complex Greek civilisation sitting on top of a bucket, then climate came and kicked it out from under them, and there was really nothing that they could have done," he said.
Drake said it is still unclear why, if the temperature change was global, the Mediterranean responded so dramatically.
"[It's] important to understand because it is not inconceivable that it could happen again."