Climate’s Impact Through the Ages

Some of the earliest civilizations in the Middle East and the Fertile Crescent may have been affected by abrupt climate change, a study by researchers has found.

These findings show that while socio-economic factors were traditionally considered to shape ancient human societies in this region, the influence of abrupt climate change should not be underestimated.

A team of international scientists led by researchers from the University of Miami's Rosenstiel School of Marine and Atmospheric Science found that during the first half of the last interglacial period known as the Holocene epoch, which began about 12,000 years ago and continues today, the Middle East most likely experienced wetter conditions in comparison with the last 6,000 years, when the conditions were drier and dustier.

"Evidence for wet early Holocene was previously found in the Eastern Mediterranean Sea region, North and East African lakes and cave deposits from Southwest Asia, and attributed to higher solar insolation during this period," says Ali Pourmand, assistant professor of marine geosciences at the Rosenstiel School, who supervised the project.

"Our study, however, is the first of its kind from the interior of West Asia and unique in its resolution and multi-proxy approach," he notes.

The Fertile Crescent, a region in west Asia that extends from Iran and the Arabian Peninsula to the eastern Mediterranean Sea and northern Egypt, is one of the most climatically dynamic regions in the world and is widely considered the birthplace of early human civilizations.

"The high resolution nature of this record afforded us the rare opportunity to examine the influence of abrupt climate change on early human societies," says Arash Sharifi, a graduate student in the department of marine geosciences and the lead author of the study.

"We see that transitions in several major civilizations across this region, as evidenced by the available historical and archeological records, coincided with episodes of high atmospheric dust; higher fluxes of dust are attributed to drier conditions across the region over the last 5,000 years," he says.

The researchers investigated climate variability and changes in paleoenvironmental conditions during the last 13,000 years based on a high-resolution (sub-decadal to centennial) peat record from Neor Lake in Northwest Iran. Abrupt climate changes occur in the span of years to decades.

This study is titled "Abrupt climate variability since the last deglaciation based on a high-resolution, multi-proxy peat record from NW Iran: The hand that rocked the Cradle of Civilization?" The paper, published in the journal of Quaternary Science Reviews, is available online.

The study's authors include: Arash Sharifi, Ali Pourmand, Larry C. Peterson, and Peter K. Swart of UM's Rosenstiel School; Elizabeth A. Canuel, Erin Ferer-Tyler of the Virginia Institute of Marine Science, College of William and Mary; Bernhard Aichner, Sarah J. Feakins of the University of Southern California; Touraj Daryaee of the University of California, Irvine; Morteza Djamali of the Institut Méditerranéen de Biodiversité et d'Ecologie, France; Abdolmajid Naderi Beni, and Hamid A.K. Lahijani of the Iranian National Institute of Oceanography and Atmospheric Science, Iran.

- Rosenstiel School