Special to UM News

UM Rosenstiel researchers uncover the effects of climate on human societies 

Professor Ali Pourmand (right) and Ph.D. candidate Arash Sharifi inspect the physical properties of a meter-long sediment core collected from northwest Iran that recorded the environmental conditions in the region  for the past 2,000 years.

MIAMI, Fla. (July 28,2015)—New research reveals that some of the earliest civilizations in the Middle East and the Fertile Crescent may have been affected by abrupt climate change. The findings show that, while socio-economic factors have long been considered to have shaped 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 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 compared to the latter 6,000 years, when 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 is attributed to higher solar insolation during this period,” said 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.”

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,” said Arash Sharifi, Ph.D. candidate in the Department of Marine Geosciences and 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.”

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.

Funded by the National Science Foundation, the study, “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?” will be published in the September 1 issue of the journal Quaternary Science Reviews, and is currently available online.

In addition to Sharifi and Pourmand, the study coauthors include Larry C. Peterson and Peter K. Swart, of the Rosenstiel School; Elizabeth A. Canuel and Erin Ferer-Tyler, of the Virginia Institute of Marine Science, College of William and Mary; Bernhard Aichner and 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; and Abdolmajid Naderi Beni and Hamid A.K. Lahijani, of the Iranian National Institute of Oceanography and Atmospheric Science.