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DURHAM, N.C. – Climate change, not ongoing regional conflict, was the cause of a severe dust storm that enveloped much of the Middle East and the Mediterranean last September, according to new research published this week in the peer-reviewed journal Environmental Research Letters.
The storm, labeled by some media outlets as the ‘Middle-Eastern Dust Bowl,’ affected Syria, Lebanon, Turkey and Cyprus, leading to scores of people being hospitalized, ports being closed, flights being cancelled, and large portions of the affected countries and eastern Mediterranean Sea being covered in an unprecedented haze.
Anthony Parolari, assistant professor of environmental engineering at Marquette University and a former postdoctoral research associate in civil and environmental engineering at Duke University’s Nicholas School of the Environment and Pratt School of Engineering, led the new study.
Gabriel G. Katul, the Theodore S. Coile Professor of Hydrology and Micrometeorology at Duke’s Nicholas School of the Environment, co-authored the study along with researchers at Boston University, Princeton University and Israel’s Institute of Soil, Water and Environmental Sciences.
At the time of the storm, several news stories blamed conflict-associated changes in regional land cover – including the widespread abandonment and reduced irrigation of agricultural lands and increased military vehicle traffic over unpaved surfaces – for the extreme dust and historic haze.
Parolari, Katul and their team, however, find that rare meteorological conditions, including extreme heat and drought, coupled with cyclonic winds typical in the region during late summer, were more likely the cause.
“The Middle East is a notable hotspot for dust storms during summer, and these are usually associated with the Shamal – winds from the north – and seasonal cyclones,” Parolari says. “We ran meteorological simulations that showed historically unprecedented aridity, or dryness, in the region during the summer of 2015 combined with these winds to play a key role in the severity of the storm.”
The extremely hot and dry conditions occurring in the region increased the amount of dust that could be eroded by the storm, he explains. An unusual wind reversal at low levels immediately followed the storm, picking up this eroded dust and spreading it west into the Mediterranean.
Studies of surface air temperature, humidity and wind speeds measured at the Har Kanaan weather station in northern Israel strengthened the team’s assessment, Parolari says. The studies showed that the summer of 2015 was among the driest and hottest in 20 years, including the period from 2007 to 2010 when the region was gripped with a long-term drought. This extreme heat and aridity led to soil becoming less cohesive, making it more likely for cyclonic winds to dislodge large dust particles and transport them long distances in the atmosphere.
Studies of vegetative cover in the region over the last 15 years also added weight to the team’s finding that climate, not conflict, was to blame. These studies revealed that despite the abandonment of some farmlands due to escalating military conflict, the extent of vegetative cover in 2015 was nearly double the region’s average from 2007 to 2010, and was also greater than the 2001-2007 pre-drought years in many areas. Areas experiencing recent vegetation decline were relatively scarce – meaning the abandonment of farmlands due to conflict was unlikely to be the reason for the massive dust plume.
“While climate, land use and conflict all remain key elements of a complex human-environment relationship that has been playing out in the Middle East as far back as 4000 years ago following the collapse of the Akkadian empire, the so-called ‘Middle-Eastern Dust Bowl,’ appears to be explained by climate, not conflict and abandonment of agricultural land,” Parolari says.