In a new research study an international team of geoscientists reconstructed the history of Saharan dust storms during the last 12,000 years. The researchers identified several millennial-scale phases of enhanced Saharan dust supplies during the transition of the former “green Sahara” to the present-day hyper-arid desert. Research indicates that contrary to earlier belief, the formation of the desert was not caused by a single climatic event, but rather by multiple millennial-scale dust phases.
The results were recently published in the prestigious geoscientific journal Quaternary Science Reviews. The team was under the direction of Dr. Christoph Zielhofer - Physical Geographer at Leipzig University in Germany With him on the team were geographers, geoscientists, meteorologists, and archaeologists from Germany, The United Kingdom and Iceland, including Steffen Mischke, professor at the University of Iceland's Faculty of Earth Sciences.
The Sahara is not only the world's largest desert but also the largest source of sandstorms in the world. The Sahara is the world's largest desert and dust source with significant impacts on trans-Atlantic terrestrial and large-scale marine ecosystems. Remote Saharan dust influences the earth's radiation budget and tropical North Atlantic ocean-atmosphere temperature variability. The Sahara might thus even attenuate Hurricane activity.
In earlier times the Saharan region was characterised by dry steppe and savannahs with elephants, lions and a large number of animals. The last 12,000 years of Saharan history comprises the end of the so-called African Humid Period. This transition toward the present-day hyper-arid desert took place approximately 3,000 to 7,000 years before present time according to current science.
By the investigation of recovered cores from Lake Sidi Ali in the Moroccan Middle Atlas, the research team traced back Saharan dust phases until a time of 12,000 years before present. The research team's results indicate that the periods of sandstorms, that span millennia, have swept the area during the period that it changed from the former "green Sahara" to the present-day hyper-arid desert. These changes must have had severe consequences for former vegetation cover, wildlife and humans.
The researchers were surprised to discover that the end of the African Humid Period was not characterised by a single climatic transition toward a drier stage as formerly assumed, but by multiple millennial-scale dust phases. The most prominent took place at approximately 10,200, 8,200, and 6,600 to 6,000 years before present, interrupted by phases of low dust supply. The latest at 4,700 years before present the atmospheric dust load was comparable to current climatic conditions.
