The Scenario of Environmental Degradation in the Tell Leilan Region, Ne Syria, During the Late Third Millennium Abrupt Climate Change

Abstract

This paper refines the characterization of the 2200-1900 BC abrupt climate change identified within soil proxy data retrieved on the Habur Plains (N.E. Syria), We compare a selection of soil stratigraphic data from: (1) archaeological contexts in which abandonment sequences above the last Tell Leilan period IIb (2300-2200 B.C.) occupation floors provide a continuous record of the depositional dynamics 3200-1900 BC; (2) natural soil contexts in the environs of Tell Leilan that parallel the local site record with changes of soil-forming conditions and landform dynamics at a micro-regional level. An interpretive model is elaborated to define the environmental variables involved in the dynamic behavior of regional soil systems, Soil a,tributes produced by redistribution of calcium carbonate, biological activity, movements of solid particles at the soil surface and through the soil, wetting-drying cycles, and wind activity, are all examined. The soil record of the abrupt climate change reveals a weakening of pedological transformations. an increase of surface crusting and wind intensity, and an aerosol fallout rich in glass shards and calcitic spherules. These features characterize an aridification event unique in comparison to the other environmental changes recorded over the last 8000 years on the Habur Plains. These changes are both greater and different in nature than the effects of the droughts common to the region's semi-arid Mediterranean climate. The soil degradation differs from the shortterm fragilization of soil equilibrium induced by the abandonment of cultivation and land management. The increase of atmospheric dust loading rapidly initiated the hostile environmental conditions that constrained and reduced late third millennium intensified agro-production in North Mesopotamia, and thereby forced the collapse of Akkadian agro-imperialism. General circulation model linkages suggest both the spatial extent and the regional variability of the 2200-1900 BC abrupt climate change.