Background to Mid-Holocene Climatic Change in Anatolia and Adjacent Regions

Abstract

The Holocene climate of Anatolia is strongly seasonal. It has been modulated by the astronomic effects of global origin. Because of progressive shift of the orbital precession, the summer seasons have grown slightly cooler, with reduced convectional precipitation and thunderstorms while winter seasons are, at low elevations, milder and wetter. However, climatic cycles typically of about 208.5 and 514 years periodicity (of the latter, about 20 in 10,700 yr) appear to be influenced by the trajectories of the southern Jet Stream, which may swing north or south, either at times to the Black Sea latitudes, at others to the eastern Mediterranean. During its northern swings (warmer global cycles) there are often drought conditions in the south and in northern Syria and Mesopotamia. The Third Millennium BC cultural disasters appear to reflect droughts engendered by the extreme enhancement of the first effect by the shorter-term cycles of the second type. The special position and elevation of Anatolia goes back to its geologic history and plate-tectonic evolution, briefly reviewed here. Differential uplift of the interior with marine basins to the north, west and southwest create a unique climatological setting which has established the physical basis for the Pleistocene, Holocene and Subboreal events.