Climate variability in the Aral Sea basin (Central Asia) during the late Holocene based on vegetation changes |
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| Authors: | Philippe Sorrel Speranta-Maria Popescu Stefan Klotz Jean-Pierre Suc Hedi Oberhnsli |
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| Institution: | aGeoForschungsZentrum Potsdam, Telegraphenberg, D-14473 Potsdam, Germany;bLaboratoire PaléoEnvironnements et PaléobioSphère (UMR 5125 CNRS), Université Claude Bernard-Lyon 1, 27–43 boulevard du 11 Novembre, F-69622 Villeurbanne Cedex, France;cInstitut für Geowissenschaften, Universität Tübingen, Sigwartstrasse 10, D-72070 Tübingen, Germany |
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| Abstract: | High-resolution pollen analyses ( 50 yr) from sediment cores retrieved at Chernyshov Bay in the NW Large Aral Sea record shifts in vegetational development from subdesertic to steppe vegetation in the Aral Sea basin during the late Holocene. Using pollen data to quantify climatic parameters, we reconstruct and date for the first time significant changes in moisture conditions in Central Asia during the past 2000 yr. Cold and arid conditions prevailed between ca. AD 0 and 400, AD 900 and 1150, and AD 1500 and 1650 with the extension of xeric vegetation dominated by steppe elements. These intervals are characterized by low winter and summer mean temperatures and low mean annual precipitation (Pmm < 250 mm/yr). Conversely, the most suitable climate conditions occurred between ca. AD 400 and 900, and AD 1150 and 1450, when steppe vegetation was enriched by plants requiring moister conditions (Pmm 250–500 mm/yr) and some trees developed. Our results are fairly consistent with other late Holocene records from the eastern Mediterranean region and the Middle East, showing that regional rainfall in Central Asia is predominantly controlled by the eastern Mediterranean cyclonic system when the North Atlantic Oscillation (NAO) is in a negative phase. |
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| Keywords: | Pollen analysis Vegetation Climate Aral Sea Late Holocene Central Asia Negative NAO |
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