Abrupt climate and vegetation variability of eastern Anatolia during the last glacial

Abstract

Abstract. Detailed analyses of the Lake Van pollen, Ca / K ratio, and stable oxygen isotope record allow the identification of millennial-scale vegetation and environmental changes in eastern Anatolia throughout the last glacial (∼ 111.5-11.7 ka BP). The climate of the last glacial was cold and dry, indicated by low arboreal pollen (AP) levels. The driest and coldest period corresponds to Marine Isotope Stage (MIS) 2 (∼ 28-14.5 ka BP), which was dominated by highest values of xerophytic steppe vegetation.Our high-resolution multi-proxy record shows rapid expansions and contractions of tree populations that reflect variability in temperature and moisture availability. These rapid vegetation and environmental changes can be related to the stadial-interstadial pattern of Dansgaard-Oeschger (DO) events as recorded in the Greenland ice cores. Periods of reduced moisture availability were characterized by enhanced occurrence of xerophytic species and high terrigenous input from the Lake Van catchment area. Furthermore, the comparison with the marine realm reveals that the complex atmosphere-ocean interaction can be explained by the strength and position of the westerlies, which are responsible for the supply of humidity in eastern Anatolia. Influenced by the diverse topography of the Lake Van catchment, more pronounced DO interstadials (e.g., DO 19, 14, 12 and 8) show the strongest expansion of temperate species within the last glacial. However, Heinrich events (HE), characterized by highest concentrations of ice-rafted debris (IRD) in marine sediments, cannot be separated from other DO stadials based on the vegetation composition in eastern Anatolia. In addition, this work is a first attempt to establish a continuous microscopic charcoal record for the last glacial in the Near East.It documents an immediate response to millennial-scale climate and environmental variability and enables us to shed light on the history of fire activity during the last glacial.

Biomarkers in Lake Van sediments reveal dry conditions in eastern Anatolia during 110.000–10.000 years B.P.

“…Further support for dry conditions comes from pollen studies. Here an oak steppe‐forest during the climate optimum at 129 to 124 ka and a more coniferous dominated forest at 124 to 111.5 ka was replaced by steppic herbaceous plants leading to arid desert‐steppe vegetation in Eastern Anatolia from 75 ka to 12 ka [ Litt et al ., ; Pickarski et al ., , ].…”

“…Further support for dry conditions comes from pollen studies. Here an oak steppe-forest during the climate optimum at 129 to 124 ka and a more coniferous dominated forest at 124 to 111.5 ka was replaced by steppic herbaceous plants leading to arid desert-steppe vegetation in Eastern Anatolia from 75 ka to 12 ka Pickarski et al, 2015aPickarski et al, , 2015b. Geochemistry, Geophysics, Geosystems 10.1002/2016GC006621 [Stockhecke et al, 2016], the isotopic values of dD C29 and dD C37 , and the ACE index.…”

A new high-resolution pollen sequence at Lake Van, Turkey: insights into penultimate interglacial–glacial climate change on vegetation history

“…In contrast, the identical AP composition oscillates between ∼ 1 and 10 % during the orbitally equivalent MIS 3 (ca. 61-28 ka; Pickarski et al, 2015b). The different amplitude in arboreal pollen percentages in both glacial stages and a generally dense temperate grass steppe during MIS 6e suggest more available moisture (Fig.…”

“…At Lake Van, cold periods are generally characterized by (i) extensive steppe vegetation when tree growth was inhibited either by dry and cold or low atmospheric CO 2 conditions Pickarski et al, 2015b), (ii) high dinoflagellate concentration (Spiniferites bentorii, which tolerates high water salinity conditions and suggests low aquatic bioproductivity; Fig. 2a), and (iii) high regional mineral input derived from the basin slopes (low Ca / K ratio; Kwiecien et al, 2014;Fig.…”

“…At Lake Van, MIS 6e reveals clear evidence of climate variability due to rapid alternation in abiotic and biotic proxies, such as oxygen isotopes, Ca / K ratio, and pollen data similar to the largest DO 17 to 12 during MIS 3 (ca. 60-44 ka; Pickarski et al, 2015b tervals, MIS 6e and MIS 3, started at the point of summer insolation maxima. Here, the Northern Hemisphere insolation values reached the interglacial level at the beginning of MIS 6e comparable with MIS 7e (Fig.…”