Climate variability over the last 92 ka in SW Balkans from analysis of sediments from Lake Prespa

Abstract

Abstract. The transboundary Lake Prespa (Albania/former Yugoslav Republic of Macedonia/Greece) has been recognized as a conservation priority wetland. The high biodiversity encountered in the catchment at present points to the refugial character of this mountainous region in the southwestern Balkans. A lake sediment core retrieved from a coring location in the northern part of the lake was investigated through sedimentological, geochemical, and palynological analyses. Based on tephrochronology, radiocarbon and electron spin resonance (ESR) dating, and cross correlation with other Northern Hemisphere records, the age model suggests that the basal part of core Co1215 reaches back to 92 ka cal BP. Here we present the responses of this midaltitude site (849 m a.s.l.) to climate oscillations during this interval and assess its sensitivity to millennial-scale variability. Endogenic calcite precipitation occurred in marine isotope stages (MIS) 5 and 1 and is synchronous with periods of increased primary production (terrestrial and/or lacustrine). Periods of pronounced phytoplankton blooms (inferred from green algae and dinoflagellate concentrations) are recorded in MIS 5 and MIS 1 and suggest that the trophic state and lake levels underwent substantial fluctuations. Three major phases of vegetation development are distinguished: the forested phases of MIS 5 and MIS 1 dominated by deciduous trees with higher temperatures and moisture availability, the open landscapes of MIS 3 with significant presence of temperate trees, and the pine-dominated open landscapes of MIS 4 and MIS 2 with lower temperatures and moisture availability. Our findings suggest significant changes in forest cover and landscape openness, as well as in the properties of the vegetation belts (composition and distribution) over the period examined. The study area most likely formed the upper limit of several drought-sensitive trees (temperate tree refugium) at these latitudes in the Mediterranean mountains.

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

“…These regions are highly sensitive to short-term vegetation changes as recognized by steppe-dominated open landscapes during stadials and increased range of temperate tree taxa during interstadials (e.g., Allen et al, 2000Allen et al, , 1999Follieri et al, 1998;Langgut et al, 2011;Lézine et al, 2010;Müller et al, 2011;Panagiotopoulos et al, 2014;Shumilovskikh et al, 2014). In contrast to southern Europe, high-resolution and continuous terrestrial sedimentary records displaying abrupt climate oscillations are rare in the entire Near East.…”

“…5.2. (a) δ 18 O-profile from NGRIP ice core, Greenland (NGRIP members, 2004), labeled with DO 1 to 19 and HE 1 to HE 6 ; (b) Lake Van arboreal pollen record (AP in %, black line) with 10-fold exaggeration (gray line); (c) marine arboreal pollen record (Core 9509) obtained from the south-eastern Levantine Basin (south-eastern Mediterranean Sea; Langgut et al, 2011); (d) AP record from the SE Black Sea (core 22-GC3 for the period from 10 to 18 ka BP after Shumilovskikh et al (2012) and core 25-GC1 for the sequence between 19 and 63 ka BP (Shumilovskikh et al, 2014); (e) arboreal pollen record from Tenaghi Philippon, Greece (Müller et al, 2011); (f) AP record from Lago Grande di Monticchio, southern Italy (Allen et al, 1999). MIS -Marine Isotope Stage.…”

“…As described above, this millennial-scale variability in the proxy record was indirectly modulated by orbitaldriven changes and variations in the atmospheric circulation of the Northern Hemisphere (e.g., Cacho et al, 2000Cacho et al, , 1999Chapman and Shackleton, 1999;Hemming, 2004;Hodell et al, 2008;McManus et al, 1999;Rasmussen et al, 2014;Wolff et al, 2010). Consequently, the vegetation and environmental conditions at Lake Van respond to abrupt shifts in temperature and moisture availability related to the position and strength of the westerlies, which brought mild and humid conditions from the North Atlantic into the eastern Mediterranean region (Akçar and Schlüchter, 2005;Allen et al, 1999;Fletcher et al, 2010;Müller et al, 2011;Roberts et al, 2008). The Lake Van δ 18 O bulk signature supports the suggestion of favorable environment by the receipt of isotopically depleted meltwater supply and/or increased precipitation between ∼ 57 and 54 ka BP (δ 18 O bulk from −1.21 up to ∼ 1 ‰; Fig.…”

“…The reduction of oceanic heat transport (weakening or shut down of the AMOC; Böhm et al, 2014;Bond and Lotti, 1995;Bond et al, 1993;Broecker, 1994;Cacho et al, 2000Cacho et al, , 1999Chapman and Shackleton, 1999) led to significantly cooler Mediterranean SST's and climatic conditions in the Mediterranean region (e.g., Allen et al, 1999;Fletcher et al, 2010;Müller et al, 2011;Sánchez Goñi et al, 2002;Tzedakis, 2005;Tzedakis et al, 2004). According to Kwiecien et al (2009), a decreasing atmosphere-sea-surface thermal gradient of the Mediterranean Sea would have caused a reduction in the frequency and strength of storm tracks, which were responsible for an intensifying aridity in the eastern Mediterranean region.…”

“…Long-term terrestrial pollen records from the central and eastern Mediterranean, for example several crater lakes in Italy (e.g., Lagaccione, Lago di Vico, Lazio Valle di Castiglione, Stracciacappa; Follieri et al, 1998), Lago Grande di Monticchio (Italy; e.g., Allen et al, 1999), Lake Prespa (between Albania, Republic of Macedonia, and Greece; Panagiotopoulos et al, 2014), Lake Ohrid (Albania; Lézine et al, 2010) and Tenaghi Philippon (Greece; e.g., Müller et al, 2011) demonstrate a clear vegetation response to millennialscale climate variability during the last glacial. These regions are highly sensitive to short-term vegetation changes as recognized by steppe-dominated open landscapes during stadials and increased range of temperate tree taxa during interstadials (e.g., Allen et al, 2000Allen et al, , 1999Follieri et al, 1998;Langgut et al, 2011;Lézine et al, 2010;Müller et al, 2011;Panagiotopoulos et al, 2014;Shumilovskikh et al, 2014).…”