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Abstract
Abstract. Marine isotope stages (MIS) 11 has been proposed as an analog for the present interglacial; however, terrestrial records of this time period are rare. Sediments from Lake El'gygytgyn (67°30' N, 172°5' E) in Far East Russia contain a 3.56 Ma record of climate variability from the Arctic. Here, we present the first terrestrial Arctic reconstruction of environmental and climatic changes from MIS 8 through 12 (289 to 464 ka) using organic geochemical proxies. Terrestrial vegetation changes, as revealed by plant leaf wax (n-alkane) indices and concentrations of arborinol (a biomarker for trees), show increased tree cover around the lake during interglacial periods, with higher concentrations observed during MIS 11 as compared to MIS 9. A similar pattern is also observed in records of aquatic productivity revealed by molecular indicators from dinoflagellates (dinosterol), eustigmatophyte algae (long-chain (C28–C32) 1, 15 n-alkyl diols) in addition to short-chain n-alkanes, where aquatic productivity is highest during MIS 11. Changes recorded in these molecular proxies show a similar structure to relative temperature variability as recorded by the MBT/CBT (Methylation of Branched Tetraether/Cyclization of Branched Tetraether) paleothermometer, based on branched glycerol dialkyl glycerol tetraethers (GDGTs). Additionally, relative MBT/CBT temperature changes generally track pollen and diatom δ18O temperature estimates, compiled by other studies, which suggest glacial-interglacial temperature changes of ~ 9 to 12 °C. These records of environmental and climatic change indicate Arctic sensitivity to external forcings such as orbital variability and atmospheric greenhouse gas concentrations. Overall, this study indicates that organic geochemical analyses of the Lake El'gygytgyn sediment archive can provide critical insight into the response of lake ecosystems and their sensitivity in high latitude regions.
Highlights
Hydrology and Marine isotope stage (MIES)a11rthhasSbeyesn tperomposed as an analog to modern climate conditionsS, wciiteh norcbietasl configurations similar to today and greenhouse gas concentrations at preindustrial levels (Loutre and Berger, 2002; EPICA community members, 2004)
Branched glycerol dialkyl glycerol tetraethers (GDGTs) concentrations range from 0.09 to 0.99 μg g−se1d and on average are more abundant during interglacial periods (Fig. 2e)
Methylation of Branched Tetraethers (MBT)/Cyclization of Branched Tetraethers (CBT) derived temperature estimates range from −9.2 to 3.0 ◦C when applying the global soils calibration of Weijers et al (2007b) and from −3.5 to 6.4 ◦C when applying the MBT /CBT soils calibration of Peterse et al (2012)
Summary
Hydrology and Marine isotope stage (MIES)a11rthhasSbeyesn tperomposed as an analog to modern climate conditionsS, wciiteh norcbietasl configurations similar to today and greenhouse gas concentrations at preindustrial levels (Loutre and Berger, 2002; EPICA community members, 2004). The sediment record obtained from Lake El’gygytgyn in Far East. Arctic Russia containTs ha ceonCtinruyooussaprchhievereof climate variability since the middle Pliocene and permits critical analysis of the structure, and corresponding response of this western Beringian ecosystem to changes during the MIS 11 “super” interglacial period. The catchment area sits in an impact structure formed at 3.58 ± 0.04 Ma (Layer, 2000), with a rim-to-rim diameter of 18 km and a catchment area of approximately 293 km (Nolan and Brigham-Grette, 2007). Lake ice formation occurs by October, and persists to July
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