Holocene climate changes in the monsoon/arid transition reflected by carbon concentration in Daihai Lake of Inner Mongolia

Abstract

Two sediment cores recovered in the central part of Daihai Lake in north-central China were analysed at 2-to 4-cm intervals for total inorganic and organic carbon (TIC and TOC) concentrations. The TIC concentration is inferred to reflect temperatures over the lake region and an increase in the TIC concentration implies an increase in the temperature. TOC concentration is considered to reflect the precipitation in the lake basin and higher TOC concentrations denote more precipitations. Thus AMS 14C time series of the TIC and TOC records of Daihai Lake sediments uncovers a detailed history of changes in temperature and precipitation in north-central China during the last c. 12 000 yr. The Holocene, an epoch of postglacial warmth, started c. 11 500 cal. yr BP, and can be subdivided into three stages: the early (c. 11 500-8100 cal. yr BP), middle (c. 8100-3300 cal. yr BP) and the late Holocene (c. 3300-0 cal. yr BP). The climate was warm and dry during the early Holocene, warm and wet during the middle Holocene, and in the late Holocene became cooler and drier but displayed a relatively warmer and wetter interval between c. 1700 and 1300 cal. yr BP. The Holocene Climatic Optimum, defined as a postglacial episode of both megathermal and megahumid climate, might have occurred in north-central China between c. 8100 and 3300 cal. yr BP, and the climate during this period was variable and punctuated by cool and/or dry events. We infer that changes in the temperature were directly controlled by changes in summer solar radiation in the Northern Hemisphere resulting from progressive changes in the Earth's orbital parameters. Whereas an increase in the monsoonal precipitation could be closely related to an increase in the sea surface temperature of the low-latitude Pacific Ocean, an increase in the temperature and size of the Western Pacific Warm Pool and a westward shifted and strengthened Kuroshio Current in the western Pacific.

Temporally changing drivers for late-Holocene vegetation changes on the northern Tibetan Plateau

“…Furthermore, the variations in TOC content show patterns that are consistent with precipitation reconstructions based on treerings from Delingha in the northern part of the Tibetan Plateau (Shao et al, 2005), indicating that the TOC-related primary productivity in Lake Kusai may be largely controlled by changes in precipitation, as has been widely reported from the arid and semiarid regions in central Asia (e.g. Shen et al, 2005;Xiao et al, 2002Xiao et al, , 2006Mischke et al, 2010). Productivity in the lake increased during periods of higher precipitation resulting in a higher TOC content in the sediments, and conversely decreased during drier periods.…”

Distribution and vegetation reconstruction of the deserts of northern China during the mid‐Holocene

“…In addition, a large amount of geological evidences based on various climate proxies, including magnetic susceptibility [Peterse et al, 2011], pollen assemblages [Jiang et al, 2006;Wang and Feng, 2013], total organic carbon content of lake sediments [Xiao et al, 2006], and lake levels [Yu et al, 2001], from the arid and semiarid regions of northern China suggests that the moisture level during the midHolocene was significantly greater than at the present day. In addition, the results of numerical climate models suggest that the mid-Holocene summer precipitation, and thus the EASM, was stronger in northern China than today [Wang et al, 2010;Zhou and Zhao, 2010;Jiang et al, 2013aJiang et al, , 2013b.…”

Holocene climate evolution of the Ugii Nuur basin, Mongolia

“…This interpretation is based on several aspects. The authigenic production of TIC is subject to various physical lake conditions (temperature, CO 2 , solute concentration) that are partly linked to biomass production (Håkanson and Jansson, 1983;Dean, 1999;Xiao et al, 2006). Optimal conditions for the incorporation of endogenic carbonate minerals in sediments are derived from a combination of these parameters.…”

“…TOC enrichment can be attributed to increased autochthonous bioproduction, dedrital input from the catchment (Dunne et al, 1991;Boyle, 2001;Xiao et al, 2006) and preservation, when covering rates exceed diagenetic decomposition rates (Lerman, 1979;Schütt, 2004a). These diverse mechanisms impede paleoclimatological interpretations inferred from TOC concentrations without additional source signals (e.g., N, δ 13 C) (Meyers, 1994;Xiao et al, 2006;Hartmann and Wünnemann, 2008). Still, various correlative peaks of TIC and TOC suggest a synsedimentary mechanism during some periods.…”