Late Holocene Mongolian climate and environment reconstructions from brGDGTs, NPPs and pollen transfer functions for Lake Ayrag: Paleoclimate implications for Arid Central Asia

A coupled pollen-brGDGT paleoclimate reconstruction approach has been tested to provide independent and robust estimates of Holocene climate environment changes in the extremely arid mountainous areas ranging from northern Arid Central Asia (ACA) Mongolian Plateau. The two proxies were calibrated for both global local modern data sets (NMSDB). This multi-proxy was then applied a sediment core collected Lake Ayrag, Arkhangai, covering Late Holocene. In addition brGDGTs pollen, we also performed magnetic susceptibility, micro-XRF, elemental isotopic bulk chemistry, Non-Pollen Palynomorph (NPP) analyses on Ayrag sediments order better understand lake system human impact dynamics. While globally record (both pollen brGDGTs) displayed slight millennial-scale cooling, locally results exhibit centennial-scale oscillations such as 4.2 3.5 kyr events, Roman Warm Period (RWP), Dark Ages Cold (DACP), Medieval (MWP) Little Ice Age (LIA). These vegetation are discussed with regard main historical occupation events documented by pastoralism proxies, especially Xiongnu, Mongol Empire, Mandchou Soviet periods. systems currently dominating Plateau difficult resolve because inter-annual variability is pronounced. However, precipitation mainly occurs summer (easterly monsoon driven) when winter Westerlies lead air mass movement. past, biomarkers exhibited anti-correlated trends annual temperature: over last 4000 kcal yr BP, warm periods (MWP, RWP) dry cold (LIA, DACP, kyrs) humid. Thus, East Asian Summer Monsoon (i.e., wet conditions dominant during summer) seems not have influenced central Holocene, which could remained dominated Westerlies/Siberian High cells conflict. comparison between other records Baikal area (Dulikha), (D3L6, D1L1, NRX, ATM), continental China (Kesang, Baluk Tonnel caves, XRD section) Loess (Huangye Xianglong caves) suggests that front oscillated since Early synthesis following strictly same (locally vs. pollen-inferred climate) all ACA available helps us paced centennial their consequences societies.