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We present a high-resolution oxygen isotope record from authigenic carbonate (δ 18 O carb ) from Lake Xiarinur (Inner Mongolia) since the last deglaciation. The lake is located at the modern northern limit of the monsoon, and is therefore sensitive to the extension of the East Asian summer monsoon. Based on calibration against the instrumental record, the δ 18 O car variation has been interpreted as changes in atmospheric circulation pattern on decadal time scales. On longer time scales, the δ 18 O carb in lake sediments could be mainly regulated by the relative contribution of nearby (remote) water-vapor sources associated with subtropical (tropical) monsoon through changes in the distance from sources to the site of precipitation. Increased remote water vapors from tropical monsoon would lead to lighter isotope value in our study site. Through time the δ 18 O carb record in Lake Xiarinur indicate a notable weak tropical monsoon during the Younger Dryas, a gradual increasing monsoon from the early Holocene and weakening monsoon after the middle Holocene. Oxygen isotope records from lakes and stalagmite in the Asian monsoon region across different localities show a general similar temporal pattern since the last deglaciation, and highlight a fundamental role of the tropical monsoon. [ABSTRACT FROM AUTHOR]

A progressive warming or a long-term cooling trend during the Holocene remain controversial both at a regional and global scale. One possible reason for this discrepancy could be seasonality and uncertainties in the biases of various temperature proxies. Here, we present the distributions of archaeal isoprenoid glycerol dialkyl glycerol tetraethers (iGDGTs) from two soil transects in Arid Central Asia (ACA): a temperature (elevation) transect at Mount (Mt.) Tienshan (n = 18) in Northwest China and a precipitation transect in northern Iran (n = 48), to assess the impacts of temperature and precipitation on the distributions of soil iGDGTs, respectively. In addition, changes in archaeal community structure are detected by high-throughput sequencing in 9 soils from different elevations at Mt. Tienshan. Thereafter, a well-constrained, soil iGDGT-based Holocene temperature reconstruction is obtained for the first time from a loess-paleosol sequence (LJW10) at Mt. Tienshan. Our results indicate that mean annual air temperature (MAAT) dominates the distribution of soil iGDGTs, and the TEX 86 (TetraEther indeX of tetraethers consisting of 86 carbon atoms) proxy exhibits significant positive correlations with MAAT in ACA. There is no direct evidence that seasonal changes in temperature and non-thermal factors (e.g., MAP) significantly influence soil TEX 86 in ACA, which is further supported by a dominance of Thaumarchaeotal Group I.1b in Mt. Tienshan soils. Based on the local soil TEX 86 -MAAT calibration from Mt. Tienshan, the estimated MAAT value of the topmost sample from the LJW10 section agrees well with the instrumental MAAT. Our MAAT record supports the long-term warming trend observed in numerous Northern Hemisphere (NH) annual/winter temperature records, model simulations and paleoclimate data assimilation, which may be primarily attributed to the changes in annual mean insolation, greenhouse gases and NH ice sheets dynamics. • The TEX 86 proxy shows a positive correlation with MAAT for soils in ACA. • Thaumarchaeotal Group I.1b is dominant for soils from Mt. Tienshan. • Our first soil TEX 86 -based MAAT record supports Holocene warming in ACA. [ABSTRACT FROM AUTHOR]

The abundance and distribution of long-chain n-alkanes in sedimentary archives have been proposed as plant-derived paleoenvironmental proxies. The reliable application of these proxies hinges on comprehensive understandings drawn from investigations of living plants. However, previous studies have predominantly relied on narrow environmental gradients and limited datasets sourced from local and regional sampling. As a result, our comprehension of how n-alkanes in living plants respond to climate factors on larger spatial scales remains unclear, especially across different plant functional types (PFTs). In this study, we analyzed the abundance and distribution of n-alkanes in the leaves of 552 plant samples from diverse regions in China and explored the variability of leaf wax n-alkanes across gradients of climate and PFTs. Average chain length (ACL) and carbon preference index (CPI) exhibit statistically significant differences between various PFTs, and the ratio of C 33 /(C 31 + C 33) holds the potential to distinguish between C 3 and C 4 vegetation types. The n-alkane concentration (Σalk) is primarily controlled by precipitation, with a notable negative correlation between Σalk and mean annual precipitation (MAP) that is independent of PFTs. Overall, ACL is negatively related to MAP and positively to mean annual temperature (MAT), but the relationship varies across PFTs. MAT is a stronger driver of ACL for C 4 herbs and woody plants, while MAP exerts a more pronounced influence on C 3 herbs. CPI in most PFTs shows no correlation with environmental variables. These findings indicate Σalk is a good indicator of precipitation, and ACL is indicative of precipitation or temperature depending on the specific PFT; CPI appears unsuitable as a climate indicator and great caution should be exercised in using CPI records in paleoclimate research. • A study of leaf wax n-alkanes covering the entire mainland China was performed. • Differences in n-alkane distribution among PFTs do not distinguish taxonomically. • Σalk is a good indicator of precipitation. • CPI is poorly sensitive to environmental factors. • ACL is an indicator of precipitation or temperature depending on the specific PFT. [ABSTRACT FROM AUTHOR]