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n‐Alkanes are widely used in paleoenvironmental reconstructions. However, our understanding of changes in the distribution of n‐alkanes with climatic and environmental factors remains unclear in arid/semi‐arid regions. We sampled 26 surface sediments from three climatic zones across the southwestern Tibetan Plateau to evaluate the sensitivity of chain length distributions of n‐alkanes to climatic and environmental parameters. Our observations demonstrate that average chain length (ACL), proportion of aquatic macrophyte (Paq), carbon preference index (CPI) and ratio of the contents of nC27 and nC31 (nC27/nC31) are all sensitive to hydroclimatic conditions. In contrast to commonly‐adopted assumptions, the correlations between these indices and hydrological parameters are not always good, which indicates that the interpretation of n‐alkane indices is special on the southwestern Tibetan Plateau. These might be related to the vegetation characteristics and seasonality of biological activity, and need to be considered in paleoclimatic reconstruction. The impact of seasonal precipitation on n‐alkanes indices was also evaluated. [ABSTRACT FROM AUTHOR]

Knowledge of the origin of past climatic variations on annual to decadal timescales is important for assessing the likelihood of the occurrence of similar variations in the future. Here we present a high-resolution (82-μm) element record, obtained using Synchrotron Radiation X-ray Fluorescence, from the sediments of Toson Lake in the northeastern Tibetan Plateau. The record, which spans the last ∼1100 yr, exhibits variability on an annual to decadal scale. The results of principal component analysis of the element dataset indicates that the first three principal components reflect variations in detrital inputs (via runoff and possibly eolian activity), drought conditions and temperature variations, respectively. Spectral analysis of samples scores on these components reveals strong El Niño-Southern Oscillation (ENSO)-like variability at periods of 3–8 years which indicates that the regional climatic variability was effected by ENSO events over the last ∼1100 yr. On the centennial time scale, the element data and TOC record suggest a warm and dry climate during the Medieval Warm Period (MWP) and a cold and wet Little Ice Age (LIA). The early 20th century was a warm interval, and drier than the LIA but wetter than the MWP. [ABSTRACT FROM AUTHOR]