Late Holocene temperature and precipitation variations in an alpine region of the northeastern Tibetan Plateau and their response to global climate change

Knowledge of temperature and precipitation variations on the northeastern Tibetan Plateau (NETP) during the recent past can improve our understanding of late Holocene regional climate change and its response to global climate change, in the past and potentially the future. Based on records of multiple geochemical indicators and branched glycerol dialkyl glycerol tetraethers from the sediments of alpine Lake Bihu on the NETP, we reconstructed high-resolution precipitation sequences and quantified the variation of the mean air temperature of months above freezing (MAF, between May and October) over the past similar to 3500 years. The MAF reconstruction shows obvious fluctuations on decadal to centennial timescales, and the absolute values of the reconstructed temperature range from 0.70 to 3.98 degrees C, with an average of 2.19 degrees C. The precipitation record reflects the highfrequency variability of the East Asian summer monsoon (EASM). The maximum precipitation and temperature on the NETP occurred during the Medieval Warm Period (MWP, similar to 800-1400 CE), rather than during the Current Warm Period (CWP, the last 150 years). We also observed broadly similar patterns of warm-wet and cold-dry climatic variations over the NETP and the broader EASM region; moreover, the decadal to centennial temperature fluctuations were consistent on a large spatial scale. Our results indicate that temperature variability during the late Holocene was primarily controlled by solar radiation, interrupted by multiple decades of successive volcanic eruptions. In addition, anomalous and rapid warming during the CWP may also be related to the unprecedented increase in atmospheric greenhouse gases. Precipitation variability in this region, driven by changes in the EASM, may have been primarily a response to changes in total solar irradiance and associated changes in atmospheric-oceanic modes (e.g., the El Nin similar to o-Southern Oscillation, Intertropical Convergence Zone, and Western Pacific Subtropical High). Overall, our results provide robust evidence for global climate teleconnections between different regions, especially in high mountains, in the past, present, and potentially in the future.