Late Holocene Temperature And Precipitation Variations Documented By An Alpine Lake In The Northeastern Tibetan Plateau

The Tibetan Plateau is known for the‘third pole of the Earth’and the‘Asian water tower’,and its climate and environment have undergone significant changes in the context of global warming,further affecting ecological security and endangering regional social development.It is of great significance that clarifying the climate change on the Tibetan Plateau during the late Holocene and its response to global climate change,for the prediction of future climate change in this region.Based on a reliable dating framework established by AMS¹⁴C dates,late Holocene records of multiple physical and chemical indicators and branched glycerol dialkyl glycerol tetraethers from sediments of alpine Lake Bihu from Dalijia Mountains in the northeastern Tibetan Plateau（NETP）were provided.The study 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～3500 years.The results and conclusions of the study are listed as follows:（1）The MAF reconstruction shows obvious fluctuations on decadal to centennial timescales with an overall cooling trend before Common Era（CE）and a general warming trend after CE,and rapid warming after 1900 CE.The absolute values of the reconstructed temperature range from 0.70 to 3.98°C,with an average of 2.20°C.（2）The precipitation reconstructed from multiple physical and chemical indicators reflects the high-frequency variability of the East Asian summer monsoon（EASM）.The maximum precipitation and temperature on the NETP occurred during the Medieval Warm Period（MWP,～800–1,400 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 after compared our record with other climate records;moreover,the decadal to centennial temperature fluctuations were consistent on a large spatial scale.（3）Our results indicate that temperature variability during the late Holocene was primarily controlled by solar radiation,interrupted by multiple decades of global 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 Ni（?）o–Southern Oscillation,Intertropical Convergence Zone,and Western Pacific Subtropical High）.Overall,our results provide robust evidence for rapid global climate response between different regions,especially in high mountains,in the past,present,and potentially in the future.