Climatic changes documented by stable isotopes of sedimentary carbonate in Lake Sugan, northeastern Tibetan Plateau of China, since 2 kaBP

Lake Sugan at the northern edge of the Qaidam Basin was selected as the research object. The temporal sequence of sedimentary cores retrieved from Lake Sugan since 2 kaBP was reconstructed using the ²¹⁰Pb, AMS ¹⁴C and conventional ¹⁴C dating methods. Carbon and oxygen isotopes of carbonate in the fine-grained lake sediments were analysed. Combined with the changes of δ¹⁸O values of surface water and air temperature observation data in the study area, it might be thought that the δ¹⁸O value of the carbonate indicates effective moisture, and the changes in δ¹³C values are related to annual freeze-up duration of the lake and indirectly indicate air temperature changes in winter half year. From the above, the sequence of climatic changes in the region since 2 kaBP was established. The climatic changes experienced five stages: Warm-dry climate during 0–190 AD; cold-dry climate during 190–580 AD; warm-dry climate during 580–1200 AD (MWP); cold-wet climate during 1200–1880 AD (LIA); cold-dry climate during 1880–1950 AD; and climate warming since 1950s. The air temperature changes in winter half year reflected by carbon isotope since 2 kaBP are in good agreement with the historical literature records and other geologic records, which shows that the climate changes recorded by the stable isotopes from Lake Sugan since 2 kaBP are of universal significance.