Sedimentary Black Carbon Isotope Record of Holocene Climate Changes on the Northeastern Tibetan Plateau

The northeastern Tibetan Plateau (TP) is an unique area for studying the interactions between the Asian Monsoonal climate and the westerlies. However, significant contraries on Holocene paleoclimate evolution are still exist. To better understand the climate history on the northeastern TP particularly its variability, we here investigated the stable carbon isotope compositions of Black Carbon (BC) (delta C-13(BC)) in Lake Gyaring sediment core from the source area of the Yellow River. The delta C-13(BC) values were relatively positive before similar to 6.2 cal kyr BP indicating that the climate on northeastern TP was warm and dry during the first half of the Holocene, while the decreasing trend thereafter reflects that the climate on the northeastern TP has become generally cooler and wetter since the middle Holocene. Superimposed on the long-term paleoclimate evolution pattern, at least seven centennial-scale cold-wet events characterized by significant delta C-13(BC) depletions occurred at about 8.4, 7.5, 6.2, 5.0, 4.3, 2.7, and 0.9 cal kyr BP. Those abrupt climate events well corresponded to the weak Asian Monsoon episodes and the ice-rafted debris records in the North Atlantic. We speculate that the cold climate signals from the North Atlantic resulted from the sea-ice expansion have been transported to the northeastern TP through the westerlies leading to a cold conditions there. Besides, the anomalous easterly water vapor transportation over the northern periphery of the TP during weak monsoon intervals has generated the wet conditions on the northeastern TP.