气候变化领域集成服务门户

Geomorphic evidence suggests that shorelines of 100-200 m above the modern lake levels were common across the Tibetan Plateau during late Marine Isotope Stage (MIS) 3. The timing of this lake-level highstand is mainly based on radiocarbon ages. Problems surrounding the ages of lacustrine sediments at or beyond the limit of the radiocarbon-dating method have created a need for alternative geochronometers. Chronological advances during the last decade have renewed interest in the timing of events beyond the limit of radiocarbon dating. Here, we synthesize published data for elevated lacustrine landforms of 48 lakes on the Tibetan Plateau, in order to provide a thorough perspective on the timing and pattern of lake-level changes in this alpine area during the late Quaternary. The ages of these elevated shore features reveal a long-term trend of relative lake-level fall from at least MIS 5, instead of a peak in MIS 3, as previously thought. Dating lacustrine terrace sequences reveals that the rate of lake-level fall ranged from similar to 1 to 3 mm a(-1), comparable with that of related river downcutting across the plateau. Palaeoclimatic proxy records point to a sustained drying since the Last Interglacial, suggesting that long-term aridification might be the culprit for this widespread and progressive lake-level fall.