Evidence for an abrupt climatic reversal during the Last Interglacial on the northeast Qinghai-Tibetan Plateau

Climatic change over Qinghai-Tibetan Plateau is controlled by alternation of the plateau summer and winter monsoon circulation, which is triggered by thermodynamic and kinetic effects of the high plateau morphology. Loess-paleosol sequences in northeast Qinghai-Tibetan Plateau are investigated to reconstruct variations of the plateau monsoon changes during the Last Glacial-Interglacial cycle. On the basis of grain-size data from two loess-paleosol sequences that can be used as a proxy indicator of the plateau monsoon climate changes, we find a short climatic reversal during transition from the most warm-humid period of the Last Interglacial period (corresponding with marine oxygen isotope stage 5e (MIS 5e)) to the subsequent relatively cold-dry period (corresponding with MIS 5d). In contrast to the Younger Dryas event, this climatic event shifted toward more humid conditions reflects an episode of reduced strength of the plateau winter monsoon and increased influence of the plateau summer monsoon. The age of this paleoclimatic event is estimated at 111-113 ka BP. This climatic reversal expresses instability of the plateau monsoon system during transformation from a wet-warm to a dry-cold climate. It may have been caused by the high topography that amplified climatic change in the Northern Hemisphere during the transition from MIS 5e to MIS 5d. (c) 2006 Elsevier Ltd and INQUA. All rights reserved. Climatic change over Qinghai-Tibetan Plateau is controlled by alternation of the plateau summer and winter monsoon circulation, which is triggered by thermodynamic and kinetic effects of the high plateau morphology. Loess-paleosol sequences in northeast Qinghai-Tibetan Plateau are investigated to reconstruct variations of the plateau monsoon changes during the Last Glacial-Interglacial cycle. On the basis of grain-size data from two loess-paleosol sequences that can be used as a proxy indicator of the plateau monsoon climate changes, we find a short climatic reversal during transition from the most warm-humid period of the Last Interglacial period (corresponding with marine oxygen isotope stage 5e (MIS 5e)) to the subsequent relatively cold-dry period (corresponding with MIS 5d). In contrast to the Younger Dryas event, this climatic event shifted toward more humid conditions reflects an episode of reduced strength of the plateau winter monsoon and increased influence of the plateau summer monsoon. The age of this paleoclimatic event is estimated at 111-113 ka BP. This climatic reversal expresses instability of the plateau monsoon system during transformation from a wet-warm to a dry-cold climate. It may have been caused by the high topography that amplified climatic change in the Northern Hemisphere during the transition from MIS 5e to MIS 5d. (c) 2006 Elsevier Ltd and INQUA. All rights reserved.