Multi-decadal periods of enhanced aeolian activity on the north-eastern Tibet Plateau during the last 2ka

The north-eastern Tibetan Plateau is regarded as key area for the understanding of the Holocene paleoclimate in central Asia. During the last decade a special emphasis has been placed on multi-decadal to millennial scale climate fluctuations, especially in the context of the recent climate change. However, most reconstructions are based on lake sediments, tree rings and speleothems whereas only little information from terrestrial archives is included. This study presents multi-decadal scale climate fluctuations based on optical stimulated luminescence (OSL) ages from aeolian sediments from three catchment areas. Six phases of enhanced aeolian accumulation during the last 2000 years, each lasting around 80-200 years were identified. The first three phases (1630-1725 CE, 1450-1530 CE and 1250-1350 CE) occurred during the Little Ice Age; the other three (750-950 CE, 390-540 CE, 50-225 CE) during the so-called dark ages cooling. Aeolian processes were strongly reduced during the medieval climate anomaly. A comparison with other proxy records indicates that the formation of aeolian archives on the north-eastern Tibetan Plateau during the late Holocene is facilitated by cool and dry climate conditions during times of weaker Asian Summer Monsoon and probably enhanced westerlies. The results show that short term climate fluctuations can be reconstructed from non-continuous and heterogeneous terrestrial archives in a semi-arid environment, provided a sufficient number of OSL ages from aeolian sediments is available.