Climate change on the Tibetan Plateau in response to shifting atmospheric circulation since the LGM

Abstract

The Tibetan Plateau (TP) is primarily influenced by the northern hemispheric middle latitude Westerlies and the Indian summer monsoon (ISM). The extent, long-distance effects and potential long-term changes of these two atmospheric circulations are not yet fully understood. Here, we analyse modern airborne pollen in a transition zone of seasonally alternating dominance of the Westerlies and the ISM to develop a pollen discrimination index (PDI) that allows us to distinguish between the intensities of the two circulation systems. This index is applied to interpret a continuous lacustrine sedimentary record from Lake Nam Co covering the past 24 cal kyr BP to investigate long-term variations in the atmospheric circulation systems. Climatic variations on the central TP widely correspond to those of the North Atlantic (NA) realm, but are controlled through different mechanisms resulting from the changing climatic conditions since the Last Glacial Maximum (LGM). During the LGM, until 16.5 cal kyr BP, the TP was dominated by the Westerlies. After 16.5 cal kyr BP, the climatic conditions were mainly controlled by the ISM. From 11.6 to 9 cal kyr BP, the TP was exposed to enhanced solar radiation at the low latitudes, resulting in greater water availability.

Identifying separate impacts of climate and land use/cover change on hydrological processes in upper stream of Heihe River, Northwest China

“…A large change in precipitation occurring during this period was especially noticeable. It is noteworthy that the trends plotted in Figure seemed to be influenced by a decadal climatic cycle in which there was a decline in precipitation and runoff found approximately at every decadal boundary, due to the study area that was primarily influenced by the northern hemispheric middle latitude westerlies and the Asia summer monsoon (Zhu et al, ). The annual variation of precipitation and runoff was not significant at p < 0.1 (Figure ) over the entire period of study.…”

Separation of the Climatic and Land Cover Impacts on the Flow Regime Changes in Two Watersheds of Northeastern Tibetan Plateau

“…This indicates that variation of water vapor sources due to climate change is more obvious in MXC than in YLC. This is mainly because the Asia summer monsoon tends to affect the MXC region more significantly than the YLC region resulting in more water vapor received in MXC than YLC region [22]. However, the results of precipitation and streamflow trend magnitudes did not pass the significance test of 0.05, except for the streamflow in the MXC region during the period 1980-1995.…”

“…The Yingluoxia catchment (YLC) and Minxian catchment (MXC), utilized in this study, are situated in the northeastern Tibetan Plateau, which are primarily influenced by the northern hemispheric middle latitude Westerlies and the Asia summer monsoon, respectively [22,23]. The two watersheds are nearly located at the same longitude, but quietly different latitude.…”

Climate Change and Drought Events in the Geochemical Records of the Lacustrine Deposits in the Southeastern Tibetan Plateau

“…Studying the chemical proxies of elements in lacustrine sediments allows us to understand the close interdependence of the Asian monsoon evolution and the global climate changes [4–11]. The Tibetan Plateau (TP) has always been the object of intense climate research [12, 13]. Previous research suggests that the TP is one of the regulators of global climate [14, 15].…”