Rapid northward shift of the Indian Monsoon on the Tibetan Plateau at the end of the Little Ice Age

Abstract

Variations in the Indian Monsoon (IM) and Westerlies (WS) significantly affect the climate on the Tibetan Plateau (TP) and have widespread ecological and socioeconomic impacts on the whole of Asian society. So far, however, the rate and magnitude of changes in the IM have still remained unclear. Here we report for the first time that the IM rapidly shifted northward at the end of the Little Ice Age (LIA). We used sediment proxies for humidity and moisture sources from the Taro Co Lake, which is located in the transition zone between the WS and IM. Our comprehensive survey of climate records for the TP and its peripheral mountain ranges revealed that the northern boundary of the IM (i.e., the southern boundary of the WS) lay along the southern slope of the Gandise Range (~29.5°N) in the late LIA. In contrast, it passed quickly over the Gandise Range by at least 1.5° in latitude at the end of the LIA. Our results suggest that this rapid climatic shift was potentially triggered by the counteracting effects of blocking by the TP and its marginal orography, which hindered the northward movement of the IM, and the pulling thermal gradient of the TP.

Millennial‐ to centennial‐scale anti‐phase relationship between the Westerlies and the East Asian summer monsoon and its cultural response along the Silk Roads after a great earthquake in southern Altay ~ 3500 cal a BP

“…Zhang et al . 2017). These data imply that it is very difficult to obtain completely consistent paleoclimatic records from different lakes in different geomorphic and hydroclimatic backgrounds.…”

“…This phenomenon was considered to be the result of northward shift of the ISM in response to the rapid heating of the Tibetan Plateau (e.g. Zhang et al 2017). These data imply that it is very difficult to obtain completely consistent paleoclimatic records from different lakes in different geomorphic and hydroclimatic backgrounds.…”

Responses of sedimentary proxy indicators to lake-level fluctuations on the central Tibetan Plateau since the last deglaciation

“…Wang et al (2020a) that Paq variations in the lakes of the TP are mainly controlled by the ratio of submerged and terrestrial plants. Paq generally reflects changes in within-lake productivity and it has been proposed as a potential water depth indicator (Callegaro et al, 2018;Chu et al, 2014;Liu et al, 2017;Pu et al, 2011;Sun et al, 2018;Wang et al, 2016Wang et al, , 2017aWang et al, , 2020bZhang et al, 2017).…”

“…ACL 28-32 is the average chain length of waxy lipid compounds from higher terrestrial plants, and the carbon chains of lipid compounds produced by grasses and herbs are longer than those of trees (Hughen et al, 2004;Poynter et al, 1989;Pu et al, 2013;Zhang et al, 2017). Hence, higher ACL 28-32 values are linked to abundant grasses and herbaceous plants in the watershed, indicating a relatively dry environment, and vice versa (Carr et al, 2014;Eley and Hren, 2018;Gao et al, 2014;Sachse et al, 2006;Schefuss et al, 2003;Schouten et al, 2007;Tipple and Pagani, 2013).…”