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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.
