Hydroclimate footprint of pan-Asian monsoon water isotope during the last deglaciation.

He, C; Liu, Z; Otto-Bliesner, B L; Brady, E C; Zhu, C; Tomas, R; Clark, P U; Zhu, J et al. · Sci Adv · 2021

basic_science · Level V

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Abstract

Oxygen isotope speleothem records exhibit coherent variability over the pan-Asian summer monsoon (AM) region. The hydroclimatic representation of these oxygen isotope records for the AM, however, has remained poorly understood. Here, combining an isotope-enabled Earth system model in transient experiments with proxy records, we show that the widespread AM δ<sup>18</sup>O<sub>c</sub> signal during the last deglaciation (20 to 11 thousand years ago) is accompanied by a continental-scale, coherent hydroclimate footprint, with spatially opposite signs in rainfall. This footprint is generated as a dynamically coherent response of the AM system primarily to meltwater forcing and secondarily to insolation forcing and is further reinforced by atmospheric teleconnection. Hence, widespread δ<sup>18</sup>O<sub>p</sub> depletion in the AM region is accompanied by a northward migration of the westerly jet and enhanced southwesterly monsoon wind, as well as increased rainfall from South Asia (India) to northern China but decreased rainfall in southeast China.