scholarly journals Atlantic meridional overturning circulation modulation of late Pleistocene to middle Holocene Asian summer monsoon variability and palaeoanthropological implications

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Xinxia Li ◽  
Guoqiao Xiao ◽  
Shan Lin ◽  
Xiaoke Qiang ◽  
Hong Ao

Abstract Asia contains more than half the world’s population, and their lives are significantly related to summer monsoon moisture supply. Here, we investigate features and dynamics of late Pleistocene–middle Holocene Asian summer monsoon variability in the Nihewan Basin, North China, which was a critical home for early humans in East Asia throughout the Quaternary. We present new mineral magnetic records between ∼16 and 6 ka from the Yujiagou archeological site in the northern Nihewan Basin, which contains >40 000 stone tools, 2 pottery pieces and 19 686 mammal fossils. Magnetic properties of the Yujiagou section are dominated by pedogenic fine-grained magnetite/maghemite concentration, which ranges from superparamagnetic/single domain up to fine pseudo-single domain sizes. We use multiple environmental magnetic proxies, which measure pedogenic magnetite/maghemite concentration, to document that summer monsoon precipitation was low before ∼14.5 ka and high during the Bölling–Allerød warm period (14.5–12.8 ka), and shifted to low values at the onset of the Young Dryas cold period ∼12.4 ka, followed by a sustained long-term increasing trend from 12.4 to 6 ka. We relate these monsoon precipitation changes to the consistent Atlantic Meridional Overturning Circulation variability, which modulated North Hemisphere temperatures and displacements of Inter-Tropical Convergence Zone and Walker circulation over the Pacific Ocean. The observed large-amplitude deglacial Asian monsoon changes may have played a role in several key evolutionary changes in Asia implicated by the Yujiagou archeological evidence, including Paleolithic to Neolithic culture transition, Asian pottery development, and early human dispersals from Asia to America.

2018 ◽  
Vol 14 (11) ◽  
pp. 1805-1817 ◽  
Author(s):  
Haiwei Zhang ◽  
Hai Cheng ◽  
Yanjun Cai ◽  
Christoph Spötl ◽  
Gayatri Kathayat ◽  
...  

Abstract. Although the collapses of several Neolithic cultures in China are considered to have been associated with abrupt climate change during the 4.2 ka BP event (4.2–3.9 ka BP), the timing and nature of this event and the spatial distribution of precipitation between northern and southern China are still controversial. The hydroclimate of this event in southeastern China is still poorly known, except for a few published records from the lower reaches of the Yangtze River. In this study, a high-resolution record of monsoon precipitation between 5.3 and 3.57 ka BP based on a stalagmite from Shennong Cave, Jiangxi Province, southeast China, is presented. Coherent variations in δ18O and δ13C reveal that the climate in this part of China was dominantly wet between 5.3 and 4.5 ka BP and mostly dry between 4.5 and 3.57 ka BP, interrupted by a wet interval (4.2–3.9 ka BP). A comparison with other records from monsoonal China suggests that summer monsoon precipitation decreased in northern China but increased in southern China during the 4.2 ka BP event. We propose that the weakened East Asian summer monsoon controlled by the reduced Atlantic Meridional Overturning Circulation resulted in this contrasting distribution of monsoon precipitation between northern and southern China. During the 4.2 ka BP event the rain belt remained longer at its southern position, giving rise to a pronounced humidity gradient between northern and southern China.


2018 ◽  
Author(s):  
Haiwei Zhang ◽  
Hai Cheng ◽  
Yanjun Cai ◽  
Christoph Spötl ◽  
Gayatri Kathayat ◽  
...  

Abstract. The collapses of several Neolithic cultures in China are considered to have been associated with abrupt climate change during the 4.2 ka event (4.2–3.9 ka BP). The hydroclimate of this event in the monsoonal region of China, however, is still poorly known, except for a few published stalagmite records from the lower reaches of Yangtze River. In this study, a high-resolution record of monsoon precipitation between 5.3 and 3.6 ka BP based on a stalagmite from Shennong cave, Jiangxi Province, southeast China, is presented. Coherent variations in δ18O and δ13C reveal that the climate in this part of China was dominantly wet between 5.3 and 4.5 ka BP and mostly dry between 4.5 and 3.6 ka BP, interrupted by a wet interval (4.3–4.05 ka BP). A comparison with other records from monsoonal China suggests that monsoon precipitation decreased in northern China but increased in southern China during the 4.2 ka event. We propose that the weakened East Asian summer monsoon controlled by the reduced Atlantic Meridional Overturning Circulation resulted in this contrasting distribution of monsoon precipitation between north and south China. During the 4.2 ka event the rain belt remained longer at its southern position, giving rise to a pronounced humidity gradient between northern and southern China.


2021 ◽  
Vol 7 (23) ◽  
pp. eabg3848
Author(s):  
Steven C. Clemens ◽  
Masanobu Yamamoto ◽  
Kaustubh Thirumalai ◽  
Liviu Giosan ◽  
Julie N. Richey ◽  
...  

South Asian precipitation amount and extreme variability are predicted to increase due to thermodynamic effects of increased 21st-century greenhouse gases, accompanied by an increased supply of moisture from the southern hemisphere Indian Ocean. We reconstructed South Asian summer monsoon precipitation and runoff into the Bay of Bengal to assess the extent to which these factors also operated in the Pleistocene, a time of large-scale natural changes in carbon dioxide and ice volume. South Asian precipitation and runoff are strongly coherent with, and lag, atmospheric carbon dioxide changes at Earth’s orbital eccentricity, obliquity, and precession bands and are closely tied to cross-equatorial wind strength at the precession band. We find that the projected monsoon response to ongoing, rapid high-latitude ice melt and rising carbon dioxide levels is fully consistent with dynamics of the past 0.9 million years.


2018 ◽  
Vol 31 (14) ◽  
pp. 5485-5506 ◽  
Author(s):  
Zhiqi Zhang ◽  
Xuguang Sun ◽  
Xiu-Qun Yang

Abstract East Asian summer monsoon precipitation (EASMP) features complicated interdecadal variability with multiple time periods and spatial patterns. Using century-long datasets of HadISST, CRU precipitation, and the ECMWF twentieth-century reanalysis (ERA-20C), this study examines the joint influence of three oceanic interdecadal signals [i.e., Pacific decadal oscillation (PDO), Atlantic multidecadal oscillation (AMO), and Indian Ocean Basin mode (IOBM)] on the EASMP, which, however, is found not to be simply a linear combination of their individual effects. When PDO and AMO are out of phase, the same-sign SST anomalies occur in the North Pacific and North Atlantic, and a zonally orientated teleconnection wave train appears across the Eurasian mid-to-high latitudes, propagating from the North Atlantic to northern East Asia along the Asian westerly jet waveguide. Correspondingly, the interdecadal precipitation anomalies are characterized by a meridional tripole mode over eastern China. When PDO and AMO are in phase, with opposite sign SST anomalies in the North Pacific and North Atlantic, the sandwich pattern of anomalous stationary Rossby wavenumber tends to reduce the effect of the waveguide in the eastern Mediterranean region, and the teleconnection wave train from the North Atlantic travels only to western central Asia along a great circle route, causing Indian summer monsoon precipitation (ISMP) anomalies. The ISMP anomalies, in turn, interact with the teleconnection wave train induced by the PDO and AMO, leading to a meridional dipole mode of interdecadal precipitation anomalies over eastern China. Through the impact on the ISMP, the IOBM exerts significantly linear modulation on the combined impacts of PDO and AMO, especially over northern East Asia.


2018 ◽  
Vol 45 (15) ◽  
pp. 7711-7718 ◽  
Author(s):  
Richard Ching Wa Cheung ◽  
Moriaki Yasuhara ◽  
Briony Mamo ◽  
Kota Katsuki ◽  
Koji Seto ◽  
...  

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