| 1. |
- Gao, Fuyuan, et al.
(författare)
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Rapid retreat of the East Asian summer monsoon on the western Chinese loess Plateau during the middle to late Holocene and its environmental and societal implications
- 2023
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Ingår i: Catena (Cremlingen. Print). - 0341-8162 .- 1872-6887. ; 231
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Tidskriftsartikel (refereegranskat)abstract
- Spatiotemporal changes in the Holocene climate of the arid region of China were principally caused by shifts in the intensity and location of the East Asian summer monsoon (EASM). However, our knowledge of these EASM variations is limited, especially since the middle Holocene. We investigated two aeolian sedimentary sections (the Linxia/LX and Gulang/GL sections) on the western Chinese Loess Plateau (CLP), to explore the variations in the intensity and location of the EASM and their impact on the regional environment and human cultural development during the middle to late Holocene. The longitudes of these two loess sections are similar, but the GL section is located on the northern edge of the CLP, in the eastern Hexi Corridor, and it is situated further north than the LX section. The chronologies of both sections are based on accelerator mass spectrometry C-14 dating, and environmental magnetic parameters and grain size end-members were used to reconstruct their moisture histories. The results suggest that the climate at the LX section was relatively dry before 3.5 ka, after which it became wetter. In contrast, at the GL section, the climate was also relatively dry before 3.5 ka, with the wettest conditions occurring during 3.5-2 ka, but subsequently there was an abrupt shift to a dry climate. We suggest that these spatiotemporal patterns reflect the westward movement and rapid southward retreat of the EASM and the linked monsoon rainfall belt. TraCE-21 ka climate simulation results support our inference. We also found that, compared with other ancient cultures in the eastern Hexi Corrido, sites of the Shajing culture, dated to similar to 2.4-2.8 ka, are predominantly located in areas that are arid at the present-day, and relatively distant from rivers. We suggest that this distribution pattern reflected the occurrence of a humid climate during the period of the Shajing culture, thus demonstrating the impact of the EASM on cultural development in this region.
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| 2. |
- Li, Guoqiang, et al.
(författare)
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Differential ice volume and orbital modulation of Quaternary moisture patterns between Central and East Asia
- 2020
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Ingår i: Earth and Planetary Science Letters. - : Elsevier. - 0012-821X .- 1385-013X. ; 530
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Tidskriftsartikel (refereegranskat)abstract
- Desertification is of pressing environmental concern in large parts of Asia and directly affects millions of people. Arid Central Asia (ACA) in particular is highly sensitive to desertification and environmental change. Climate change in ACA may be driven by westerly circulation or monsoon variation. However, no consensus exists over their relative importance during the Quaternary and this greatly restricts our understanding of how this region may be affected by future climate change. Here we use the most detailed luminescence dating age model yet produced for ACA for three loess records in the Tianshan Mountains spanning the past 250 ka to show a sharp dichotomy in moisture variation between lowland and high mountain areas. The lowland areas of ACA are subjected to persistent aridity during past 250 ka, while highland areas clearly show dry-glacial and moist-interglacial changes, synchronous to moisture variability in monsoonal East Asia, and both co-varying with global ice volume and greenhouse gas (GHG) variation. In contrast, moisture variability across ACA within interglacials varies inversely with insolation-driven precessional changes. This is directly out of phase with the moisture changes of East Asia, which co-vary with precessional insolation changes, and indicates the influence of Westerly circulation in ACA. Our Flexible Global Ocean-Atmosphere-Land System model simulations further reveal that coupled ice volume and GHG variations dominated climatic variability in both ACA and East Asia over glacial-interglacial cycles. However, the out of phase relationship between the intensity of the Westerly and East Asian monsoon systems during interglacial periods indicates that precessional forcing is responsible for differences in moisture patterns between ACA and East Asia. These observations indicate that moisture levels will not increase even in high altitude regions of ACA over the next several millennia; rather desertification is likely to worsen resulting from stabilization of the Westerlies as a result of low summer insolation.
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| 3. |
- Yang, Junhuai, et al.
(författare)
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Holocene forcing of aeolian dust activity over the Tibetan Plateau and its surroundings
- 2024
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Ingår i: Global and Planetary Change. - 0921-8181 .- 1872-6364. ; 235
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Tidskriftsartikel (refereegranskat)abstract
- Aeolian deposits on the Tibetan Plateau (TP) and its surroundings provide crucial source materials for the Asian dust cycle, which significantly affects Asian and global ecosystems and climate. However, it is unclear how the dust dynamics of the TP and its surroundings are linked to Earth's climate system. To address this issue, we examined the grain size and accumulation rate of six Holocene aeolian sections on the southern TP (a new, well-dated high-resolution section, two relatively low-resolution sections, and three published sections) and combined them with equivalent aeolian sedimentary records from eastern arid central Asia. The results suggest that dust activity in both regions decreased during the early to middle Holocene and then increased in the late Holocene. We hypothesize that the primary drivers of Holocene dust activity in both regions are similar. Cold-season insolation, as the primary driving factor, combined with ice volume and atmospheric CO2 concentration, collectively controlled the regional temperature, which determined the near-surface wind intensity via its influence on the TP High and Siberian High, respectively, thus ultimately controlling the regional dust activity. In this context, we project that dust activity on the TP and its neighboring areas will decrease under warm scenarios in the 21st century. Overall, our findings provide an extensive overview of the past, present, and future scenarios of Asian dust activity, especially of the TP dust.
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