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The climate change on the Tibetan Plateau (TP) exhibits a north-south dipole trend during the Holocene. However, it is unclear whether regional differences exist in the variations and driving mechanisms of dust storm activities across the entire TP, and whether these mechanisms align with those found in monsoonal northern China. Here, we present a high-resolution Holocene record of dust storms from an undisturbed lake in the research gap area of the TP, and compile previously published records from other TP regions. Our findings indicate that the dust storm activity increased from the early Holocene to the late Holocene, peaking after 5 cal ka BP. Importantly, our comparison with other dust storm records reveals a unified intensification of dust storm activity across the entire TP during the late Holocene, a pattern distinctly different from the north-south dipole trend of precipitation variation. Moreover, this unified pattern of dust storm intensification across the TP cannot be explained by the decreasing intensity of the East Asian winter monsoon (EAWM) during the Holocene. The observations suggested a limited role for precipitation and EAWM in modulating TP dust storms on the millennial timescale during this period. By contrast, the increases in dust storms on the TP after 5 cal ka BP correlates well to the southward shift of the westerly jet driven by the North Atlantic Oscillation (NAO). As the NAO transitioned to a negative phase during the late Holocene, a meandering westerly jet shifted southward to the interior of the TP, intensifying wind intensity and leading to dust storm outbreaks. • Holocene dust storm record in the crucial research gap area of the Tibetan Plateau (82 characters). • A spatial consistency in Holocene dust storm changes over the entire Tibetan Plateau (84 characters). • Low frequency of dust storm activity during the early and middle Holocene (73 characters). • Southward shift of the westerly drove dust storm outbreaks during the late Holocene (83 characters). [ABSTRACT FROM AUTHOR]

The lower Yangtze is one of the regions of origin of rice agriculture but it is unclear if environmental change drove the transition from hunting-gathering to agriculture. Long-term and continuous lacustrine records of anthropogenic fire are a more effective means of addressing this problem than the fragmentary terrestrial records available for the lower Yangtze region. We constructed a Holocene fire history revealed by records of black carbon content (BCC) and grain size of the sediments of Lake Nanyi in the lower Yangtze. Our results show the following: 1) Peaks in fire activity occurred during ∼8400–6500 (fire peak P1) and ∼ 1100–0 cal BP (fire peak P2), while weaker fire activity occurred during ∼6500–1100 cal BP (S2). 2) This temporal pattern of fire activity, with a double peak (P1-S2-P2), was asynchronous from east to west across the lower Yangtze. The warm and humid climate would not have caused intense fires and the reduction of forest during ∼8400–6500 and ∼ 1100–0 cal BP. Therefore, we suggest that anthropogenic ignitions, corresponding to pronounced population fluctuations after 8400 cal BP, dominated the regional fire activity. Combined with archaeological evidence, the inverse relationship between the agricultural and population levels and fire intensity during the mid-Holocene suggests that fire intensity at this time was the result of the diversity of landscape types associated with prehistoric subsistence patterns, rather than the magnitude of anthropogenic activity. Combined with sea level, rainfall and archaeological evidence, we propose a mechanism whereby asynchronous water-level rise during ∼8400–6500 cal BP forced the migration of humans to the foothills where they often used fire to modify the landscape as part of a broad-spectrum subsistence pattern. Whereas, water-level fall after 6500 cal BP expanded the area of open ground for human settlement, and in this less diverse landscape, less use was made of fire in agricultural subsistence. Overall, our study reveals how regional water-level, driven by sea-level rise and extreme rainfall, delayed the transition from hunting-gathering to agriculture in the lower Yangtze region. • The Holocene fire history representing the lower Yangtze area is reconstructed. • Paleofire in the lower Yangtze area peaked during ∼8400-6500 cal BP and 1100-0 cal BP. • Increased burning of forests by human-induced fire peaks in the lower Yangtze area. • Prehistoric subsistence regimes dominated the burning strategy in the lower Yangtze area. • Rising water level delayed the emergence of prehistoric agriculture in the lower Yangtze area. [ABSTRACT FROM AUTHOR]

The Tibetan Empire, the only united regime in Tibetan history, existed between 618 and 877 CE, when Tibet was a unified world power, contesting control of Central Asia with the Tang Empire and the Abbasid Caliphate. Before its collapse in the 9th century, this was the world's highest elevation empire, ruling a vast territory that extended well beyond the Tibetan Plateau. However, factors leading to the rapid decline of this powerful highland empire remain elusive. Here we use a highly resolved lake sediment record from the western Tibetan Plateau to demonstrate that pronounced fluctuations in the climate regime between the 7th and 9th centuries played a key role in the fragmentation of the Tibetan Empire. Specifically, we demonstrate that a nearly complete shift from planktonic to benthic diatom life strategy signified markedly drier conditions and lower lake-levels. The height of the empire's power (ca. 600–800 CE) coincided with two centuries of uncharacteristically warm and humid conditions, whereas the empire's collapse (ca. 800–877 CE) co-occurred with an abrupt onset of severe drought conditions that were clearly registered in the paleolimnological records. Severe drought conditions combined with decreased social resilience might have led to rapid declines in crop production, which fostered a surge in domestic conflicts and expediated the final collapse of the Tibetan Empire. Although religious and political factors are commonly cited to explain the fall of this formidable great power, our paleoenvironmental analyses underscore that harsh environmental factors might have hastened the cultural decline of this highland region. • Paleolimnological data from a rare freshwater lake in the western Tibetan Plateau. • Abrupt collapse of the Tibetan Empire around 9th century linked to severe drought. • Rise and fall of empire linked to marked climate shifts between 7th and 9th centuries. • These changes were detrimental to the political unity of the Tibetan Plateau. • Diatoms closely tracked changes in lake level. [ABSTRACT FROM AUTHOR]