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Understanding coastal flooding processes in response to centennial-scale sea-level rise is essential in preparing for the challenge of present-day global warming. Mid-Holocene sea-level rise induced widespread coastal flooding along the East China coast and precipitated the collapse of the Neolithic Liangzhu Culture, the earliest known prehistoric state in East Asia. This paper presents multi-proxy analyses of sedimentology, grain size, total organic carbon (TOC), and alkaline-earth metals extracted by acetic acid (HAc) of a dated sediment core, ZK07, collected from Liangzhu City, with the aim of revealing the detailed progression of coastal flooding phases and the response of prehistoric people at the end of the associated Liangzhu Culture. A three-step succession of coastal flooding processes between ca. 4.6–4.3 cal kyr BP, brought about by relative sea-level rise, is evident in core ZK07. Initially, an increase in the local water level in response to the first phase of sea-level rise is indicated by a gradual increase in TOC at ca. 4630 cal yr BP. Subsequently, at ca. 4520 cal yr BP, a second phase of increased local water-level, consistent with further sea-level rise and salinity intrusion, is suggested by higher Sr concentrations accompanied by a sharp increase in TOC. Thirdly, at ca. 4480–4315 cal yr BP, low TOC content, high - but strongly fluctuating - Sr and Ba concentrations and coarser sediment grain size are all indicative of coastal inundation caused by both storm surges and river flooding associated with typhoon events that correspond with a concurrent phase of accelerated sea-level rise. Considering the evidence of cultural deposits preserved at Liangzhu City, it appears that the Liangzhu people were forced to respond rapidly to the inundation by abandoning the city at ca. 4480 cal yr BP. We suggest that relative sea-level rise and coastal flooding at the terminal stage of the Liangzhu Culture was the regional response to global climate warming and eustatic sea-level rise at that time. Given evidence that a contemporaneous cultural transition took place in the lower Yellow River basin, we further propose that global climate change around 4.5 cal kyr BP had a widespread impact on Neolithic cultural evolution in East China. Furthermore, the rise in local water levels and associated salinity intrusions may be considered as an early warning signal in monitoring future coastal flooding risk. • A three-step succession of coastal flooding was recognized at the end of Liangzhu Culture. • Rise in local water level and salinity intrusion could be early warning of coastal flooding. • Global climate warming and eustatic sea-level rise at ca. 4.5 ka was the major mechanism. • Contrasting Neolithic cultural evolution occurred in the lower reaches of two large rivers in East China. [ABSTRACT FROM AUTHOR]

The paper presents a comprehensive review on lake-level history of Qinghai Lake since marine isotope stage (MIS) 5, after re-examining the sedimentary and geomorphological nature of highstand deposits and re-evaluating the published dating results (318 luminescence ages and 17 14C ages) of shorelines, near shoreline, lacustrine, alluvial, and aeolian deposits. It is concluded that 1) Three lake shoreline sets were classified in the Qinghai Lake Basin with the corresponding elevations of 3220–3260, 3206–3215 and 3194–3205 m. 2) 14C dating on lake sediments is restricted by the upper dating limit of ∼35 thousand years (ka) BP in practice, availability of dating materials and reservoir effect, and that quartz optically stimulated luminescence (OSL) ages older than 80–60 ka may be underestimated while feldspar post-infrared infrared stimulated luminescence (pIRIR) ages could be reliable for dating these older samples. 3) Four highstands were detected by ages. The highest lake-levels at elevations of 3220–3260 m with 26–66 m above the present lake-level occurred in MIS 5, and highstands also occurred in MIS 3 (∼42–38 ka), the last deglaciation (∼16–12 ka), and the Holocene (∼6–5 ka) with similar heights at elevations of ∼3200–3209 m. During the Holocene, lake-levels were relatively low in the early Holocene (∼11–8 ka), increasing substantially after ∼8 ka and reaching the highest lake-levels (elevation of 3203.1 m) at ∼6–5 ka, then decreasing with an interruption by a highstand (elevation of 3202.4 m) at ∼1.8 ka. 4) Shoreline-based lake-level variations are consistent with major climatic proxies (e.g., δ13C org and %thaum) of drilling cores from the lake, regional aeolian activity/pedogenesis and climate change. 5) Compared with the representative lake-levels and moisture records in the Westerlies and East Asia summer monsoon (EASM) dominances, it is suggested that lake-level variations in the southern Qilian Mountains exhibited simultaneity with changes in the intensity of EASM, while those in the northern part were synchronous with the moisture records in arid central Asia, suggesting that EASM did not extend further to the northern Qilian Mountains where the Westerlies prevailed. • Shoreline ages of Qinghai Lake were re-evaluated using multiple dating methods. • Radiocarbon ages saturated at ∼35 ka BP, and quartz OSL at 80–60 ka. • Four lake highstands occurred in MIS 5, MIS 3, last deglaciation, and Holocene. • The Holocene highest lake-levels occurred at ∼6–5 ka, then declined continuously. • Lake-levels in the Qilian Mts were dominated by the EASM in the south, by the Westerlies in the north. [ABSTRACT FROM AUTHOR]

Peatlands are one of the most significant carbon reservoirs in the terrestrial ecosystem. Understanding past peatland carbon accumulation processes and their responses to varying external and internal forcing factors would help reveal the general development patterns of peatland ecosystems and provide useful insights into projecting the fate of carbon reservoirs into the future. In this paper, the basal ages of 17 peat cores were used to explore the lateral expansion processes of the Laolike peatland, northeast China. Two cores were selected to calculate carbon accumulation rates (CAR) and reconstruct moisture/precipitation records based on δ13C and grain size analyses. The basal ages show that the peatland was initiated at 12.1 cal kyr BP, then laterally expanded with its fastest rate occurring during the early Holocene, and reached its largest area around 6 cal kyr BP. The time-weighted mean CAR in the Laolike peatland ranged from 31.1 to 52.9 g C/m2/yr (with an average of 42 g C/m2/yr) during the Holocene. The peatland experienced a high CAR of 52.5 g C/m2/yr from 11.7 to 5 cal kyr BP, followed by a low CAR of 35.1 g C/m2/yr after 5 cal kyr BP. Both lateral expansion and vertical accretion are consistent with the summer insolation, climate seasonality, and the strength of the East Asia summer monsoon (EASM) over multi-millennium timescales, where the CAR correlated well with δ13C and grain size, implying moisture/precipitation might be the primary factors controlling carbon accumulation over millennium timescales. Local conditions, such as topography and hydrology, also played an important role in the process of peatland initiation and lateral expansion, as well as the discrepant CAR within the peatland. This study reveals the roles of climate and local conditions in peatland initiation, expansion, and CAR during the Holocene. In addition, we provide a window for a better understanding of the driving factors of peatland development in the temperate zones of the Northern Hemisphere. • Climate conditions are the primary control on the lateral expansion and vertical accretion of Laolike peatland over multi-millennium timescales. • Moisture/precipitation affects carbon accumulation of Laolike peatland over millennium timescales. • Local conditions play an important role in the lateral expansion and the internal differences of carbon accumulation rate. [ABSTRACT FROM AUTHOR]