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Projections indicate increasing coastal hazards in the Yellow Sea region owing to relative sea-level rise. Accordingly, regional studies of such change over the Holocene timescale could be helpful in mitigating these threats. Here, we describe the Holocene record of relative sea-level change in the Gochang-Yeonggwang area of South Korea. We compared this record with that of other sites around the coast of the Yellow Sea, including Bohai Bay (China), the Tando Estuary and Gunsan Bay (South Korea), and sites on the east coast of the South Sea and Toyo-oka Basin, Japan. The findings are based on a multi-proxy study, including lithostratigraphy combined with radiocarbon dating and analyses of grain size distribution, magnetic susceptibility, and geochemistry, which facilitated the generation of 89 paleo-sea-level points reconstructed from 28 borehole cores. The early Holocene transgression was found to start later at Gochang-Yeonggwang than at Gunsan Bay, although the distance between them is only 150 km. This result was inferred from substantial differences in sediment delivery owing to Holocene differences in river basin size, topography, and tectonic context. Before ∼7 ka, the slope and highstands from the predicted mean sea-level models at Bohai Bay, Tando Estuary, and Gochang-Yeonggwang were steeper and lower, respectively, from north to south in the Yellow Sea, approaching the slope of the glacio-eustatic sea-level curve. Therefore, the levering effect of transgression in the early Holocene decreased southward in the Yellow Sea. The slight fluctuation in mean sea-level points of the late Holocene resulted from the formation of storm deposit layers in the coastal area, erosion and redeposition in the channel, and geomorphic effects. A partial difference occurred between the relative sea levels at Gochang-Yeonggwang and Toyo-oka. Future relative sea-level research at the southernmost part of the east coast of the Yellow Sea would further improve understanding of the coastal evolution of the region. • The RSL curve slope at ∼8 ka was the steepest among the Yellow Sea east coast sites. • Highstand on RSL is lower than any other east coast site of the Yellow Sea. • Early Holocene transgression levering effect decreased southern of the Yellow Sea east coast. • RSL in the late Holocene was influenced by glacio-eustatic sea-level change. [ABSTRACT FROM AUTHOR]

This study reconstructs a record of typhoon frequency over the Korean Peninsula during the mid-Holocene using mineral components and diatom assemblages in deposits of Lagoon Hyangho, located on the east coast of the peninsula. The lagoon deposits confirm the occurrence of cyclical, multi-centennial scale episodes of low salinization induced by typhoon-derived heavy rain. Although shifts in typhoon frequency broadly follow El Niño/Southern Oscillation (ENSO) conditions during the Holocene, evidence from the typhoon-induced deposits in Hyangho Lagoon suggests that the path of the polar westerly jet controls the effect of ENSO on multi-centennial-scale typhoon patterns across the mid-latitude region of East Asia. The influence of ENSO is limited when the westerly jet passes through low latitudes. Fluctuations in solar activity play a key role in regulating movement of the westerly jet. Multi-centennial scale changes in typhoon frequency in mid-latitude East Asia are, therefore, influenced by changes in solar activity and ENSO conditions. [ABSTRACT FROM AUTHOR]

To trace the surficial responses of lowlands to past climate change, we investigated δ 13 C in total organic carbon (TOC), C/N ratios, magnetic susceptibility (MS), and silicon (Si) intensity (directly proportional to concentration) in wetland sediments collected from the Gimpo area of central Korea, covering 6600–4600 cal yr BP. Two organic layers with high TOC%, negatively depleted δ 13 C TOC values (− 27 to − 29‰), low MS values, and low Si intensities were found at 6200–5900 and 5200–4800 cal yr BP, respectively. These middle Holocene wet periods corresponded to relatively intensified summer monsoon and solar activity periods. The intervening dry period (5900–5200 cal yr BP) with high MS, high Si, and low TOC% corresponded to an intensified dust-activity interval and stronger winter monsoon. This multi-centennial climatic fluctuation of wet periods (6200–5900 cal yr BP and 5200–4800 cal yr BP) and an intervening dry period (5900–5200 cal yr BP) in central Korea was more synchronous with climate change in the arid inner part of China than with that in South China, suggesting possible strong high-latitude-driven climatic influences (e.g., North Atlantic cooling events) during the middle Holocene. [ABSTRACT FROM AUTHOR]

Abstract: A 9.35-m long sediment core, CK2, that covers the time span between 31.98 and 9.14 kilo annum before present (ka BP) at the Luobei Depression (Lop Nur, Eastern Xinjiang, Northwest China) was studied by pollen analysis. The pollen assemblages of coniferous trees, temperate deciduous trees, herbs, and shrubs can be divided into the following four stages: Zone I (31.98ka BP to 19.26ka BP) corresponds to a steppe or desert steppe landscape, which conforms to the cold-wet climatic environment of the Last Glacial Maximum; Zone II (19.26ka BP to 13.67ka BP) corresponds to a steppe–desert or desert landscape, which conforms to the warm-arid climatic environment of the transient interglacial period; Zones III (13.67ka BP to 12.73ka BP) and IV (12.73ka BP to 9.14ka BP) are similar to Zones I and II, respectively, corresponding to the late last glacial and post last glacial, i.e., Early Holocene, respectively. The climatic environment in Lop Nur was increasingly getting drier based on Artemisia/Chenopodiaceae ratios of ≤0.5 in Subzones IVa and IVc. The Heinrich cold events (H3, H2, H1, and YD) and the Dansgaard–Oeschger warm events (IS4, IS3, IS2, IS1) with millennial-scale changes appearing at high latitudes can also be found in the pollen records of Lop Nur. Results show that the climate characteristics of the Lop Nur region are mainly controlled by the westerly belt, as displayed in mainly cold-wet or warm-arid synchronization. These climate characteristics differ from those of the monsoon area, which are mainly displayed in cold-arid and warm-wet synchronization but also restricted by the atmospheric circulation at high latitudes. [Copyright &y& Elsevier]

This study traces coastal sand dune development processes in East Asia during the Holocene to understand climate and environmental changes. We used optically stimulated luminescence (OSL) dating to examine periods of activation and stabilization of dunes along the western coast of the Korean Peninsula. The results from the Taean Chollipo, Seocheon Dasari, and Gochang Sabanri dunes were then compared with those from previous studies to establish a broad understanding of coastal dune development in this region. Sedimentation rates were calculated for the three dunes, and their development periods were classified through statistical analysis that included data from previous studies. We defined five main periods of late Holocene dune development (<0.1 ka, 0.2–0.5 ka, 1.2–2.0 ka, 2.5–3.2 ka, and 5.5–6.5 ka). These correlated to periods of sea level decrease and global cooling determined by ice rafted debris records. We concluded that the development of coastal dunes in western Korea was influenced by sea level decreases, and global cooling events were enhanced by the East Asian winter monsoon. In addition, human activity increases also contributed to the development of the dunes. This study showed how coastal sand dunes can be evaluated as important indicators of global climate change. These results improved our understanding of how paleoclimate changes affected environmental conditions in East Asia and how coastal dune development periods can be used to reconstruct paleo-environmental conditions. • Coastal sand dunes are developed along the western coast of the Korean Peninsula. • Five main periods of late Holocene dune development were determined by OSL. • Main periods were -less than 0.1, 0.2–0.5, 1.2–2.0, 2.5–3.2, and 5.5–6.5 ka. • Main periods were agreed with sea level decrease and global cooling in the Holocene. [ABSTRACT FROM AUTHOR]

To trace the environmental change that occurred at a coastal area during the Holocene, we performed radiocarbon dating and geochemical analyses using sedimentary cores recovered from the Beolgyo tidal flats on the south coast of Korea. The δ 13 C values of total organic carbon (TOC), which represent relative inputs of terrestrial (or freshwater) and marine organic sources, revealed a long-term increasing trend from −27.5 to −21.7‰ during the period between 10,000 and 3000 cal BP, suggesting an evolutionary series of fluvial-dominant to marine-dominant environments, coupled with weakened summer monsoon intensity. From 3000 cal BP to the present, the δ 13 C TOC decreased gradually from −21.7 to −24‰, indicating enhancement of freshwater input during this time. The observed long-term environmental change was divided into six stages based on the averages of the total sulfur content (TS%) and the organic carbon to sulfur ratio (C/S), proxies for paleosalinity. On multi-centennial to millennial timescales, higher C/S ratios and lower TS% were linked to higher δ 13 C TOC values, indicating strong freshwater input at Stage 2 (∼8300–7400 cal BP), Stage 4 (∼4500–3300 cal BP), and Stage 6 (∼1100 cal BP to present). Strong freshwater discharge events synchronously occurred at 4300 cal BP and 3600 cal BP along the south coast of Korea. Further testing should be carried out in other East Asian coastal areas. This study suggests that sedimentary δ 13 C TOC values and C/S ratios can be used in Asian coastal regions to trace past freshwater input events and summer monsoon intensity during relatively stable sea level periods (e.g., the middle to late Holocene). [ABSTRACT FROM AUTHOR]

To reconstruct environmental change during the late Holocene, we investigated sedimentary δ 13 C values from an exposed section on Geoje Island, on the southern coast of Korea. The δ 13 C values ranged from −24.3‰ to −21.2‰ and were divided into five stages based on the average value (−22.5‰). A comparison with the regional climate index revealed that wet periods linked to intensified summer monsoon conditions occurred at Stage 1 (4500–3600 cal BP), Stage 3 (1350–900 cal BP), and Stage 5 (300 cal BP to present). Dry intervals were found at Stage 2 (3600–1350 cal BP) and Stage 4 (900–300 cal BP). We found two different vegetational responses to changes in regional temperature and summer monsoons. Stage 3, corresponding to the MWP, was characterized by an association between the δ 13 C values on the island and the regional temperature, but Stage 4, including the LIA interval, did not show such a relationship. Furthermore, based on comparison with the summer monsoon index, this study suggested that, on the southern coast of Korea, vegetational change was controlled by an MWP-like mode during the warm and wet periods following regional climate change, whereas a LIA-like mode showing independent climate change was dominant during the cold and dry periods. This difference in vegetational changes along the southern coast of Korea and regional (mainly terrestrial-signal based) climate change may be attributed to the influence of sea surface temperature changes in the tropical ocean through the transport of warming seawater by the Kuroshio and Tsushima currents on the East Asian coastal area, including this study area, than on the inner part of the East Asian continent. [ABSTRACT FROM AUTHOR]