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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: Age-controlled pollen stratigraphy from the Paju (UJ-10), Cheonggye (Gwangtong Trench-A), and Hanam (UD-2) sites records the response of vegetation to climate changes and human activity over the past 7000 years in the Han River drainage basin, west-central Korea. The pollen profiles show a transition from natural vegetation to human-disturbed vegetation around 4800 cal BP. During the natural vegetation stage (ca. 7000–4800 cal BP; early Neolithic Age), dense woodlands of mixed deciduous and evergreen broadleaved hardwoods flourished in the surrounding hills and mountains owing to the enhanced East Asian summer monsoon. The human-disturbed vegetation stage (ca. 4800 cal BP–modern; late Neolithic Age to modern) was characterized by transitional forests and open grasslands and can be subdivided into several agricultural stages. During the dry-field cultivation stage (ca. 4800–3000 cal BP; late Neolithic to Bronze ages), humans engaged in dry-field agriculture under cool, dry climatic conditions. The ensuing paddy-field cultivation stage (ca. 3000–800 cal BP; since the Bronze Age) initially developed during an interval of stable, warm, wet conditions from ca. 3000 to ca. 1400 cal BP, during which time people of Bronze and Iron Age cultures engaged in widespread paddy farming. Subsequently, a brief climatic fluctuation (ca. 1400–800 cal BP) caused changes in the agricultural practices of the Unified Silla and Koryo people. During the combined dry-field and paddy-field cultivation stage (ca. 800 cal BP–modern; since the Joseon Dynasty), climatic deterioration affected agricultural practices of the Joseon people and resulted in open forests with wide grasslands during the interval equivalent to the Little Ice Age (1550–1859 AD). Since then, humans in the area have strategically managed pine forests to supply wood for house-building and fuel. [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]

Abstract: Marine isotope stage 3 (MIS3), spanning from 25 to 60ka BP, was a time of substantial environmental change that included changes in the global ice volume and atmospheric composition, with resultant regional climate changes. To understand past vegetation responses to such environmental changes in Korea, we estimated the abundance of C3 and C4 plants using the C/N and carbon isotope ratios of sedimentary organic matter. The MIS3 sedimentary unit at the Cheollipo site, located in a western coastal area of Korea, is characterized by a dark to light gray colored sedimentary unit (3.05 to 5.05m in elevation, MIS3), which is between an underlain oxidized yellowish sedimentary unit (<3.05m in elevation) and an overlain oxidized yellowish sedimentary unit (>5.05m in elevation). The estimated abundance of C4 plants varied between 60 and 10% during the MIS3. The suborbital-scale variation in the estimated percentage of C4 plants was similar to those reported in continental ice volume and the East Asian monsoon intensity, suggesting that C4 plants prevailed under colder and drier conditions (intensified winter monsoon), whereas C3 plants have favored a warmer and wetter climate (intensified summer monsoon). Compared with high latitude regions (e.g., Chinese Loess Plateau and Lake Baikal) where low summer temperature suppressed aridity and pCO2 influences during the last glacial period, vegetation change in Cheollipo area may have more sensitively responded to aridity change which had been affected by the summer/winter monsoon intensity. The climate change in the western coastal area (Yellow Sea side) of Korea during the late Pleistocene may have been controlled by regional climate change coupled with continental ice volume change. [ABSTRACT FROM AUTHOR]