Therefore, hydroclimate conditions in the region during the MCA and LIA were also likely linked to tropical pacific SST variability. Recently, El Niño southern oscillation (ENSO) variability was suggested to have principally driven mid- to late-Holocene climate shift in coastal East Asia 30, 31. This is partly associated with the difficulty to obtain late Holocene sedimentary records with no indication of agricultural disturbance. Even though the hydroclimate history of the last millennium is needed to address such climate crisis issues, it has been rarely reconstructed in coastal East Asia. Coastal cities with fast growing populations are highly susceptible to current warming-induced increases in extreme events such as river floods and storm surges 29. Previous proxy and reviewing studies have so far not seriously examined oceanic forcing 25 despite its significant influence on present East Asia climate 28. In particular, paleoclimate of coastal East Asia cannot be fully understood without exploring oceanic influence. However, substantial areas remain unclearly defined by such a broad classification. East Asia could thus be hydro-climatologically divided into a westerlies-dominated region and a monsoon-dominated region 25. Meanwhile, summer monsoon activity may have been weakened (strengthened) in northern (southern) China by more southerly position of the Inter Tropical Convergence Zone (ITCZ) 25, 26. For example, central Asia and northwestern China were likely wet during the LIA due to reduced solar output and consequent southward migration of westerlies 27. However, inconsistent hydroclimate reconstructions in the region limit an understanding of the mechanisms behind LIA and MCA precipitation 25, 26. It is widely agreed that atmospheric temperatures were relatively low (high) over East Asia during the LIA (MCA) 14, 24. 1350–1850 CE) also has long been investigated because historical documents clearly indicate that its unfavorable climate conditions substantially undermined human societies across the Northern Hemisphere 8, 9, 10.Ī number of paleoclimatological studies have reported East Asian climate variation of the last millennium 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23. 900–1350 CE) to assess the possible outcomes of current global warming 6, 7. Attempts have been made to reconstruct paleoenvironmental history for the medieval climate anomaly (MCA ca. Many paleoclimatologists have been particularly interested in the climate of the last millennium since information regarding past climate is invaluable for predicting future climate changes and its impact on societies 1, 2, 3, 4, 5. Our results additionally imply that SST anomalies in the ETP need to be carefully checked to better understand current hydroclimate variability in coastal East Asia, one of the most populated areas on earth. Therefore, coastal East Asia likely experienced a decline in typhoon-related precipitation during the MCA, in contrast to monsoon-dominated northern China. During El Niño events, the genesis of typhoons affecting coastal East Asia tends to diminish because of warm anomalies of eastern tropical Pacific (ETP) SSTs and downward motions over the western tropical Pacific. Recent paleo-ENSO studies generally support the hypothesis that the MCA was characterized by more persistent El Niño-like conditions. Our results indicate that El Niño southern oscillation-like variations caused the dry MCA/wet LIA pattern in the study area. In this study, we present new high-resolution multiproxy records (diatom, δ 13C, C/N, TS) from the Mulyoungari swamp, Jeju Island, South Korea. Inconsistent reconstructions of East Asian hydroclimate for the last millennium significantly limit our understanding of the mechanisms behind climate variability during the medieval climate anomaly (MCA) and little ice age (LIA) in the region.
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