Abstract

Holocene abrupt cooling events have long attracted attention in academia due to public concern that similar rapid changes may reappear in the near future. Thus, considerable progress has been made toward understanding these short-term cooling events in the Northern Hemisphere, particularly in Europe and North America. However, few relevant studies have been conducted in coastal East Asia due to a lack of undisturbed sample materials appropriate for paleoclimate studies. In this study, we examined Holocene abrupt drying events and the Holocene climate optimum (HCO) based on a new high-resolution multi-proxy record (pollen, mean grain size, total organic carbon, carbon/nitrogen ratio) from the south coast of Korea. Possible cultural impacts of the events were also explored using summed probability distributions (SPDs) of archaeological radiocarbon dates. Our arboreal pollen percentage (AP) data clearly indicated drying events centered at 9.8 ka, 9.2 ka, 8.2 ka, 4.7 ka, 4.2 ka, 3.7 ka, 3.2 ka, 2.8 ka, and 2.4 ka BP. The AP data also indicated that forests were severely damaged by a two-step successive drying event during the period from 8.4 ka to 8 ka BP and that the HCO lasted from ca. 7.6 ka to ca. 4.8 ka BP. According to the results of a correlation analysis, climate variations on the Korean peninsula were possibly controlled by shifts in western tropical Pacific (WTP) sea surface temperatures during the past ~5500 years. Simultaneous declines in the SPDs and AP from 2.8 ka to 2.3 ka BP may reflect a demographic reduction attributable to rapid climate deterioration on the peninsula. Refugee agriculturalists might have immigrated to Japan and developed the Yayoi culture. In this study, the 2.8 ka event and its societal impact are recognized clearly for the first time in coastal East Asia.

Highlights

  • Holocene abrupt cooling events have been vigorously investigated due to concerns that rapid shifts may appear again in the future[1,2]

  • We investigated Holocene abrupt cooling events and the Holocene climate optimum (HCO) based on a new high-resolution multi-proxy record from the south coast of Korea

  • 1) Our pollen records (AP values) clearly demonstrate drying and/or cooling events centered at 9.8 ka, 9.2 ka, 8.2 ka, 4.7 ka, 4.2 ka, 3.7 ka, 3.2 ka, 2.8 ka, and 2.4 ka BP

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Summary

Introduction

Holocene abrupt cooling events have been vigorously investigated due to concerns that rapid shifts may appear again in the future[1,2]. The dynamics that underpin the spatial and temporal differences in the Holocene EAM variability are still not clearly understood[11,12,17,18,19], and further investigation is www.nature.com/scientificreports/. The detailed mechanistic explanation of short-term Holocene cooling events is apparently incomplete in East Asia as the underlying causes behind them are too complicated to be clearly identified. Abrupt Holocene cooling events in the NH are believed to have been caused by many different factors, for example, variations in the Atlantic meridional overturning circulation (AMOC), tropical Pacific sea surface temperature (SST), volcanic activity and sunspot activity. Cave stalagmite δ18O records from inland China are detailed enough to investigate the timing and structure of abrupt Holocene climate events, and δ18O data with sound chronologies and high temporal resolutions provide reliable and useful paleoclimate information. As many local records as possible are needed to better understand the causes of abrupt climate shifts and to assess the societal response more accurately

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