East Asia Winter Monsoon changes inferred from environmentally sensitive grain-size component records during the last 2300 years in mud area southwest off Cheju Island,ECS

The last 2000 years are an important time span both for IGBP-PAGES and CLIVAR of WCRP. One of the main aims of these projects is to obtain high-resolution records of global change, such as that stored in ice cores, tree rings, speleothems, corals, lakes, marine records, etc., and then use these data to make sound estimates for future global change. To accomplish these projects, we first need to obtain high-resolution geological records and proxies for climatic/environ- mental changes. …

East Asia Winter Monsoon changes inferred from environmentally sensitive grain-size component records during the last 2300 years in mud area southwest off Cheju Island, ECS

Environmentally sensitive grain-size component (ESGSC) extracted from grain-size data of a sediment core B2, which were retrieved from mud area southwest off Cheju Island (MACI), East China Sea (ECS), can be used to indicate the variations of East Asia Winter Monsoon (EAWM), with high (low) content/mean-size of ESGCS denote to strong (weak) EAWM. Combined with AMS¹⁴C datings core B2 provides a continuous high-resolution record of EAWM changes over the past 2300 years, with an average resolution of 13 years. The results show that the variations of EAWM are consistent with temperature changes inferred from historical documents in eastern China over the past 2300 years, from which four climate stages may be identified. In stages before 1900 aBP (50 AD) and 1450–780 aBP (50–1170 AD) the EAWM were comparatively weak, corresponding to warm climate periods in eastern China, respectively. And in stages of 1900–1450 aBP (50–500 AD) and 780–219 aBP (1170–1731 AD) the EAWM were strongly developed, which correspond well to climate changes of two cold periods in eastern China. It is also shown from this study that the stage at 780–219 aBP (1170–1731 AD) was the coldest climate period during the last 2300 years and could be, therefore, related to the Little Ice Age (LIA). Climatic fluctuations appeared obviously in all the four stages, and two climate events of abrupt changes from warm to cold occurred at around 1900 aBP (50 AD) and 780 aBP (1170 AD), of which the latter is probably related to globe-scale changes of atmospheric circulation at that time.