Wet and cold climate conditions recorded by coral geochemical proxies during the beginning of the first millennium CE in the northern South China Sea. (March 2017)

• Record Type: Journal Article
• Authors: Xiao, Hangfang; Deng, Wenfeng; Chen, Xuefei; Wei, Gangjian; Zeng, Ti; Zhao, Jian-xin
• Is Part Of: Journal of Asian earth sciences. Volume 135(2017)
• Page Start: 25
• Page End: 34
• Publication Date: 2017-03
• Subjects: Eastern Han -- Three Kingdoms -- Western Jin -- Sea surface temperature -- Sea surface salinity -- South China Sea; Earth sciences -- Asia -- Periodicals; Sciences de la terre -- Asie -- Périodiques; Earth sciences; Asia; Periodicals; 555.05
• DOI: 10.1016/j.jseaes.2016.12.012
• Languages: English
• ISSNs: 1367-9120

Abstract

Graphical abstract: Highlights: The climate was cold and wet during 167–309 CE in the northern South China Sea. The cold SSTs were caused by the weak solar irradiance. The wet conditions were caused by the reduced northward shift of ITCZ/monsoon rainbelt. The interannual and interdecadal variability may be associated with ENSO and PDO. Abstract: The past two millennia include some distinct climate intervals, such as the Medieval Warm Period (MWP) and the Little Ice Age (LIA), which were caused by natural forcing factors, as well as the Current Warm Period (CWP) that has been linked to anthropogenic factors. Therefore, this period has been of great interest to climate change researchers. However, most studies are based on terrestrial proxy records, historical documentary data, and simulation results, and the ocean and the tropical record are very limited. The Eastern Han, Three Kingdoms, and Western Jin periods (25–316 CE) cover the beginning first millennium CE in China, and were characterized by a cold climate and frequent wars and regime changes. This study used paired Sr/Ca and δ 18 O series recovered from a fossil coral to reconstruct the sea surface water conditions during the late Eastern Han to Western Jin periods (167–309 CE) at Wenchang, eastern Hainan Island in the northern South China Sea (SCS), to investigate climate change at this time. The long-term sea surface temperature (SST) during the study interval was 25.1 °C, which is about 1.5 °C lower than that of the CWP (26.6 °C). Compared with the average value of 0.40‰ during the CWP, the long-term average seawater δ 18 O (−0.06‰) was more negative. These results indicate that the climate conditions during the study period were cold and wet and comparable with those of the LIA. This colder climate may have been associated with the weaker summer solar irradiance. The wet conditions were caused by the reduced northward shift of the intertropical convergence zone/monsoon rainbelt associated with the retreat of the East Asian summer monsoon. Interannual and interdecadal climate variability may also have contributed to the variations in SST and seawater δ 18 O recorded over the study period.