Tropical rainfall variations and human activities of last 1 000 years recorded by lake deposits on the Dongdao Island, Xisha Islands

A series of paleoclimate researches have been made in the South China Sea for the past 1000 years, that provided the insights to the understanding of regional climate change pattern and served as the basis to predict and evaluate the future trends of climate change under the joint actions of the human and the nature. Numerous natural archives and proxies are adopted to reveal the climate changes in different regions of China influenced by monsoon and tropical ocean processes. However, due to the lack of high-resolution climate records, our knowledge about the link between precipitation patterns and monsoon variability remains incomplete, particularly in the tropical region. In order to study the rainfall patterns and the history of anthropogenic activities in tropical zones during the time of AD 1000—1700, we studied such proxies as grain-size distribution and magnetic parameters collected from the sediments of the Cattle Pond on the Dongdao Island of the Xisha Islands. The results show that the precipitation on the Dongdao Island is mainly influenced by ENSO activities and the movements of the Intertropical Convergence Zone. Both of the factors will increase rainfall in the study area, which is opposed to the pattern of the Monsoon system. Human activities on the island were vigorous during the Southern Song Dynasty and the Late Ming Dynasty when the climate is humid and rich in rainfall. There are two periods characterized by sandstorms occurred in northern China during the time of AD 1000—1200 and AD 1450—1600 respectively in the Xisha Islands, reflecting the long-distance migration and precipitation of dust by air.