Last glacial maximum in China: comparison between land and sea

Abstract

As a result of the sea-level drop at the last glacial maximum (about 100–120 m in the South China Sea, and 130–150 m in the East China Sea), the size and configurations of the China Seas changed greatly. The East China Sea with the Yellow Sea and Bohai Gulf was reduced into an elongated trough, while the South China Sea became a semi-enclosed gulf. Due to the southern shift of the polar front in the North Pacific and the reorganization of the surface current system, the winter temperature in the South China Sea was 6–10°C colder, and the seasonality was much stronger than it is now. The reduced sea area, and thus the increased distance to the coast, together with the declined sea surface temperature, led to intensified aridity on the land. The enhanced eolian processes related to the intensification of the winter monsoon caused an expansion of the loess deposition area reaching the southeastern part of China to the south of the Yangtze River and off the modern sea coast. Vegetation zones greatly shifted to the southeast. In north China, deserts and steppes were much more extensive than they are now and the modern areas of warm-temperate, broad-leaved forests were occupied by steppes or woodland. In south China, the deciduous, broadleaved forests were developed in areas now covered by evergreen forests, and the monsoon rain forest completely disappeared. The changes in the climate on land and the configurations of seas altered the sediment supply and sedimentation rate in the China Seas, giving rise to the Atlantic-type late Quaternary CaCO 3 curve there.