中国科学院南京地质古生物研究所机构知识库

This paper focuses mainly on the climatic and environmental variations from 8.5 to 3 ka B.P. with particular reference to one stable warmer and wetter millennium (7.2-6 ka B.P.). Some large-scale centennial warming was accompanied by an increase in precipitation owing to the expansion of the monsoon circulation, e.g. rapid warming during the period from 8.5 to 8.3 ka B.P. and was reflected in the high level of some inland lakes and the sudden expansion of vegetation in pollen diagrams. The growth of the Neolithic culture with agriculture and settlement in the present semi-arid area of Northwest China was undoubtedly related to the dramatic warming and wetting before 8 ka B.P. According to the proxy data of palynological studies, the deviation of annual mean temperature from today's about 7-6 ka B.P. was roughly estimated at about 1-degrees-C in South China, 2-degrees-C in the Changjiang (Yangtze) Valley, 3-degrees-C in North China and Northeast China. The strongest warming by 4-5-degrees-C was recorded in Oinghai-Xizang (Tibet) Plateau. The winter temperature rise was much greater than the annual average temperature. In the eastern half of China, the vegetation zones are mainly parallel to the latitude. During the climax of the Holocene warm period, the northern limit of the tropical monsoonal rain forest shifted less than 1-degrees of latitude northward, the subtropical broad-leaved evergreen forest about 1-degrees of latitude, the north subtropical deciduous and evergreen broad-leaved mixed forest about 3-degrees of latitude in the coastal area but only 1-1.5-degrees of latitude in mid-West China and the warm temperate deciduous forest moved 4-degrees of latitude northward, greatly expanding its distribution. Further north, the cool temperate boreal forest withdrew from its southern boundary by about 2-degrees of latitude. Global climatic warming in the mid-Holocene resulted in a sea-level rise. During the period from 6 to 5 ka BP. the sea-level was about 1-3 m higher than the present level. Large area of coastal lowland was submerged by sea water and frequency of occurrence of storm surges also increased during the high sea-level period.