中国全新世4.2ka BP气候事件及其对古文明的影响

Records of 4.2 ka BP Holocene Event from China and Its Impact on Ancient Civilizations

利用近年来发表的全新世高分辨率古气候记录,如湖泊、泥炭、石笋及其他古气候地质载体记录,对4.2ka BP气候突变事件在中国的表现进行了分析,认为该气候事件在中国普遍表现为干旱,伴随部分地区的降温,体现了东亚地区对全球4.2ka BP气候事件的响应。结合考古学研究成果,认为这一气候事件所导致的中国北部大范围、持续性的干旱,是造成中国北部新石器文化衰落的主要原因;所导致的南部持续干旱、局部频繁洪涝,以及气候剧烈频繁的波动,是造成中国南部新石器文化衰落的主要原因。对于该气候事件的触发机制,洋流变化的贡献很可能小于大气环流变化的贡献。太阳辐射减弱造成的北半球降温所引起的半球间洋面温度梯度的变化,可导致赤道辐合带(ITCZ)南移,并使得北半球中低纬度地区季风减弱;同时季风与厄尔尼诺-南方涛动(ENSO)间的相互作用可进一步诱发季风突变,造成北半球中低纬度地区大面积干旱。

Recent published high resolution records of the 4.2 ka BP event from lake sediments, peats, sta- lagmites and other geological paleoclimate archives from China have been presented in this paper, which suggests that there was a sever drought across most areas of China with a temperature decrease in a few lo- cations during 4.2 ka BP period. The 4.2 ka BP records from China show the response to the global abrupt climate change. Combined with archaeological records in China, the persistent and widespread drought during 4.2 ka BP is supposed to be the main potential factor causing the sudden collapse of Neolithic civili- zations in North China, and also the main reason for the collapse of Neolithic civilizations in South China with local frequent flooding and climate fluctuation. Rather than the ocean circulation, the ocean--atmos- phere system might play a more important role in this event. The Northern Hemisphere cooling caused by reduced solar output during 4.2 ka BP could lead to the change of interhemispherie thermal gradient, resul- ting in Intertropieal Convergence Zone （ITCZ） shifting southwards and the low-latitude monsoon weake- ning . In addition, the interaction between the monsoon and EI Nifio-Southern Oscillation （ENSO） could strengthen the monsoon abrupt change, leading to the widespread drought across low-latitude areas.