第四纪中国热带对全球气候变化的响应

RESPONSE OF QUATERNARY CLIMATE IN TROPICAL CHINA TO THE GLOBAL CHANGE

根据20多个有关沉积、δ18O、孢粉、石笋等分析实例,并与代表全球变化的气候曲线进行对比,认为中国热带万年尺度气候变化的机制,早更新世为轨道驱动,中更新世为季风环流的非轨道驱动,晚更新世为轨道驱动,这个过程与青藏高原隆起的高度和速率有关。晚更新世的千年尺度变化和小冰期的百年尺度变化,其机制是受太阳常数周期性变化的影响。

According to about twenty examples of paleoclimatic analysis the Quaternary climate fluctuation with scales of 10ka,1ka and 100a in tropical China is discussed. As compared with global change, two types of mechanism of climatic fluctuation, which are the orbital drive and non-orbital drive can be deduced. In the period between Pliocene and Pleistocene the climate was transformed from slight change to obvious variation because the Tibetan Plateau uplifted to 1 000m at least at the beginning of Pleistocene resulting in the appearance of monsoon circulation. The δ^(18)O curve of marine oxygen isotope of DSDP607 and that of ODP1143 in the South China Sea are similar to each other showing that the climatic fluctuation was controlled mainly by orbital drive during Early Pleistocene. This was because the Tibetan Plateau uplifted to (2 000)m by 1.1 MaBP but the uplift rate was quite small which was not enough to form strong monsoon circulation at that time. The response of tropical China to the Middle Pleistocene Revolution (MPR) remarked by suddenly cooling can be found also. After the MPR the climatic change during Middle Pleistocene was drived mainly by non-orbital factors because the Tibetan Plateau uplifted rapidly during the period from the end of Early Pleistocene to Middle Pleistocene and strengthened the monsoon circulation. Since Late Pleistocene the climatic variation with scale of 10ka has been controlled by orbital drive because the elevation of Tibetan Plateau and the monsoon circulation have been similar to those at present. Like the global change the climatic change during Late Pleistocene can be divided into four stages in tropical China. In tropical China not only the climate change with scale of 10ka but also that with scale of ka and 100a can be recognized such as the suddenly warming events of Dansgarrd/Oeschger and cooling events of Heinrich in Late Pleistocene as well as the five cooling stages including the Little Ice Age in the historical period since 1kaBC.The mechanism of climate variation with 1ka or 100a scale was probably related to the change of solar constant itself.