中更新世气候转型:特征、机制和展望  

Mid-Pleistocene climate transition: Characteristic, mechanism and perspective

作　　者：王婷 孙有斌[1,3] 刘星星 

机构地区：[1]中国科学院地球环境研究所黄土与第四纪地质国家重点实验室,西安710061 [2]中国科学院大学,北京100049 [3]西安交通大学全球变化研究院,西安710054

出　　处：《科学通报》2017年第33期3861-3872,共12页Chinese Science Bulletin

摘　　要：中更新世转型(mid-Pleistocene transition,MPT)的特征、机理及其影响一直是古气候研究的热点问题之一.通过综合分析全球代表性的地质记录,揭示出海洋和陆地气候变化在中更新世(距今~1.2至~0.7 Ma)多表现为从准4万年到准10万年的主导周期转型,但低纬地区水文气候的周期变化不显著.数值模拟研究表明,地球轨道参数变动引起的太阳辐射变化可能是冰期-间冰期气候旋回的根本驱动,而下垫面和大气CO2浓度变化的反馈机制则触发了中更新世气候周期转型并放大冰期-间冰期的波动.因此,MPT是地球气候系统内外部多个因素共同作用的结果.未来研究一方面应加强中低纬地区水文循环变化研究,关注中更新世气候转型影响的区域差异;另一方面通过整合气候重建和模拟结果,辨析区域气候变化响应差异的主要诱因.Milankovich theory suggested that orbitally induced summer insolation change at high-latitude region of Northern Hemisphere played a key role in driving the ice cycles during the Pleistocene. However, a significant shift of the Pleistocence climate from 41-ka to 100-ka cycles （namely mid-Pleistocene transition, MPT） cannot be simply attributed to the astronomical forcing due to insignificant insolation change induced by eccentricity forcing. Here we summarized multiple proxies generated from the ocean and land to address Pleistocene climate changes such as global ice volume, sea surface temperature, sea level, aridity of dust sources, and monsoon-related hydrological cycles. The temporal and spatial characteristics of the MPT phenomenon, in terms of the timing, duration, ampli- tudes and frequencies, were addressed using spectral and wavelet results. Most records reveal that the MPT was commenced as the onset of the -100-ka cycles at -1.2 Ma, and ended by the establishment of the dominant 100-ka cycles at ~0.7 Ma. However, some hydroclimatic proxies from the Mediterranean Sea, South China Sea and Chinese caves show a relatively strong 23-ka cycles during the middle to late Pleistocence. Such a difference may be at- tributable to varied sensitivity of proxy indicators to the insolation and glacial forcing. Globally, temperature and sea level signals that are affected by changing ice volume usually demonstrate a distinctive and consistent MPT. By contrast, regional hydroclimatic proxies at mid-to-low latitudes are likely dominated by the precession cycles （i.e. high-resolution, absolutely dated Chinese speleothem records）. The MPT associated with the onset of -100-ka cycles has inspired the paleocommunities to address its driving mechanism from both data and model perspectives. Several hypotheses have been proposed to explain the MPT in the past two decades, including nonlinear response to external forcing and complicated internal feedbacks. The nonlinear response to the astronomical forcing including ecce

关 键 词：中更新世转型(MPT) 冰期-间冰期旋回 轨道要素 气候系统反馈 水文过程 

分 类 号：P532[天文地球—古生物学与地层学]