第四纪两类千年尺度气候振荡现象及机理研究

Two types of millennial-scale climate oscillations during the last Quaternary and their triggering mechanism

千年尺度气候突变事件是第四纪冰期普遍存在的气候现象。这些事件可以被分为两类,一类为Dansgaard-Oeschger Event (DO事件),另一类为海因里希(Heinrich Stadial, HS)事件,后者有时也被认为是一种特殊的DO事件,因此也被称为HS-DO事件。HS事件期间北大西洋冰架的融化一般对应DO振荡的冷相位,这与通常认为的冰架在较冷气候下体积增加并不相符。这两类事件在北大西洋重建数据中表现得最为明显,但其气候影响具有全球性。由于没有显著的外强迫驱动这两类气候突变事件,自20世纪90年代首次被确认以来,HS-DO事件一直是古气候界关注的重点,且人们对其触发机理仍没有定论。本文基于目前对这两类千年事件的研究现状,集中总结了目前已有的可反映千年事件的重建数据,利用已有的模拟工作,重点回顾了现有的机制理论,评述了目前研究DO事件以及HS-DO事件的局限性,并对其后续工作,尤其是模拟部分,进行了展望。

Dansgaard-Oeschger events(DO)and Heinrich Stadial(HS)are the most pronounced millennial-scale climate oscillations during the Quaternary.HS,also called HS-DO event,is considered a special DO type in some occasions.Massive ice sheet melting associated with HS occurs during the cold phase of DO cycles,in contradiction to the expectation that ice sheets expand in colder climates and shrink in warmer climates.These events have global climate impacts and thus have been the focus of paleoclimate community for the past several decades,but their triggering mechanism are still under debate.This work summarizes all current available proxy records that contain fingerprints of these abrupt climate oscillations,and discusses limitations in the mechanistic explanations for DO and HS-DO based on current available modeling results,as well as future prospects especially the prospects of modeling these events.