"8.2 ka BP冷事件"的研究现状展望

统计了全新世早期气候突变事件"8.2 ka BP冷事件", 并对其触发机制及区域气候响应做了较深入的分析. 从各种气候记录的分布情况来看, 全新世早期的这次冷事件是全球性气候事件, 并非是一种局部气候变冷事件. 全新世早期Agassiz和Ojibway阻塞湖在大约8.47 cal ka BP时突然排泄, 可能是造成8.4～8.0 cal ka BP时期北大西洋地区突然降温的主要原因;另外, 8.4～8.0 cal ka BP期间的太阳辐射量减小或太阳活动减弱, 也可能对全新世早期的这次冷事件有一定强化作用. 由于西风带南移和季风环流减弱等原因的影响, 使得这次冷事件区域气候响应有明显的不同, 欧洲的中高纬度地区、东亚地区呈现一种冷干的气候状态;北美洲三分之二的地区降水量减少、风力加强;中美洲、非洲的大部分地区和阿拉伯半岛均以干旱为主;东欧、地中海地区呈现普遍的冷湿气候环境, 亚马逊盆地、智利玻利维亚高原呈现低湿的气候状况.

Progress of Research on "8.2 ka BP Cold Event"

The "8.2 ka BP cold event" had already been proposed by Beget in 1983, and confirmed further in the study of Greenland ice core. It is clear that the cold event occurred 8.4 to 8.0 cal ka BP, and lasted about 400 hundred years. At that time the lowest temperature had decreased (62) , and was half as large at the Younger Drays deviations. This paper is written based on a review of recent articles and papers, focusing those abrupt climate changes during 8.4~8.0 cal ka BP. It is found that many proxies recorded in ice core, stalagmite, marine and lake sediments indicate the cold event. Appearance of the cold event in the early Holocene is summarized, and its triggering mechanisms and regional climate responses are also discussed. According to the appearance of many kinds of climate records, "8.2 ka BP cold event" was not a local cold event, but a global cold one. Agassiz and Ojibway Lakes draining catastrophically -8.47 cal ka BP might be responsible for the abrupt cold event of 8.4~8.0 cal ka BP in North Atlantic. Furthermore, solar insolation lowing or solar activity weakening around 8.4~8.0 cal ka BP might enhance the cold event. Owing to the westerly wind shifting northward and monsoon weakening, the regional climate response to the cold event is different from place to place: cold and dry in middle and high latitudes in Europe and east Asia; decreased precipitation and increased windiness throughout much of the eastern two-thirds of the United States; arid controlling dominantly the climate in Central-America, Africa continent and Arabia; cooler, wetter conditions occurring generally in eastern Europe and Mediterranean basin; very low effective moisture in the Amazon basin and in the Chilian and Bolivian Altiplano.