The Pliocene-Pleistocene transition(3.0-2.5 million years ago,Ma)was a critical period during which the Arctic ice sheets expanded extensively and intensified,with the establishment of a permanent ice sheet on Greenla...The Pliocene-Pleistocene transition(3.0-2.5 million years ago,Ma)was a critical period during which the Arctic ice sheets expanded extensively and intensified,with the establishment of a permanent ice sheet on Greenland marking the onset of a bipolar“icehouse”climate state.This interval,characterized by atmospheric CO_(2) concentrations between pre-industrial and modern levels(~280-400 ppmv),provides a critical time window for understanding ice-sheet response to external forcing.Using a high-resolution climate model and a 3D thermomechanical ice sheet model,we simulate the Greenland Ice Sheet(GrIS)volume evolution under different CO_(2) scenarios and analyze its periodic behavior during this period.Our results show that when the GrIS volume was small,its variability was strongly paced by 65°N summer insolation.As the ice sheet grew,its response shifted,becoming increasingly dominated by the obliquity cycle.The GrIS volume reconstruction,consistent with ice-rafted debris records,indicates that after approximately 2.7 Ma,the expanded GrIS exhibited enhanced suborbital to millennial-scale signals and greater ice dynamical variability-a pattern echoing the amplified millennial-scale climate events observed in late Quaternary Greenland ice cores.Furthermore,comparison with deep-sea oxygen isotope records shows that the GrIS began to significantly contribute to the 40,000-year cycle after 2.7 Ma,with its changes slightly leading the signal of the benthic δ^(18)O.This study clarifies the GrIS’s cyclic evolution and constrains its role in the climate system evolution during the Pliocene-Pleistocene transition.展开更多
淮河是一条对华夏文明具有重大意义的河流。但相较于黄河与长江流域,淮河流域的考古及古环境研究较为滞后。桥头遗址是淮河上游一处以石家河文化为主的重要遗址。本研究通过对桥头遗址区及其临近区域的地层调查和室内样品的测试分析,对...淮河是一条对华夏文明具有重大意义的河流。但相较于黄河与长江流域,淮河流域的考古及古环境研究较为滞后。桥头遗址是淮河上游一处以石家河文化为主的重要遗址。本研究通过对桥头遗址区及其临近区域的地层调查和室内样品的测试分析,对该遗址生成前后的环境变化以及古洪水事件与遗址的存续关系等展开了研究。研究发现:桥头遗址生成前大约在8.1~4.6 ka BP(9.1~5.4 cal.ka BP),遗址所在至少方圆2 km的范围区一直被湖沼所覆盖;4.6 ka BP(5.4 cal.ka BP)以后,温暖湿润的气候、地势较高的湖沼相沉积高地以及紧邻作为遗址水源地的母子河等优越的自然环境,吸引了先民来桥头区域生活;4.0 ka BP的气候异常事件、3.5 ka BP(3.9 cal.ka BP)的气候波动所带来的洪水灾害和3.2 ka BP(3.6 cal.ka BP)的淮河改道等自然环境的频繁变动,使得石家河文化以后的1000年时间内遗址区不适宜人类居住。3 ka BP(3.3 cal.ka BP)之后,桥头遗址所在区域的气温逐渐升高变暖,先人再次在此定居;2.5 ka BP(1.8 cal.ka BP)后,气候的剧烈波动、洪水的频繁泛滥再次威胁到人类在桥头遗址区域生产生活,先人从此地再次迁徙。展开更多
基金funded by the Strategy Priority Research Program(Category B)of the Chinese Academy of Sciences(Grant No.XDB0710000)the National Key Research and Development Program(No.2022YFF0801504)+1 种基金the National Natural Science Foundation of China(Nos.42488201,41907371)support from the IGGCAS Key Program(No.IGGCAS-202201).
文摘The Pliocene-Pleistocene transition(3.0-2.5 million years ago,Ma)was a critical period during which the Arctic ice sheets expanded extensively and intensified,with the establishment of a permanent ice sheet on Greenland marking the onset of a bipolar“icehouse”climate state.This interval,characterized by atmospheric CO_(2) concentrations between pre-industrial and modern levels(~280-400 ppmv),provides a critical time window for understanding ice-sheet response to external forcing.Using a high-resolution climate model and a 3D thermomechanical ice sheet model,we simulate the Greenland Ice Sheet(GrIS)volume evolution under different CO_(2) scenarios and analyze its periodic behavior during this period.Our results show that when the GrIS volume was small,its variability was strongly paced by 65°N summer insolation.As the ice sheet grew,its response shifted,becoming increasingly dominated by the obliquity cycle.The GrIS volume reconstruction,consistent with ice-rafted debris records,indicates that after approximately 2.7 Ma,the expanded GrIS exhibited enhanced suborbital to millennial-scale signals and greater ice dynamical variability-a pattern echoing the amplified millennial-scale climate events observed in late Quaternary Greenland ice cores.Furthermore,comparison with deep-sea oxygen isotope records shows that the GrIS began to significantly contribute to the 40,000-year cycle after 2.7 Ma,with its changes slightly leading the signal of the benthic δ^(18)O.This study clarifies the GrIS’s cyclic evolution and constrains its role in the climate system evolution during the Pliocene-Pleistocene transition.
文摘淮河是一条对华夏文明具有重大意义的河流。但相较于黄河与长江流域,淮河流域的考古及古环境研究较为滞后。桥头遗址是淮河上游一处以石家河文化为主的重要遗址。本研究通过对桥头遗址区及其临近区域的地层调查和室内样品的测试分析,对该遗址生成前后的环境变化以及古洪水事件与遗址的存续关系等展开了研究。研究发现:桥头遗址生成前大约在8.1~4.6 ka BP(9.1~5.4 cal.ka BP),遗址所在至少方圆2 km的范围区一直被湖沼所覆盖;4.6 ka BP(5.4 cal.ka BP)以后,温暖湿润的气候、地势较高的湖沼相沉积高地以及紧邻作为遗址水源地的母子河等优越的自然环境,吸引了先民来桥头区域生活;4.0 ka BP的气候异常事件、3.5 ka BP(3.9 cal.ka BP)的气候波动所带来的洪水灾害和3.2 ka BP(3.6 cal.ka BP)的淮河改道等自然环境的频繁变动,使得石家河文化以后的1000年时间内遗址区不适宜人类居住。3 ka BP(3.3 cal.ka BP)之后,桥头遗址所在区域的气温逐渐升高变暖,先人再次在此定居;2.5 ka BP(1.8 cal.ka BP)后,气候的剧烈波动、洪水的频繁泛滥再次威胁到人类在桥头遗址区域生产生活,先人从此地再次迁徙。
