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The timing and effect of the earliest human arrivals in North America 期刊论文
NATURE, 2020
作者:  Lorena Becerra-Valdivia;  Thomas Higham
收藏  |  浏览/下载:26/0  |  提交时间:2020/08/09

The peopling of the Americas marks a major expansion of humans across the planet. However, questions regarding the timing and mechanisms of this dispersal remain, and the previously accepted model (termed '  Clovis-first'  )-suggesting that the first inhabitants of the Americas were linked with the Clovis tradition, a complex marked by distinctive fluted lithic points(1)-has been effectively refuted. Here we analyse chronometric data from 42 North American and Beringian archaeological sites using a Bayesian age modelling approach, and use the resulting chronological framework to elucidate spatiotemporal patterns of human dispersal. We then integrate these patterns with the available genetic and climatic evidence. The data obtained show that humans were probably present before, during and immediately after the Last Glacial Maximum (about 26.5-19 thousand years ago)(2,3)but that more widespread occupation began during a period of abrupt warming, Greenland Interstadial 1 (about 14.7-12.9 thousand years beforead 2000)(4). We also identify the near-synchronous commencement of Beringian, Clovis and Western Stemmed cultural traditions, and an overlap of each with the last dates for the appearance of 18 now-extinct faunal genera. Our analysis suggests that the widespread expansion of humans through North America was a key factor in the extinction of large terrestrial mammals.


A Bayesian age model suggests that human dispersal to the Americas probably began before the Last Glacial Maximum, overlapping with the last dates of appearance for several faunal genera.


  
Ice retreat in Wilkes Basin of East Antarctica during a warm interglacial 期刊论文
NATURE, 2020, 583 (7817) : 554-+
作者:  T. Blackburn;  G. H. Edwards;  S. Tulaczyk;  M. Scudder;  G. Piccione;  B. Hallet;  N. McLean;  J. C. Zachos;  B. Cheney;  J. T. Babbe
收藏  |  浏览/下载:18/0  |  提交时间:2020/08/09

Uranium isotopes in subglacial precipitates from the Wilkes Basin of the East Antarctic Ice Sheet reveal ice retreat during a warm Pleistocene interglacial period about 400,000 years ago.


Efforts to improve sea level forecasting on a warming planet have focused on determining the temperature, sea level and extent of polar ice sheets during Earth'  s past interglacial warm periods(1-3). About 400,000 years ago, during the interglacial period known as Marine Isotopic Stage 11 (MIS11), the global temperature was 1 to 2 degrees Celsius greater(2)and sea level was 6 to 13 metres higher(1,3). Sea level estimates in excess of about 10 metres, however, have been discounted because these require a contribution from the East Antarctic Ice Sheet(3), which has been argued to have remained stable for millions of years before and includes MIS11(4,5). Here we show how the evolution of(234)U enrichment within the subglacial waters of East Antarctica recorded the ice sheet'  s response to MIS11 warming. Within the Wilkes Basin, subglacial chemical precipitates of opal and calcite record accumulation of(234)U (the product of rock-water contact within an isolated subglacial reservoir) up to 20 times higher than that found in marine waters. The timescales of(234)U enrichment place the inception of this reservoir at MIS11. Informed by the(234)U cycling observed in the Laurentide Ice Sheet, where(234)U accumulated during periods of ice stability(6)and was flushed to global oceans in response to deglaciation(7), we interpret our East Antarctic dataset to represent ice loss within the Wilkes Basin at MIS11. The(234)U accumulation within the Wilkes Basin is also observed in the McMurdo Dry Valleys brines(8-10), indicating(11)that the brine originated beneath the adjacent East Antarctic Ice Sheet. The marine origin of brine salts(10)and bacteria(12)implies that MIS11 ice loss was coupled with marine flooding. Collectively, these data indicate that during one of the warmest Pleistocene interglacials, the ice sheet margin at the Wilkes Basin retreated to near the precipitate location, about 700 kilometres inland from the current position of the ice margin, which-assuming current ice volumes-would have contributed about 3 to 4 metres(13)to global sea levels.


  
Carbon loss from northern circumpolar permafrost soils amplified by rhizosphere priming 期刊论文
NATURE GEOSCIENCE, 2020
作者:  Keuper, Frida;  Wild, Birgit;  Kummu, Matti;  Beer, Christian;  Blume-Werry, Gesche;  Fontaine, Sebastien;  Gavazov, Konstantin;  Gentsch, Norman;  Guggenberger, Georg;  Hugelius, Gustaf;  Jalava, Mika;  Koven, Charles;  Krab, Eveline J.;  Kuhry, Peter;  Monteux, Sylvain;  Richter, Andreas;  Shahzad, Tanvir;  Weedon, James T.;  Dorrepaal, Ellen
收藏  |  浏览/下载:12/0  |  提交时间:2020/08/09
Breaking Earth's shell into a global plate network 期刊论文
NATURE COMMUNICATIONS, 2020, 11 (1)
作者:  Tang, C. A.;  Webb, A. A. G.;  Moore, W. B.;  Wang, Y. Y.;  Ma, T. H.;  Chen, T. T.
收藏  |  浏览/下载:10/0  |  提交时间:2020/07/21
Black Carbon and Precipitation: An Energetics Perspective 期刊论文
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 2020, 125 (13)
作者:  Sand, M.;  Samset, B. H.;  Tsigaridis, K.;  Bauer, S. E.;  Myhre, G.
收藏  |  浏览/下载:14/0  |  提交时间:2020/08/18
black carbon aerosols  rapid adjustments  precipitation  energy budget  
Temperature Inversion and Clouds Over the Arctic Ocean Observed by the 5th Chinese National Arctic Research Expedition 期刊论文
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 2020, 125 (13)
作者:  Wang, Ding;  Guo, Jianping;  Chen, Aijun;  Bian, Lingen;  Ding, Minghu;  Liu, Lin;  Lv, Yanmin;  Li, Jian;  Guo, Xiaoran;  Han, Yi
收藏  |  浏览/下载:14/0  |  提交时间:2020/08/18
cloud  temperature inversion  radiosonde  Arctic  
Multimodel Future Projections of the Regional Vegetation-Climate System Over East Asia: Comparison Between Two Ensemble Approaches 期刊论文
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 2020, 125 (13)
作者:  Liu, Weiguang;  Wang, Guiling;  Yu, Miao;  Chen, Haishan;  Jiang, Yelin
收藏  |  浏览/下载:12/0  |  提交时间:2020/08/18
climate change  East Asia  multimodel ensemble  vegetation-climate interactions  
Attribution of Evapotranspiration Changes in Humid Regions of China from 1982 to 2016 期刊论文
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 2020, 125 (13)
作者:  Zhang, Dan;  Liu, Xiaomang;  Zhang, Lu;  Zhang, Qi;  Gan, Rong;  Li, Xianghu
收藏  |  浏览/下载:9/0  |  提交时间:2020/08/18
attribution  evapotranspiration  climate variation  vegetation greening  
Climate From the McMurdo Dry Valleys, Antarctica, 1986-2017: Surface Air Temperature Trends and Redefined Summer Season 期刊论文
JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 2020, 125 (13)
作者:  Obryk, M. K.;  Doran, P. T.;  Fountain, A. G.;  Myers, M.;  McKay, C. P.
收藏  |  浏览/下载:6/0  |  提交时间:2020/08/18
McMurdo Dry Valleys  weather observations  summer season  
Substrate regulation leads to differential responses of microbial ammonia-oxidizing communities to ocean warming 期刊论文
NATURE COMMUNICATIONS, 2020, 11 (1)
作者:  Zheng, Zhen-Zhen;  Zheng, Li-Wei;  Xu, Min Nina;  Tan, Ehui;  Hutchins, David A.;  Deng, Wenchao;  Zhang, Yao;  Shi, Dalin;  Dai, Minhan;  Kao, Shuh-Ji
收藏  |  浏览/下载:11/0  |  提交时间:2020/07/21