DOI: 10.1016/j.quascirev.2016.10.023
Scopus记录号: 2-s2.0-84996844076
论文题名: Episodic Neoglacial snowline descent and glacier expansion on Svalbard reconstructed from the 14C ages of ice-entombed plants
作者: Miller G.H. ; Landvik J.Y. ; Lehman S.J. ; Southon J.R.
刊名: Quaternary Science Reviews
ISSN: 2773791
出版年: 2017
卷: 155 起始页码: 67
结束页码: 78
语种: 英语
英文关键词: Climate
; Glacier
; Holocene
; Little Ice Age
; Medieval
; Neoglaciation
; Radiocarbon
; Recent warming
; Svalbard
Scopus关键词: Aggregates
; Atmospheric radiation
; Expansion
; Glacial geology
; Glaciers
; Incident solar radiation
; Solar radiation
; Vegetation
; Climate
; Holocenes
; Little Ice Age
; Medieval
; Neoglaciation
; Radiocarbon
; Recent warming
; Svalbard
; Ice
英文摘要: The response of the Northern Hemisphere cryosphere to the monotonic decline in summer insolation and variable radiative forcing during the Holocene has been one of irregular expansion culminating in the Little Ice Age, when most glaciers attained their maximum late Holocene dimensions. Although periods of intervening still-stand or ice-retreat can be reconstructed by direct dating of ice-recessional features, defining times of Neoglacial ice growth has been limited to indirect proxies preserved in distal archives. Here we report 45 precise radiocarbon dates on in situ plants emerging from beneath receding glaciers on Svalbard that directly date the onset of snowline descent and glacier expansion, entombing the plants. Persistent snowline lowering occurred between 4.0 and 3.4 ka, but with little additional persistent lowering until early in the first millennium AD. Populations of individual 14C calendar age results and their aggregate calendar age probabilities define discrete episodes of vegetation kill and snowline lowering 240–340 AD, 410–540 AD and 670–750 AD, each with a lower snowline than the preceding episode, followed by additional snowline lowering between 1000 and 1220 AD, and between 1300 and 1450 AD. Snowline changes after 1450 AD, including the maximum ice extent of the Little Ice Age are not resolved by our collections, although snowlines remained lower than their 1450 AD level until the onset of modern warming. A time-distance diagram derived from a 250-m-long transect of dated ice-killed plants documents ice-margin advances ∼750, ∼1100 and after ∼1500 AD, concordant with distributed vegetation kill ages seen in the aggregate data set, supporting our central thesis that vegetation kill ages provide direct evidence of snowline lowering and cryospheric expansion. The mid- to late-Holocene history of snowline lowering on Svalbard is similar to ELA reconstructions of Norwegian and Svalbard cirque glaciers, and consistent with a cryospheric response to the secular decline of regional summertime insolation and stepped changes in nearby surface ocean environments. The widespread exposure of entombed plants dating from the first millennium AD suggests that Svalbard's average summer temperatures of the past century now exceed those of any century since at least 700 AD, including medieval times. © 2016 Elsevier Ltd Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/59361
Appears in Collections: 过去全球变化的重建
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作者单位: Institute of Arctic and Alpine Research, University of Colorado Boulder, United States; Dept. Geological Sciences, University of Colorado Boulder, United States; Dept. Environment & Agriculture, Curtin University, Perth, WA, Australia; Dept. Environmental Sciences, Norwegian University of Life Sciences, Box 5003, Aas, Norway; Earth System Science Dept., University of California Irvine, United States
Recommended Citation:
Miller G.H.,Landvik J.Y.,Lehman S.J.,et al. Episodic Neoglacial snowline descent and glacier expansion on Svalbard reconstructed from the 14C ages of ice-entombed plants[J]. Quaternary Science Reviews,2017-01-01,155