DOI: 10.5194/cp-11-1197-2015
Scopus记录号: 2-s2.0-84942609661
论文题名: Early-Holocene warming in Beringia and its mediation by sea-level and vegetation changes
作者: Bartlein P.J. ; Edwards M.E. ; Hostetler S.W. ; Shafer S.L. ; Anderson P.M. ; Brubaker L.B. ; Lozhkin A.V.
刊名: Climate of the Past
ISSN: 18149324
出版年: 2015
卷: 11, 期: 9 起始页码: 1197
结束页码: 1222
语种: 英语
Scopus关键词: boundary condition
; climate modeling
; climate variation
; deciduous forest
; feedback mechanism
; general circulation model
; global warming
; growing season
; Holocene
; ice cover
; Northern Hemisphere
; paleoecology
; permafrost
; sea level change
; vegetation structure
; Alaska
; Canada
; Siberia
; United States
英文摘要: Arctic land-cover changes induced by recent global climate change (e.g., expansion of woody vegetation into tundra and effects of permafrost degradation) are expected to generate further feedbacks to the climate system. Past changes can be used to assess our understanding of feedback mechanisms through a combination of process modeling and paleo-observations. The subcontinental region of Beringia (northeastern Siberia, Alaska, and northwestern Canada) was largely ice-free at the peak of deglacial warming and experienced both major vegetation change and loss of permafrost when many arctic regions were still ice covered. The evolution of Beringian climate at this time was largely driven by global features, such as the amplified seasonal cycle of Northern Hemisphere insolation and changes in global ice volume and atmospheric composition, but changes in regional land-surface controls, such as the widespread development of thaw lakes, the replacement of tundra by deciduous forest or woodland, and the flooding of the Bering-Chukchi land bridge, were probably also important. We examined the sensitivity of Beringia's early Holocene climate to these regional-scale controls using a regional climate model (RegCM). Lateral and oceanic boundary conditions were provided by global climate simulations conducted using the GENESIS V2.01 atmospheric general circulation model (AGCM) with a mixed-layer ocean. We carried out two present-day simulations of regional climate - one with modern and one with 11 ka geography - plus another simulation for 6 ka. In addition, we performed five ∼ 11 ka climate simulations, each driven by the same global AGCM boundary conditions: (i) 11 ka Control , which represents conditions just prior to the major transitions (exposed land bridge, no thaw lakes or wetlands, widespread tundra vegetation), (ii) sea-level rise, which employed present-day continental outlines, (iii) vegetation change, with deciduous needleleaf and deciduous broadleaf boreal vegetation types distributed as suggested by the paleoecological record, (iv) thaw lakes, which used the present-day distribution of lakes and wetlands, and (v) post-11 ka All , incorporating all boundary conditions changed in experiments (ii)-(iv). We find that regional-scale controls strongly mediate the climate responses to changes in the large-scale controls, amplifying them in some cases, damping them in others, and, overall, generating considerable spatial heterogeneity in the simulated climate changes. The change from tundra to deciduous woodland produces additional widespread warming in spring and early summer over that induced by the 11 ka insolation regime alone, and lakes and wetlands produce modest and localized cooling in summer and warming in winter. The greatest effect is the flooding of the land bridge and shelves, which produces generally cooler conditions in summer but warmer conditions in winter and is most clearly manifest on the flooded shelves and in eastern Beringia. By 6 ka continued amplification of the seasonal cycle of insolation and loss of the Laurentide ice sheet produce temperatures similar to or higher than those at 11 ka, plus a longer growing season. © Author(s) 2015. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/49115
Appears in Collections: 气候变化与战略
There are no files associated with this item.
Recommended Citation:
Bartlein P.J.,Edwards M.E.,Hostetler S.W.,et al. Early-Holocene warming in Beringia and its mediation by sea-level and vegetation changes[J]. Climate of the Past,2015-01-01,11(9)