scholarly journals Last Glacial climate reconstruction by exploring glacier sensitivity to climate on the southeastern slope of the western Nyaiqentanglha Shan, Tibetan Plateau

2017 ◽  
Vol 63 (238) ◽  
pp. 361-371 ◽  
Author(s):  
XIANGKE XU ◽  
BAOLIN PAN ◽  
GUOCHENG DONG ◽  
CHAOLU YI ◽  
NEIL F. GLASSER
Keyword(s):  
Tibetan Plateau ◽  
Regional Climate ◽  
The Tibetan Plateau ◽  
Glacial Cycle ◽  
Geological Evidence ◽  
Oxygen Isotope Stage ◽  
Last Glacial ◽  
Mountain Glaciers ◽  
The Last Glacial Maximum ◽  
The Last Glacial

ABSTRACTImprovements in understanding glacial extents and chronologies for the southeastern slope of the western Nyaiqentanglha Shan on the Tibetan Plateau are required to understand regional climate changes during the Last Glacial cycle. A two-dimensional numerical model of mass balance, based on snow–ice melting factors, and of ice flow for mountain glaciers is used to assess the glacier sensitivity to climatic change in a catchment of the region. The model can reproduce valley glaciers, wide-tongued glaciers and a coalescing glacier within step temperature lowering and precipitation increasing experiments. The model sensitivity experiments also indicate that the dependence of glacier growth on temperature and/or precipitation is nonlinear. The model results suggest that the valley glaciers respond more sensitively to an imposed climate change than wide-tongued and coalescing glaciers. Guided by field geological evidence of former glacier extent and other independent paleoclimate reconstructions, the model is also used to constrain the most realistic multi-year mean temperatures to be 2.9–4.6°C and 1.8–2.5°C lower than present in the glacial stages of the Last Glacial Maximum and middle marine oxygen isotope stage 3, respectively.

scholarly journals Comparison of Cenozoic surface uplift and glacial-interglacial cycles on Himalaya-Tibet paleo-climate: Insights from a regional climate model

2017 ◽  
Author(s):  
Heiko Paeth ◽  
Christian Steger ◽  
Jingmin Li ◽  
Sebastian G. Mutz ◽  
Todd A. Ehlers
Keyword(s):  
Tibetan Plateau ◽  
Regional Climate Model ◽  
Central Asia ◽  
Last Glacial Maximum ◽  
Climate Model ◽  
Regional Climate ◽  
The Tibetan Plateau ◽  
Climate Anomalies ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract. Assessing paleo-climatic changes across the Tibetan Plateau and the underlying driving mechanisms provides insights for the natural variability in the Earth's climate system in response to tectonic processes and global climate change. In this study, we use a high-resolution regional climate model to investigate various episodes of distinct climate states over the Tibetan Plateau region during the Cenozoic rise of the Plateau and Quaternary glacial/interglacial cycles. The main objective is to compare climate changes during the Miocene-Pliocene uplift period with climate anomalies during the last glacial maximum and the mid-Holocene optimum, based on a consistent modeling framework. Reduced plateau elevation leads to regionally differentiated patterns of higher temperature and lower precipitation amount on the plateau itself, whereas surrounding regions are subject to colder conditions. In particular, Central Asia receives much more precipitation prior to the uplift, mainly due to a shift of the stationary wave train over Eurasia. Cluster analysis indicates that the continental-desert type climate, which is widespread over Central Asia today, appears with the Tibetan Plateau reaching 50 % of its present-day elevation. The mid-Holocene is characterized by slightly colder temperatures, and the last glacial maximum by considerably colder conditions over most of central and southern Asia. Precipitation anomalies during these episodes are less pronounced and spatially heterogeneous over the Tibetan Plateau. The simulated changes are in good agreement with available paleo-climatic reconstructions from proxy data. The present-day climate classification is only slightly sensitive to the changed boundary conditions in the Quaternary Quaternary. It is shown that in some regions of the Tibetan Plateau the climate anomalies during the Quaternary Quaternary have been as strong as the changes occurring during the uplift period.

scholarly journals Tree endurance on the Tibetan Plateau marks the world’s highest known tree line of the Last Glacial Maximum

2009 ◽  
Vol 185 (1) ◽  
pp. 332-342 ◽  
Author(s):  
Lars Opgenoorth ◽  
Giovanni G. Vendramin ◽  
Kangshan Mao ◽  
Georg Miehe ◽  
Sabine Miehe ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
The Tibetan Plateau ◽  
Tree Line ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial

scholarly journals Fennoscandian palaeoglaciology reconstructed using a glacial geological inversion model

1997 ◽  
Vol 43 (144) ◽  
pp. 283-299 ◽  
Author(s):  
Johan Kleman ◽  
Clas Hättestrand ◽  
Ingmar Borgström ◽  
Arjen Stroeven
Keyword(s):  
Flow Pattern ◽  
Numerical Models ◽  
Ice Sheet ◽  
Mountain Range ◽  
Glacial Cycle ◽  
Geological Evidence ◽  
Inversion Model ◽  
Last Glacial ◽  
Late Weichselian ◽  
The Last Glacial

AbstractThe evolution of ice-sheet configuration and flow pattern in Fennoscandia through the last glacial cycle was reconstructed using a glacial geological inversion model, i.e. a theoretical model that formalises the procedure of using the landform record to reconstruct ice sheets. The model uses mapped flow traces and deglacial melt-water landforms, as well as relative chronologies derived from cross-cutting striae and till lineations, as input data. Flow-trace systems were classified into four types: (i) time-transgressive wet-bed deglacial fans, (ii) time-transgressive frozen-bed deglacial fans, (iii) surge fans, and (iv) synchronous non-deglacial (event) fans. Using relative chronologies and aggregation of fans into glaciologically plausible patterns, a series of ice-sheet Configurations at different time slices was erected. A chronology was constructed through correlation with dated stratigraphical records and proxy data reflecting global ice volume. Geological evidence exists for several discrete ice-sheet configurations centred over the Scandinavian mountain range during the early Weichselian. The build-up of the main Weichselian Fennoscandian ice sheet started at approximately 70 Ka, and our results indicate that it was characterised by an ice sheet with a centre of mass located over southern Norway. This configuration had a flow pattern which is poorly reproduced by current numerical models of the Fennoscandian ice sheet. At the Last Glacial Maximum the main ice divide was located overthe Gulf of Bothnia. A major bend in the ice divide was caused by outflow of ice to the northwest over the lowest part of the Scandinavian mountain chain. Widespread areas of preserved pre-late-Weichselian landscapes indicate that the ice sheet had a frozen-bed core area, which was only partly diminished in size by inward-transgressive wet-bed zones during the decay phase.

scholarly journals Evolution of the large-scale atmospheric circulation in response to changing ice sheets over the last glacial cycle

2014 ◽  
Vol 10 (4) ◽  
pp. 1453-1471 ◽  
Author(s):  
M. Löfverström ◽  
R. Caballero ◽  
J. Nilsson ◽  
J. Kleman
Keyword(s):  
Atmospheric Circulation ◽  
Large Scale ◽  
Ice Sheets ◽  
Ice Sheet ◽  
Laurentide Ice Sheet ◽  
Glacial Cycle ◽  
Mean Flow ◽  
Geological Evidence ◽  
Last Glacial ◽  
The Last Glacial

Abstract. We present modelling results of the atmospheric circulation at the cold periods of marine isotope stage 5b (MIS 5b), MIS 4 and the Last Glacial Maximum (LGM), as well as the interglacial. The palaeosimulations are forced by ice-sheet reconstructions consistent with geological evidence and by appropriate insolation and greenhouse gas concentrations. The results suggest that the large-scale atmospheric winter circulation remained largely similar to the interglacial for a significant part of the glacial cycle. The proposed explanation is that the ice sheets were located in areas where their interaction with the mean flow is limited. However, the LGM Laurentide Ice Sheet induces a much larger planetary wave that leads to a zonalisation of the Atlantic jet. In summer, the ice-sheet topography dynamically induces warm temperatures in Alaska and central Asia that inhibits the expansion of the ice sheets into these regions. The warm temperatures may also serve as an explanation for westward propagation of the Eurasian Ice Sheet from MIS 4 to the LGM.

scholarly journals The deglaciation of coastal areas of southeast Greenland

The Holocene ◽  
2018 ◽  
Vol 28 (9) ◽  
pp. 1535-1544 ◽  
Author(s):  
Laurence M Dyke ◽  
Anna LC Hughes ◽  
Camilla S Andresen ◽  
Tavi Murray ◽  
John F Hiemstra ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Younger Dryas ◽  
Greenland Ice Sheet ◽  
Coastal Areas ◽  
Glacial Cycle ◽  
Last Glacial ◽  
The North ◽  
Exposure Ages ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Large marine-terminating glaciers around the margins of the Greenland Ice Sheet have retreated, accelerated and thinned over the last two decades. Relatively little is known about the longer term behaviour of the Greenland Ice Sheet, yet this information is valuable for assessing the significance of modern changes. We address this by reporting 11 new beryllium-10 (10Be) exposure ages from previously uninvestigated coastal areas across southeast Greenland. The new ages are combined with existing data from the region to assess the timing of glacier retreat after the Last Glacial Maximum. The results show that deglaciation occurred first in the north of the region (~68°N) and progressed southwards. This north–south progression is attributed to the influence of the warm Irminger Current on the ice margin. Areas in the south of the region were isolated from the warm waters by the shallow bathymetry of the continental shelf. This demonstrates that oceanographic forcing paced the deglaciation of southeast Greenland through the Younger Dryas and early Holocene. In most areas of southeast Greenland bedrock ages are systematically older than their counterpart boulder samples; this offset is likely the result of inherited 10Be content in bedrock surfaces. This suggests that subglacial erosion during the last glacial cycle was insufficient to completely remove pre-existing 10Be content. Alternatively, this pattern may be the signature of a substantial retreat and advance cycle prior to final Holocene deglaciation.

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