scholarly journals Spatial pattern of accumulation at Taylor Dome during the last glacial inception: stratigraphic constraints from Taylor Glacier

2018 ◽  
Author(s):  
James A. Menking ◽  
Edward J. Brook ◽  
Sarah A. Shackleton ◽  
Jeffrey P. Severinghaus ◽  
Michael Dyonisius ◽  
...  
Keyword(s):  
Ice Core ◽  
Snow Accumulation ◽  
Ice Age ◽  
Spatial Gradient ◽  
Age Difference ◽  
Last Glacial ◽  
Accumulation Zone ◽  
Glacier Ice ◽  
Taylor Glacier ◽  
The Last Glacial

Abstract. A new ice core retrieved from the Taylor Glacier blue ice area contains ice and air spanning the Marine Isotope Stage (MIS) 5/4 transition (74 to 65 ka), a period of global cooling and glacial inception. Dating the ice and air bubbles in the new ice core reveals an ice age-gas age difference (Δage) approaching 10 ka during MIS 4, implying very low accumulation at the Taylor Glacier accumulation zone on the northern flank of Taylor Dome. A revised chronology for the Taylor Dome ice core (80 to 55 ka), situated to the south of the Taylor Glacier accumulation zone, shows that Δage did not exceed 2.5 ka at that location. The difference in Δage between the new Taylor Glacier ice core and the Taylor Dome ice core implies a spatial gradient in snow accumulation across Taylor Dome that intensified during the last glacial inception and through MIS 4.

scholarly journals Spatial pattern of accumulation at Taylor Dome during Marine Isotope Stage 4: stratigraphic constraints from Taylor Glacier

2019 ◽  
Vol 15 (4) ◽  
pp. 1537-1556 ◽  
Author(s):  
James A. Menking ◽  
Edward J. Brook ◽  
Sarah A. Shackleton ◽  
Jeffrey P. Severinghaus ◽  
Michael N. Dyonisius ◽  
...  
Keyword(s):  
Last Glacial Maximum ◽  
Ice Core ◽  
Ice Cores ◽  
Snow Accumulation ◽  
Marine Isotope Stage ◽  
Last Glacial ◽  
Accumulation Zone ◽  
Taylor Glacier ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract. New ice cores retrieved from the Taylor Glacier (Antarctica) blue ice area contain ice and air spanning the Marine Isotope Stage (MIS) 5–4 transition, a period of global cooling and ice sheet expansion. We determine chronologies for the ice and air bubbles in the new ice cores by visually matching variations in gas- and ice-phase tracers to preexisting ice core records. The chronologies reveal an ice age–gas age difference (Δage) approaching 10 ka during MIS 4, implying very low snow accumulation in the Taylor Glacier accumulation zone. A revised chronology for the analogous section of the Taylor Dome ice core (84 to 55 ka), located to the south of the Taylor Glacier accumulation zone, shows that Δage did not exceed 3 ka. The difference in Δage between the two records during MIS 4 is similar in magnitude but opposite in direction to what is observed at the Last Glacial Maximum. This relationship implies that a spatial gradient in snow accumulation existed across the Taylor Dome region during MIS 4 that was oriented in the opposite direction of the accumulation gradient during the Last Glacial Maximum.

scholarly journals Vostok, Antarctica, Ice Core: The Dust Record Over The Last Climatic Cycle (∼160 ka) (Abstract)

1988 ◽  
Vol 11 ◽  
pp. 204-204
Author(s):  
L. Mounier ◽  
J. R. Petit ◽  
J. Jouzel ◽  
C. Lorius ◽  
Ye. S. Korotkevich ◽  
...  
Keyword(s):  
Total Concentration ◽  
Ice Core ◽  
Ice Cores ◽  
Optical Microscope ◽  
Ice Age ◽  
Maximum Temperature ◽  
Temperature Changes ◽  
Last Glacial ◽  
Chemical Measurements ◽  
The Last Glacial

The 2083 m Vostok Antarctic ice core provides a unique opportunity for access to many paleoclimatic and paleo-environmental proxy data. This core, which has been dated by using a glaciological model, fully covers the last glacial-interglacial cycle, and goes back to the ice age which preceded the last interglaciai (−160 ka B P ).A continuous deuterium record is now available and we have interpreted it in terms of local temperature changes. This record is dominated by the large 100 ka glacial-inter-glacial oscillation, with a maximum temperature amplitude of about 11°C; the long Last Glacial period is very well documented and it is confirmed that the warmest part of the Last Interglaciai period was about 2°C warmer than the Holocene. Comparison with the ice-volume marine record shows that the Vostok climate record is of relatively large geographical significance, which makes it possible to establish, over the last 160 ka, the link between worldwide climatic changes and the Vostok dust record that we present here.This dust content corresponds to the non-soluble microparticles. It was obtained on a discontinuous basis (1 sample = about ∼10 m). Due to the very low concentration of some samples (down to 20 x 10−9gg−1) and cracks in the ice from the first 1000 m depth, we used stringent decontamination procedures. Size distribution and total concentration were measured, using a Coulter counter and an optical microscope; the results were tested against chemical measurements (aluminium concentration). In previous studies, it has been shown that the main proportion of insoluble microparticles is of terrigenous origin and represents the small-sized (radius <2 μm) dust produced on the continents.The Vostok record displays an increase in dust concentration of up to 20 times during the coldest climatic periods, coupled with the presence of larger particles. It confirms, on a much longer time-scale, a characteristic previously noted in Antarctic and Greenland ice cores over the Last Glacial Maximum. This large increase is attributed to a greater areal extent of global tropical aridity during the cold periods, coupled with higher efficiency of atmospheric circulation in respect of dust production and transport. Beyond this, the relationship between the dust input and the successive stages during the Last Glacial is now very well documented and will be discussed with a view to correlating the Vostok climatic record with other marine and terrestrial paleodata.

scholarly journals Model evolution of the middle atmospheric palaeoenvironments

MAUSAM ◽  
2021 ◽  
Vol 52 (1) ◽  
pp. 297-306
Author(s):  
GUFRAN BEIG
Keyword(s):  
Vertical Distribution ◽  
Thermal Structure ◽  
Ice Core ◽  
Ice Age ◽  
Ozone Content ◽  
Glacial Period ◽  
Last Glacial Period ◽  
Last Glacial ◽  
Last Ice Age ◽  
The Last Glacial

Ice core air analysis has indicated a significant variation in the atmospheric contents of the greenhouse gases CO2, CH4 and N2O from the last ice age to the present period. This may have contributed in altering the vertical distribution of temperature and composition of the atmosphere about which not much information is available. The two dimensional interactive model of radiation, dynamics and chemistry has been used to reconstruct the annual vertical distribution of thermal structure and trace gas concentrations of the middle atmosphere for the periods extending from last ice age to the present. For this purpose, ice core air data of the above mentioned forcing parameters are used as input to the model for different time frames including Mounder Maximum, Roman maximum, pre-industrial period and the last glacial period. Model results show that the considerable reduction in the greenhouse gas content for the last ice age has resulted in colling of troposphere and a warming by about 10 to 15° K in the upper stratosphere as compared to present. The variation in temperature is closely related with the water vapour content. The percentage change in ozone concentration for the last glacial period is to a miximum of 50% near the poles in the upper stratosphere and about 10% in the tropics. A significant decrease in the hydroxyl content in the last ice age must have contributed in increasing the ozone content above 30 km. however, the total integrated ozone content appears to show marginal variations from last ice age to the present due to several counter-balancing effects.

scholarly journals Atmospheric gas records from Taylor Glacier, Antarctica, reveal ancient ice with ages spanning the entire last glacial cycle

2017 ◽  
Vol 13 (7) ◽  
pp. 943-958 ◽  
Author(s):  
Daniel Baggenstos ◽  
Thomas K. Bauska ◽  
Jeffrey P. Severinghaus ◽  
James E. Lee ◽  
Hinrich Schaefer ◽  
...  
Keyword(s):  
Large Scale ◽  
Ice Core ◽  
Ice Sheet ◽  
Last Deglaciation ◽  
Glacial Cycle ◽  
Last Glacial ◽  
Climate Reconstructions ◽  
Age Model ◽  
Taylor Glacier ◽  
The Last Glacial

Abstract. Old ice for paleo-environmental studies, traditionally accessed through deep core drilling on domes and ridges on the large ice sheets, can also be retrieved at the surface from ice sheet margins and blue ice areas. The practically unlimited amount of ice available at these sites satisfies a need in the community for studies of trace components requiring large sample volumes. For margin sites to be useful as ancient ice archives, the ice stratigraphy needs to be understood and age models need to be established. We present measurements of trapped gases in ice from Taylor Glacier, Antarctica, to date the ice and assess the completeness of the stratigraphic section. Using δ18O of O2 and methane concentrations, we unambiguously identify ice from the last glacial cycle, covering every climate interval from the early Holocene to the penultimate interglacial. A high-resolution transect reveals the last deglaciation and the Last Glacial Maximum (LGM) in detail. We observe large-scale deformation in the form of folding, but individual stratigraphic layers do not appear to have undergone irregular thinning. Rather, it appears that the entire LGM–deglaciation sequence has been transported from the interior of the ice sheet to the surface of Taylor Glacier relatively undisturbed. We present an age model that builds the foundation for gas studies on Taylor Glacier. A comparison with the Taylor Dome ice core confirms that the section we studied on Taylor Glacier is better suited for paleo-climate reconstructions of the LGM due to higher accumulation rates.

scholarly journals An improved and continuous synchronization of the Greenland ice-core and Hulu Cave U-Th timescales using probabilistic inversion

2021 ◽  
Author(s):  
Francesco Muschitiello
Keyword(s):  
Transfer Functions ◽  
Ice Core ◽  
Greenland Ice Sheet ◽  
Ice Cores ◽  
Age Difference ◽  
Last Glacial ◽  
Annual Layer ◽  
Counting Error ◽  
Matching Techniques ◽  
The Last Glacial

Abstract. This study presents the first continuously measured transfer functions that quantify the age difference between the Greenland Ice-Core Chronology 2005 (GICC05) and the Hulu Cave U-Th timescale during the last glacial period. The transfer functions were estimated using an automated algorithm for Bayesian inversion that allows inferring a continuous and objective synchronization between Greenland ice-core and Hulu Cave proxy signals. The algorithm explicitly considers prior knowledge on the maximum counting error (MCE) of GICC05, but also samples synchronization scenarios that exceed the differential dating uncertainty of the annual-layer count in ice cores, which are currently not detectable using conventional tie-point alignments or wiggle-matching techniques. The consistency and accuracy of the results were ensured by estimating two independent synchronizations: a climate synchronization based on climate proxy records, and a climate-independent synchronization based on cosmogenic radionuclide data (i.e. 10Be and 14C). The transfer functions are up to 40 % more precise than previous estimates and significantly reduce the absolute dating uncertainty of the GICC05 back to 48 kyr ago. The results highlight that the annual-layer counting error of GICC05 is not strictly correlated over extended periods of time, and that within certain Greenland Stadials the differential dating uncertainty is likely underestimated by 7.5–20 %. Importantly, the analysis implies for the first time that during the Last Glacial Maximum GICC05 overcounts ice layers by 15–25 % –a bias attributable to a higher frequency of sub-annual layers due to changes in the seasonal cycle of precipitation and mode of dust deposition to the Greenland Ice Sheet. The new timescale transfer functions provide important constraints on the uncertainty surrounding the stratigraphic dating of the Greenland age-scale and enable an improved chronological integration of ice cores, U-Th-dated and radiocarbon-dated paleoclimate records on a common timeline. The transfer functions are available as supplements to this study.

scholarly journals Vostok, Antarctica, Ice Core: The Dust Record Over The Last Climatic Cycle (∼160 ka) (Abstract)

1988 ◽  
Vol 11 ◽  
pp. 204
Author(s):  
L. Mounier ◽  
J. R. Petit ◽  
J. Jouzel ◽  
C. Lorius ◽  
Ye. S. Korotkevich ◽  
...  
Keyword(s):  
Total Concentration ◽  
Ice Core ◽  
Ice Cores ◽  
Optical Microscope ◽  
Ice Age ◽  
Maximum Temperature ◽  
Temperature Changes ◽  
Last Glacial ◽  
Chemical Measurements ◽  
The Last Glacial

The 2083 m Vostok Antarctic ice core provides a unique opportunity for access to many paleoclimatic and paleo-environmental proxy data. This core, which has been dated by using a glaciological model, fully covers the last glacial-interglacial cycle, and goes back to the ice age which preceded the last interglaciai (−160 ka B P ). A continuous deuterium record is now available and we have interpreted it in terms of local temperature changes. This record is dominated by the large 100 ka glacial-inter-glacial oscillation, with a maximum temperature amplitude of about 11°C; the long Last Glacial period is very well documented and it is confirmed that the warmest part of the Last Interglaciai period was about 2°C warmer than the Holocene. Comparison with the ice-volume marine record shows that the Vostok climate record is of relatively large geographical significance, which makes it possible to establish, over the last 160 ka, the link between worldwide climatic changes and the Vostok dust record that we present here. This dust content corresponds to the non-soluble microparticles. It was obtained on a discontinuous basis (1 sample = about ∼10 m). Due to the very low concentration of some samples (down to 20 x 10−9gg−1) and cracks in the ice from the first 1000 m depth, we used stringent decontamination procedures. Size distribution and total concentration were measured, using a Coulter counter and an optical microscope; the results were tested against chemical measurements (aluminium concentration). In previous studies, it has been shown that the main proportion of insoluble microparticles is of terrigenous origin and represents the small-sized (radius &lt;2 μm) dust produced on the continents. The Vostok record displays an increase in dust concentration of up to 20 times during the coldest climatic periods, coupled with the presence of larger particles. It confirms, on a much longer time-scale, a characteristic previously noted in Antarctic and Greenland ice cores over the Last Glacial Maximum. This large increase is attributed to a greater areal extent of global tropical aridity during the cold periods, coupled with higher efficiency of atmospheric circulation in respect of dust production and transport. Beyond this, the relationship between the dust input and the successive stages during the Last Glacial is now very well documented and will be discussed with a view to correlating the Vostok climatic record with other marine and terrestrial paleodata.

scholarly journals Atmospheric gas records from Taylor Glacier, Antarctica, reveal ancient ice with ages spanning the entire last glacial cycle

2017 ◽  
Author(s):  
Daniel Baggenstos ◽  
Thomas K. Bauska ◽  
Jeffrey P. Severinghaus ◽  
James E. Lee ◽  
Hinrich Schaefer ◽  
...  
Keyword(s):  
Large Scale ◽  
Ice Core ◽  
Ice Sheet ◽  
Last Deglaciation ◽  
Glacial Cycle ◽  
Last Glacial ◽  
Climate Reconstructions ◽  
Age Model ◽  
Taylor Glacier ◽  
The Last Glacial

Abstract. Old ice for paleo-environmental studies, traditionally accessed through deep core drilling on domes and ridges on the large ice sheets, can also be retrieved at the surface from ice sheet margins and blue ice areas. The practically unlimited amount of ice available at these sites satisfies a need in the community for studies of trace components requiring large sample volumes. For margin sites to be useful as ancient ice archives, the ice stratigraphy needs to be understood and age models need to be established. We present measurements of trapped gases in ice from Taylor Glacier, Antarctica, to date the ice and assess the completeness of the stratigraphic section. Using δ18O of O2 and methane concentrations, we unambiguously identify ice from the last glacial cycle, covering every climate interval from the early Holocene to the penultimate interglacial. A high-resolution transect reveals the last deglaciation and the Last Glacial Maximum (LGM) in detail. We observe large-scale deformation in the form of folding, but individual stratigraphic layers do not appear to have undergone irregular thinning. Rather, it appears that the entire LGM-deglaciation sequence has been transported from the interior of the ice sheet to the surface of Taylor Glacier relatively undisturbed. We present an age model that builds the foundation for gas studies on Taylor Glacier. A comparison with the Taylor Dome ice core confirms that the section we studied on Taylor Glacier is better suited for paleo-climate reconstructions of the LGM due to higher accumulation rates.

scholarly journals A new Greenland ice core chronology for the last glacial termination

2006 ◽  
Vol 111 (D6) ◽  
Author(s):  
S. O. Rasmussen ◽  
K. K. Andersen ◽  
A. M. Svensson ◽  
J. P. Steffensen ◽  
B. M. Vinther ◽  
...  
Keyword(s):  
Ice Core ◽  
Last Glacial ◽  
The Last Glacial ◽  
Glacial Termination

scholarly journals Glaciation and deglaciation mechanisms in a coupled two-dimensional climate—ice-sheet model

1993 ◽  
Vol 39 (131) ◽  
pp. 45-49 ◽  
Author(s):  
André Berger ◽  
Hubert Gallée ◽  
Christian Tricot
Keyword(s):  
Ice Core ◽  
Ice Sheets ◽  
Low Frequency ◽  
Two Dimensional ◽  
Atmospheric Concentration ◽  
Last Glacial ◽  
Simulated Climate ◽  
Milankovitch Theory ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract A two-dimensional model which links the atmosphere, the mixed layer of the ocean, the sea ice, the continents, the ice sheets and their underlying bedrock has been used to test the Milankovitch theory over the last glacial—interglacial cycle. It was found that the orbital variations alone can induce, in such a system, feed-backs sufficient to generate the low-frequency part of the climatic variations over the last 122 kyear. These simulated variations at the astronomical time-scale are broadly in agreement with ice volume and sea-level reconstructions independently obtained from geological data. Imperfections in the simulated climate were the insufficient southward extent of the ice sheets and the too small hemispheric cooling during the last glacial maximum. These deficiencies were partly remedied in a further experiment (Gallée and others, in press) by using the time-dependent CO2 atmospheric concentration given by the Vostok ice core in addition to the astronomical forcing. For this second experiment, the main mechanisms and feedbacks responsible for the glaciation and the deglaciation in the model are discussed here.

Sign in / Sign up

Export Citation Format

Share Document