Duration of Greenland Stadial 22 and ice-gas Δage from counting of annual layers in Greenland NGRIP ice core

Abstract. The NorthGRIP ice core chronology GICC05modelext is composed of the annual-layer counted GICC05 chronology to 60 kyr before 2000 AD (b2k), and an ice flow model dating the deepest part of the ice core to 123 kyr b2k. Determination of annual strata in ice beyond 60 kyr b2k has been challenged by the thinning of annual layers to <1 cm and the appearance of microfolds in some early glacial strata. We report high-resolution measurements of a 50 m section of the NorthGRIP ice core and corresponding annual layer thicknesses, constraining the duration of the Greenland Stadial (GS-22) between Greenland Interstadials (GIs) 21 and 22 which occurred between approximately 89 (end of GI-22) and 83 kyr b2k (onset of GI-21) depending on the chronology used. Multiple analytes (insoluble dust particles, electrolytic conductivity, ammonium and sodium) were determined in annual layers of ice often thinner than 1 cm. From annual layer counting, we find that GS-22 lasted 2894 ± 198 yr and was followed by a GI-21 pre-cursor event lasting 350 ± 19 yr. Our layer-based counting agrees with the duration of GS-22 determined from the NALPS speleothem record (3250 ± 526 yr) but not with that of the GICC05modelext chronology (2620 yr). These results show that GICC05modelext overestimates accumulation and/or underestimates thinning in this early part of the last glacial period. We also revise the NorthGRIP ice depth-gas depth (5.67 ± 0.18 m) and ice age-gas age (550 ± 52 yr) differences at the warming onset of GI-21, observing that δ15N increases before CH4 concentration by no more than a few decades.

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South Pole glacial climate reconstruction from multi-borehole laser particulate stratigraphy

Journal of Glaciology ◽

10.3189/2013jog13j068 ◽

2013 ◽

Vol 59 (218) ◽

pp. 1117-1128 ◽

Cited By ~ 14

Author(s):

Keyword(s):

Particle Physics ◽

Volcanic Ash ◽

Ice Core ◽

Hot Water ◽

Radiometric Dating ◽

South Pole ◽

Last Glacial Period ◽

Annual Layer ◽

Paleoclimate Records ◽

The Last Glacial

AbstractThe IceCube Neutrino Observatory and its prototype, AMANDA, were built in South Pole ice, using powerful hot-water drills to cleanly bore >100 holes to depths up to 2500 m. The construction of these particle physics detectors provided a unique opportunity to examine the deep ice sheet using a variety of novel techniques. We made high-resolution particulate profiles with a laser dust logger in eight of the boreholes during detector commissioning between 2004 and 2010. The South Pole laser logs are among the most clearly resolved measurements of Antarctic dust strata during the last glacial period and can be used to reconstruct paleoclimate records in exceptional detail. Here we use manual and algorithmic matching to synthesize our South Pole measurements with ice-core and logging data from Dome C, East Antarctica. We derive impurity concentration, precision chronology, annual-layer thickness, local spatial variability, and identify several widespread volcanic ash depositions useful for dating. We also examine the interval around ∼74 ka recently isolated with radiometric dating to bracket the Toba (Sumatra) supereruption.

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Duration of Greenland Stadial 22 and ice-gas Δage from counting of annual layers in Greenland NGRIP ice core

Climate of the Past ◽

10.5194/cp-8-1839-2012 ◽

2012 ◽

Vol 8 (6) ◽

pp. 1839-1847 ◽

Cited By ~ 20

Author(s):

P. Vallelonga ◽

G. Bertagna ◽

T. Blunier ◽

H. A. Kjær ◽

T. J. Popp ◽

...

Keyword(s):

High Resolution ◽

Ice Core ◽

Ice Age ◽

Age Difference ◽

Glacial Period ◽

Annual Layer ◽

Chemical Impurities ◽

Dronning Maud Land ◽

Ice Core Records

Abstract. High-resolution measurements of chemical impurities and methane concentrations in Greenland ice core samples from the early glacial period allow the extension of annual-layer counted chronologies and the improvement of gas age-ice age difference (Δage) essential to the synchronization of ice core records. We report high-resolution measurements of a 50 m section of the NorthGRIP ice core and corresponding annual layer thicknesses in order to constrain the duration of the Greenland Stadial 22 (GS-22) between Greenland Interstadials (GIs) 21 and 22, for which inconsistent durations and ages have been reported from Greenland and Antarctic ice core records as well as European speleothems. Depending on the chronology used, GS-22 occurred between approximately 89 (end of GI-22) and 83 kyr b2k (onset of GI-21). From annual layer counting, we find that GS-22 lasted between 2696 and 3092 years and was followed by a GI-21 pre-cursor event lasting between 331 and 369 yr. Our layer-based counting agrees with the duration of stadial 22 as determined from the NALPS speleothem record (3250 ± 526 yr) but not with that of the GICC05modelext chronology (2620 yr) or an alternative chronology based on gas-marker synchronization to EPICA Dronning Maud Land ice core. These results show that GICC05modelext overestimates accumulation and/or underestimates thinning in this early part of the last glacial period. We also revise the possible ranges of NorthGRIP Δdepth (5.49 to 5.85 m) and Δage (498 to 601 yr) at the warming onset of GI-21 as well as the Δage range at the onset of the GI-21 precursor warming (523 to 654 yr), observing that temperature (represented by the δ15N proxy) increases before CH4 concentration by no more than a few decades.

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Model evolution of the middle atmospheric palaeoenvironments

MAUSAM ◽

10.54302/mausam.v52i1.1696 ◽

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.

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A change in seasonality in Greenland during a Dansgaard–Oeschger warming

Annals of Glaciology ◽

10.3189/172756408784700590 ◽

2008 ◽

Vol 48 ◽

pp. 19-24 ◽

Cited By ~ 5

Author(s):

Elizabeth R. Thomas ◽

Robert Mulvaney ◽

Eric W. Wolff

Keyword(s):

Seasonal Cycle ◽

Ice Core ◽

Chemical Deposition ◽

Last Glacial Period ◽

Glacial Ice ◽

The North ◽

Annual Layer ◽

First Time ◽

Very High ◽

The Last Glacial

AbstractA new sub-seasonal chemical record is presented from the North Greenland Icecore Project (NorthGRIP) ice core during the onset of one of the longest and strongest interstadials of the last glacial period, Dansgaard–Oeschger event 8 (approximately 38 000 years ago). This is the first time that a record of such resolution has been achieved over several metres of deep glacial ice and provides a unique opportunity for using additional parameters to carry out accurate dating using annual-layer counting. The very high-resolution chemical data were used to assess the phasing of various ions and determine changes in the seasonal strength of chemical deposition and the shape of the seasonal cycle. The study shows that a change in seasonality accompanied the dramatic warming transition from stadial to interstadial conditions in Greenland.

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

Annals of Glaciology ◽

10.3189/s0260305500006625 ◽

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.

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New constraints on the gas age-ice age difference along the EPICA ice cores, 0–50 kyr

Climate of the Past ◽

10.5194/cp-3-527-2007 ◽

2007 ◽

Vol 3 (3) ◽

pp. 527-540 ◽

Cited By ~ 78

Author(s):

L. Loulergue ◽

F. Parrenin ◽

T. Blunier ◽

J.-M. Barnola ◽

R. Spahni ◽

...

Keyword(s):

Ice Core ◽

Phase Relationship ◽

Ice Cores ◽

Climatic Conditions ◽

Ice Age ◽

Age Difference ◽

Last Deglaciation ◽

Last Glacial Period ◽

Polar Ice Sheets ◽

Dronning Maud Land

Abstract. Gas is trapped in polar ice sheets at ~50–120 m below the surface and is therefore younger than the surrounding ice. Firn densification models are used to evaluate this ice age-gas age difference (Δage) in the past. However, such models need to be validated by data, in particular for periods colder than present day on the East Antarctic plateau. Here we bring new constraints to test a firn densification model applied to the EPICA Dome C (EDC) site for the last 50 kyr, by linking the EDC ice core to the EPICA Dronning Maud Land (EDML) ice core, both in the ice phase (using volcanic horizons) and in the gas phase (using rapid methane variations). We also use the structured 10Be peak, occurring 41 kyr before present (BP) and due to the low geomagnetic field associated with the Laschamp event, to experimentally estimate the Δage during this event. Our results seem to reveal an overestimate of the Δage by the firn densification model during the last glacial period at EDC. Tests with different accumulation rates and temperature scenarios do not entirely resolve this discrepancy. Although the exact reasons for the Δage overestimate at the two EPICA sites remain unknown at this stage, we conclude that current densification model simulations have deficits under glacial climatic conditions. Whatever the cause of the Δage overestimate, our finding suggests that the phase relationship between CO2 and EDC temperature previously inferred for the start of the last deglaciation (lag of CO2 by 800±600 yr) seems to be overestimated.

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Temperature and mineral dust variability recorded in two low-accumulation Alpine ice cores over the last millennium

Climate of the Past ◽

10.5194/cp-14-21-2018 ◽

2018 ◽

Vol 14 (1) ◽

pp. 21-37 ◽

Cited By ~ 13

Author(s):

Pascal Bohleber ◽

Tobias Erhardt ◽

Nicole Spaulding ◽

Helene Hoffmann ◽

Hubertus Fischer ◽

...

Keyword(s):

Time Series ◽

Mineral Dust ◽

Ice Core ◽

Ice Cores ◽

Temperature Reconstruction ◽

Relative Increase ◽

Ice Age ◽

European Alps ◽

Stable Water Isotopes ◽

Annual Layer

Abstract. Among ice core drilling sites in the European Alps, Colle Gnifetti (CG) is the only non-temperate glacier to offer climate records dating back at least 1000 years. This unique long-term archive is the result of an exceptionally low net accumulation driven by wind erosion and rapid annual layer thinning. However, the full exploitation of the CG time series has been hampered by considerable dating uncertainties and the seasonal summer bias in snow preservation. Using a new core drilled in 2013 we extend annual layer counting, for the first time at CG, over the last 1000 years and add additional constraints to the resulting age scale from radiocarbon dating. Based on this improved age scale, and using a multi-core approach with a neighbouring ice core, we explore the time series of stable water isotopes and the mineral dust proxies Ca2+ and insoluble particles. Also in our latest ice core we face the already known limitation to the quantitative use of the stable isotope variability based on a high and potentially non-stationary isotope/temperature sensitivity at CG. Decadal trends in Ca2+ reveal substantial agreement with instrumental temperature and are explored here as a potential site-specific supplement to the isotope-based temperature reconstruction. The observed coupling between temperature and Ca2+ trends likely results from snow preservation effects and the advection of dust-rich air masses coinciding with warm temperatures. We find that if calibrated against instrumental data, the Ca2+-based temperature reconstruction is in robust agreement with the latest proxy-based summer temperature reconstruction, including a “Little Ice Age” cold period as well as a medieval climate anomaly. Part of the medieval climate period around AD 1100–1200 clearly stands out through an increased occurrence of dust events, potentially resulting from a relative increase in meridional flow and/or dry conditions over the Mediterranean.

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Climatic Record From an Ice Margin Area in East Antarctica

Annals of Glaciology ◽

10.1017/s0260305500008843 ◽

1990 ◽

Vol 14 ◽

pp. 323-327 ◽

Cited By ~ 6

Author(s):

T.D. Yao ◽

J.R. Petit ◽

J. Jouzel ◽

C. Lorius ◽

P. Duval

Keyword(s):

Ice Core ◽

East Antarctica ◽

Deuterium Content ◽

Ice Crystal ◽

High Concentration ◽

Last Glacial Period ◽

Last Glacial ◽

Climatic Record ◽

Ice Crystal Size ◽

The Last Glacial

Deuterium content, microparticle concentration, ice crystal size and bubble concentration have been studied along an 82 m ice core drilled down to the bedrock in the ice-sheet margin in East Antarctica. The Last Glacial Maximum (LGM) is distinctly marked by low deuterium content, high concentration of microparticles, small ice crystals and high bubble concentrations. This core covers a significant part of the Last Glacial Period with ice from a warmer period recovered around a depth of 60 m.

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