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Publications
Publications (292)
The EPICA (European Project for Ice Coring in Antarctica) Dome C (EDC) ice core drilling in East Antarctica reaches a depth of 3260 m. The reference EDC chronology, the AICC2012 (Antarctic Ice Core Chronology 2012), provides an age vs. depth relationship covering the last 800 kyr (thousands of years), with an absolute uncertainty rising up to 8000...
Seasonal temperature reconstructions from ice cores are missing over glacial-interglacial timescales, preventing a good understanding of the driving factors of Antarctic past climate changes. Here the total air content (TAC) record from an Antarctic ice core is analyzed over the last 440 thousand of years (ka). While the water isotopic record, trac...
The EPICA (European Project for Ice Coring in Antarctica) Dome C (EDC) ice core drilling in East Antarctica reaches a depth of 3260 m. The reference EDC chronology (AICC2012) provides an age vs depth relationship covering the last 800 kyr (thousands of years) with an absolute uncertainty rising up to 8,000 years at the bottom of the ice core. The o...
In 1980, a method was found to determine the amount of carbon dioxide in ancient air trapped in polar ice — providing direct evidence that CO2 is coupled to climate, and affects global temperatures in the past, present and future. In 1980, a method was found to determine the amount of carbon dioxide in ancient air trapped in polar ice — providing d...
Nature has been continuously sampling the atmosphere at the surface of Antarctica throughout the ages. Atmospheric gases trapped in Antarctic ice provide the most direct record of changes in greenhouse gas levels during the past 800,000 years. The best-documented and reliable trace-gas records are for CO2 and CH4, and Antarctic ice is the key playe...
The last deglaciation, which occurred from 18 000 to 11 000 years ago, is the most recent large natural climatic variation of global extent. With accurately dated paleoclimate records, we can investigate the timings of related variables in the climate system during this major transition. Here, we use an accurate relative chronology to compare tempe...
The chronologies of deep polar ice cores are vital to our understanding of how climate variables and atmospheric greenhouse gas concentrations interacted over the last 800,000 years. The most recent chronologies of the deepest Antarctc ice cores rely in part on proxies that follow the periodicities of Earth´s insolation, defined by its rotational a...
We analyzed helium and neon in 24 samples from between 3,607 and 3,767 m (i.e., down to 2 m above the lake-ice interface) of the accreted ice frozen to the ceiling of Lake Vostok. Within uncertainties, the neon budget of the lake is balanced, the neon supplied to the lake by the melting of glacier ice being compensated by the neon exported by lake...
The last deglaciation, which occurred from 18,000 to 11,000 years ago, is the most recent large natural climatic variation of global extent. With accurately dated paleoclimate records, we can investigate the timings of related variables in the climate system during this major transition. Here, we use an accurate relative chronology to compare regio...
To understand causal relationships in past climate variations, it is essential to have accurate chronologies of paleoclimate records. The last deglaciation, which occurred from 18 000 to 11 000 years ago, is especially interesting, since it is the most recent large climatic variation of global extent. Ice cores in Antarctica provide important paleo...
Wavelets transform has proven to be a very important tool in statistics precisely in regression problems and density estimation of independent data. When we use wavelet analysis on two time series which are linked in some way, some interesting statistical properties appear like local average covariation of the series and coherence phase relationshi...
Deep drilling at the Vostok Station has reached the surface of subglacial Lake Vostok (LV) twice-in February 2012 and January 2015. As a result, three replicate cores from boreholes 5G-1, 5G-2 and 5G-3 became available for detailed and revalidation analyses of the 230 m thickness of the accreted ice, down to its contact with water at 3769 m below t...
Marine records indicate a dramatic change in the predominant periodicity of climate variability, from about 40 ka to about 100 ka around one million years ago. The reason for this major climatic shift, which is called the Mid-Pleistocene Transition or MPT, remains unknown – and is of great interest to the climate scientist. Could the core of the ol...
Interglacials, including the present (Holocene) period, are warm, low land-ice extent (high sea?level), end members of glacial cycles. Based on a sea-level definition, we identify eleven interglacials in the last 800,000 years, a result that is robust to alternative definitions. Data compilations suggest that, despite spatial heterogeneity, Marine...
Over the last 25 years, the ice core record has provided a unique and precious archive of past changes in three important greenhouse gases: carbon dioxide CO2, methane CH4 and nitrous oxide N2O. Recovering the Vostok ice core has played a major role, being the first ice record showing the variations of CO2 and CH4 during a full glacial-interglacial...
The end of the Last Glacial Maximum (Termination I), roughly 20 thousand years ago (ka), was marked by cooling in the Northern Hemisphere, a weakening of the Asian monsoon, a rise in atmospheric CO2 concentrations and warming over Antarctica. The sequence of events associated with the previous glacial–interglacial transition (Termination II), rough...
An accurate and coherent chronological frame-work is essential for the interpretation of climatic and envi-ronmental records obtained from deep polar ice cores. Un-til now, one common ice core age scale had been devel-oped based on an inverse dating method (Datice), combin-ing glaciological modelling with absolute and stratigraphic markers between...
Two ice cores recovered from the Himalayan East Rongbuk (ER) Glacier on
the northeast saddle of Mt. Qomolangma (Everest) (28° 01' N, 86°
58' E, 6518 m a.s.l.) give access to a tentative record of past
Himalayan atmospheric mixing ratio of CH4 spanning the past
1200 yr. The major part of the record is affected by artefacts probably
due to in-situ pr...
No Leader to Follow
Changes in the concentration of atmospheric CO 2 and surface air temperature are closely related. However, temperature can influence atmospheric CO 2 as well as be influenced by it. Studies of polar ice cores have concluded that temperature increases during periods of rapid warming have preceded increases in CO 2 by hundreds of...
Efforts to extract a Greenland ice core with a complete record of the Eemian interglacial (130,000 to 115,000 years ago) have until now been unsuccessful. The response of the Greenland ice sheet to the warmer-than-present climate of the Eemian has thus remained unclear. Here we present the new North Greenland Eemian Ice Drilling (‘NEEM’) ice core a...
Understanding the role of atmospheric CO2 during past climate changes requires clear knowledge of how it varies in time relative to temperature. Antarctic ice cores preserve highly resolved records of atmospheric CO2 and Antarctic temperature for the past 800,000 years. Here we propose a revised relative age scale for the concentration of atmospher...
An accurate and coherent chronological framework is essential for the interpretation of
climatic and environmental records obtained from deep polar ice cores. Until now, one
common ice core age scale has been developed based on an inverse dating method
5 (Datice) combining glaciological modelling with absolute and stratigraphic markers between
4 ic...
Differences in the duration of interglacials have long been apparent in palaeoclimate records of the Late and Middle Pleistocene. However, a systematic evaluation of such differences has been hampered by the lack of a metric that can be applied consistently through time and by difficulties in separating the local from the global component in variou...
Differences in the duration of interglacials have long been apparent in palaeoclimate records of the Late and Middle Pleistocene. However, a systematic evaluation of such differences has been hampered by the lack of a metric that can be applied consistently through time and by difficulties in separating the local from the global component in variou...
A new method of dating the long glacial-interglacial ice core records
has emerged during the last 10 years. It is based on properties measured
on the air extracted from the ice that are used as proxies of local
summer insolation. This dating method is referred to as "local orbital
tuning dating". It's an almost absolute dating, providing we better...
Precise ice cores chronologies are essential to better understand the
mechanisms linking climate change to orbital and greenhouse gases
concentration forcing. A tool for ice core dating (DATICE [developed by
Lemieux-Dudon et al., 2010] permits to generate a common time-scale
integrating relative and absolute dating constraints on different ice
core...
Based on a composite of several measurement series performed on ice samples stored at -25 degrees C or -50 degrees C, we present and discuss the first delta O-2/N-2 record of trapped air from the EPICA Dome C (EDC) ice core covering the period between 300 and 800 ka (thousands of years before present). The samples stored at -25 degrees C show clear...
The potential to access an ice core chronology tuned on local insolation has been demonstrated for the first time in the work of M. Bender (2002) linking the variations of O2/N2 ratios in the air trapped in the Vostok ice with local (78°S) summertime insolation. More recently, it has been shown that the long-term changes in air content, V, recorded...
Based on a composite of several measurement series performed on ice samples stored at -25 °C or -50 °C, we present and discuss the first deltaO2/N2 record of trapped air from the EPICA Dome C (EDC) ice core covering the period between 300 and 800 ka (thousands of years before present). The samples stored at -25 °C show clear gas loss affecting the...
We present here the first deltaO2/N2 record of trapped air from the EPICA Dome C (EDC) ice core, covering the period between 300 and 800 ka, which includes two periods of low orbital eccentricity. This record is a composite of several measurement series performed on ice samples stored at -25°C or -50°C. The samples stored at -25°C show clear gas lo...
The reconstruction of delta13CO2 using Antarctic ice cores promises a deeper understanding on the causes of past atmospheric CO2 changes. Previous measurements on the Taylor Dome ice core over the last 30,000 years (Smith et al., 1999) indicated marine processes to be dominating the significant delta13CO2 changes over the transition, whereas glacia...
The largest natural increases in atmospheric CO2 concentration as recorded in ice cores occur when the Earth climate abruptly shifts from a glacial to an interglacial state. Open questions remain regarding the processes at play, the sequences of events and their similarities along different glacial–interglacial transitions. Here we provide new comb...
The causes of the ∼80 ppmv increase of atmospheric carbon dioxide (CO2) during the last glacial-interglacial climatic transition remain debated. We analyzed the parallel evolution of CO2 and its stable carbon isotopic ratio (δ13CO2) in the European Project for Ice Coring in Antarctica (EPICA) Dome C ice core to bring additional constraints. Agreein...
Different measurements have been performed on ice samples taken from a drilling about 100 meters deep in the coastal region of Terre Adelie (Antarctica); the mean temperature in the hole was approximately −10°C. The results show that the pressure of gaz inclusions and the density of the ice increase with the depth. The values of the density increas...
Recent progress in the reconstruction of atmospheric CO2 records from Antarctic ice cores has allowed for the documentation of natural CO2 variations on orbital time scales over the last up to 800,000 years and for the resolution of millennial CO2 variations during the last glacial cycle in unprecedented detail. This has shown that atmospheric CO2...
Entering an era of global warming, the stability of the Greenland ice sheet (GIS) is a major concern, especially in the light of new evidence of rapidly changing flow and melt conditions at the GIS margins. Hence it is imperative to advance our understanding of GIS dynamics by studying the response of the GIS to past climatic change. In this study...
Earth's climate has progressively cooled over the past 3 million years with a concomitant expansion of continental ice volume. This global trend towards increasingly severe and extended ice ages has nevertheless been repeatedly interrupted by relatively mild/warm interglacial intervals such as the one that has characterized the past 11,000 years. P...
Earth's climate has progressively cooled over the past 3 million years with a concomitant expansion of continental ice volume. This global trend towards increasingly severe and extended ice ages has nevertheless been repeatedly interrupted by relatively mild/warm interglacial intervals such as the one that has characterized the past 11,000 years. P...
On entering an era of global warming, the stability of the Greenland ice sheet (GIS) is an important concern, especially in the light of new evidence of rapidly changing flow and melt conditions at the GIS margins. Studying the response of the GIS to past climatic change may help to advance our understanding of GIS dynamics. The previous interpreta...
The analysis of air bubbles trapped in polar ice permits the reconstruction of atmospheric components over various timescales. Past evolution of greenhouse gases, such as carbon dioxide (CO 2), lies on the frontline of paleorecords understanding. Within this study, the glacial – interglacial oscillations of CO 2 will be examined for the last 160,00...
Constraints on the atmospheric CO2 deglacial rise based on its delta13CO2 evolution
CO2 measurements on the EPICA DML ice core in depth levels just below the bubble ice - clathrate ice transition zone (> 1230 m) reveal variations of up to 25 ppmv within centimeters corresponding to a few years. Similarly unrealistic results are found at this depth region of the Dome C and the Talos Dome ice cores. Since all known processes alterin...
We are investigating the biological content (biomass and microbial diversity of Aeolian origin) of EPICA ice core within the frame of EPICA Microbiology consortium*. Two ice core sections were selected from EPICA Dome C and Droning Maud Land, both from LGM and Holocene. Preliminary measurements of DOC (dissolved organic content) and microbial cell...
An accurate chronology of ice cores is needed for interpreting the
paleoclimatic record and understanding the relation between insolation
and climate. A new domain of research in this area has been initially
stimulated by the work of M. Bender (2002) linking the record of O2/N2
ratio in the air trapped in the Vostok ice with the local insolation.
M...
This article was submitted without an abstract, please refer to the full-text PDF file.
This article was submitted without an abstract, please refer to the full-text PDF file.
This article was submitted without an abstract, please refer to the full-text PDF file.
This article was submitted without an abstract, please refer to the full-text PDF file.
in Cordis Focus Thematic on European Polar Research
Changes in past atmospheric carbon dioxide concentrations can be determined by measuring the composition of air trapped in ice cores from Antarctica. So far, the Antarctic Vostok and EPICA Dome C ice cores have provided a composite record of atmospheric carbon dioxide levels over the past 650,000 years. Here we present results of the lowest 200 m o...
The behaviour of CO2 and CH4 during MIS 11 has been of particular interest, in particular in the light of Ruddiman's suggestion (2003) that the rise of these greenhouse trace gases during a large part of the Holocene has been of anthropogenic origin, in contrast with the traditional view of a limited anthropogenic influence starting with the indust...
Changes in past atmospheric carbon dioxide concentrations can be determined by measuring the composition of air trapped in ice cores from Antarctica. So far, the Antarctic Vostok and EPICA Dome C ice cores have provided a composite record of atmospheric carbon dioxide levels over the past 650,000 years. Here we present results of the lowest 200 m o...
Atmospheric methane is an important greenhouse gas and a sensitive indicator of climate change and millennial-scale temperature variability. Its concentrations over the past 650,000 years have varied between approximately 350 and approximately 800 parts per 10(9) by volume (p.p.b.v.) during glacial and interglacial periods, respectively. In compari...
We present a Pacific benthic delta13C stack of the last 800 kyr and compare it with atmospheric CO2 concentration [Lüthi et al., 2008], Antarctic temperature [Jouzel et al., 2007], and benthic delta18O [Lisiecki and Raymo, 2005]. We find that carbon cycle proxies delta13C and CO2 share some features which consistently differ from records of Antarct...
The deep ice core recovered from Dome Concordia in the framework of EPICA, the European Project for Ice Coring in Antarctica, has extended the record of Antarctic climate history back to 800,000 years [Jouzel et al., 2007]. We present the current status of measurements of CO2, CH4 and N2O on air trapped in the bubbles of the Dome C ice core. CO2 is...
An accurate chronology of ice cores is still needed for interpreting the paleoclimatic record and to understand the relation between insolation and climate. A new domain of research in this area has been stimulated by the work of M. Bender linking the record of N2/O2 ratio in the air trapped in the ice with the local insolation. Here we investigate...
A high-resolution deuterium profile is now available along the entire European Project for Ice Coring in Antarctica Dome C
ice core, extending this climate record back to marine isotope stage 20.2, ∼800,000 years ago. Experiments performed with
an atmospheric general circulation model including water isotopes support its temperature interpretation....
The EPICA (European Project for Ice Coring in Antarctica) Dome C drilling in East Antarctica has now been completed to a depth of 3260 m, at only a few meters above bedrock. Here we present the new EDC3 chronology, which is based on the use of 1) a snow accumulation and mechan-ical flow model, and 2) a set of independent age markers along the core....
Two Himalayan ice cores display a factor-two decreasing trend of air content over the past two millennia, in contrast to the relatively stable values in Greenland and Antarctica ice cores over the same period. Because the air content can be related with the relative frequency and intensity of melt phenomena, its variations along the Himalayan ice c...
Ice-cores dating is an essential issue to analyse data measured on ice samples in order to contribute to Earth climate history decephering. Several methods have been already implemented. Each method brings some valuable but incomplete information for building the depth-age relationship of an ice-core: some methods only apply on the top part of the...
Air content of polar ice, V, depends primarily on air pressure, temperature and pore volume at close-off prevailing at the site of ice formation. Here we present the recently measured V record of the EPICA DC (EDC) Antarctic ice core covering the last 650,000 years. The first 440,000 years remarkably displays the fundamental Milankovitch orbital fr...
Ice cores provide the only direct way of determining past concentrations
of atmospheric CO2. In the absence of artefacts (which is generally the
case in Antarctic ice cores), the air extracted from ice gives a direct
measure of the CO2 concentration. The 420,000 year (420 kyr) ice core
record from Vostok (Petit et al., Nature, 1999) has now been ex...
Precise knowledge of the phase relationship between climate changes in the two hemispheres is a key for understanding the Earth's climate dynamics. For the last glacial period, ice core studies1, 2 have revealed strong coupling of the largest millennial-scale warm events in Antarctica with the longest Dansgaard–Oeschger events in Greenland3, 4, 5 t...
Ice cores provide unique archives of past climate and environmental changes based only on physical processes. Quantitative temperature reconstructions are essential for the comparison between ice core records and climate models. We give an overview of the methods that have been developed to reconstruct past local temperatures from deep ice cores an...