Fabrice Lambert - Profile on Academia.edu (original) (raw)
Papers by Fabrice Lambert
A comparison of centennial and millennial climatic variations during the Holocene and the Marine Isotope Stage 11
Southern Hemisphere oscillations during the past 800,000 years evidenced in the EPICA high-resolution dust record
Quaternary International, 2012
Doklady Earth Sciences, 2010
This article is a review of the science goals and activities initiated within the framework of th... more This article is a review of the science goals and activities initiated within the framework of the
Pollution and its Impacts on the South American Cryosphere (PISAC) initiative. Air pollution associated
with biomass burning and urban emissions affects extensive areas of South America. We focus on black
carbon (BC) aerosol and its impacts on air quality, water availability, and climate, with an emphasis on the
Andean cryosphere. BC is one of the key short-lived climate pollutants that is a topic of growing interest
for near-term mitigation of these issues. Limited scientific evidence indicates that the Andean cryosphere
has already responded to climate change with receding glaciers and snow cover, which directly affect
water resources, agriculture, and energy production in the Andean region of South America. Despite the
paucity of systematic observations along the Andes, a few studies have detected BC on snow and glaciers
in the Andes. These, in addition to existing and projected emissions and weather patterns, suggest a possible
contribution of BC to the observed retreat of the Andean cryosphere. Here we provide an overview
of the current understanding of these issues from scientific and policy perspectives, and propose strategic
expansions to the relevant measurement infrastructure in the region.
Reconstruction of Holocene and LGM atmospheric dust aerosol concentrations from paleoclimatic archives
ABSTRACT Atmospheric mineral dust aerosols affect the global climate by scattering and absorbing ... more ABSTRACT Atmospheric mineral dust aerosols affect the global climate by scattering and absorbing solar and thermal radiation, as well as providing micronutrients to primary production regions. Present and past global atmospheric dust concentrations have so far been deduced from model simulations. We present a new estimate of atmospheric dust concentrations and dust aerosol radiative forcing based on measurements of dust deposition in paleoclimate archives (mainly the DIRTMAP 3 dataset). Using a kriging technique, the dust deposition data from terrestrial, marine, and ice core records was interpolated to a global grid for both average Holocene and Last Glacial Maximum climatic conditions. By combining the data with some parameters from dust models we reconstructed Holocene and LGM surface and atmospheric dust concentrations. This new dataset's dust concentrations and radiative forcing is compared to the results from dust model simulations. We show how this new dataset can be used by calculating dust radiative forcing in polar areas. Dust appears to play an important role in the polar amplification phenomenon during dusty times by cooling down the surface and heating the upper atmospheric layers.
Testing the observed dust-climate relationship over the past 800’000 years from the EPICA Dome C ice core within the assumption of a semi empirical dust model: application for detecting outliers and for refining the ice core chronology
New insights on Antarctic Quaternary climate from high–resolution aeolian dust data from the EPICA–Dome C ice core
Eemian and penultimate transition reflected in the chemical ice core record from Dome C
Within the scope of the European Project for Ice Coring in Antarctica (EPICA) chemical analyses h... more Within the scope of the European Project for Ice Coring in Antarctica (EPICA) chemical analyses have been done along the Dome C ice core. Among other substances, Ca2+, dust, Na+, NH_4{}+, NO_3{}- and electrolytical melt water conductivity have been measured at 1 cm resolution with the Bern Continuous Flow Analysis (CFA) system. Here we present new data from the Eemian and the preceding transition covering an age interval from approximately 180 kyr to 110 kyr before present. This sequence is compared with the Holocene and the last transition, mainly with emphasis on terrestrial and marine tracers. Concentration levels for the two periods compare quite well, but the general shape differs considerably. The changes in dust input to Dome C seemed to have been much more abrupt during the penultimate transition than during the last transition (18 to 15 kyr BP). This may reflect different conditions and/or processes in the dust source region.
EPICA Dome-C ice core: Extending the dust record over tha last 730 ka
Northern-Southern Hemisphere Comparison of Aeolian Dust Records Over the Last 800 Kyr
The 3130m-deep ice core from Dome C obtained in the frame of the European Project of Ice Coring i... more The 3130m-deep ice core from Dome C obtained in the frame of the European Project of Ice Coring in Antarctica (EPICA) depicts 8 glacial periods. Here we present the results of dust content and we extend the record down to 3200 m, corresponding to circa 800 kyr B.P. The dust has been measured by using two independent techniques: a laser system deployed on the field and used for continuous measurements and counting in laboratory by using Coulter Counter (Multisizer II) on discrete samples from about 1200 levels. The laser and Coulter EPICA dust profiles are well consistent. Amongst Antarctic records, over the last 4 climate cycles, the EPICA-Dome C dust record mimics the Vostok one and several dust events could be confidently used as stratigraphic markers since the records share the same dust sources. The high dust input (up to a factor 50 with respect to present time) characterising the high latitude records during glacial climate is linked to the synergetic effect of several factors...
Climate of the Past Discussions, 2011
Ice core data from Antarctica provide detailed insights into the characteristics of past climate,... more Ice core data from Antarctica provide detailed insights into the characteristics of past climate, atmospheric circulation, as well as changes in the aerosol load of the atmosphere. We present high-resolution records of soluble calcium (Ca 2+ ), non-sea-salt soluble calcium (nssCa 2+ ), and insoluble mineral aerosol dust from the East Antarctic 5 15 soluble calcium content of dust particles, possibly due to a more acidic atmosphere during interglacials. The ratio of nssCa 2+ to dust is dependent on the dust concentration itself. A simple mixing of two dust end members for glacial and interglacial conditions with nssCa 2+ to dust ratios of 0.045 and approximately 0.3, respectively, can explain the overall temporal change in the nssCa 2+ to dust ratio over time. 20
Nature Climate Change, 2013
Changes in global temperature are generally more marked in high than in low latitudes, an effect ... more Changes in global temperature are generally more marked in high than in low latitudes, an effect referred to as polar amplification 1-3 . Model simulations of future climate suggest a marked response of high-latitude climate due to elevated greenhouse-gas concentrations and associated albedo feedbacks 4 . However, most climate models struggle to reproduce the amplitude of polar temperature change observed in palaeoclimatic archives 3 and may carry this bias into future predictions. With the example of mineral dust we show that some atmospheric aerosols experience an amplified highlatitude response to global changes as well, a phenomenon generally not captured by the models. Using a synthesis of observational and model data we reconstruct atmospheric dust concentrations for Holocene and Last Glacial Maximum (LGM) conditions. Radiative forcing calculations based on our new dust concentration reconstructions suggest that the impact of aerosols in polar areas is underestimated in model simulations for dustier-than-modern conditions. In the future, some simulations predict an increase in aridity in dust source areas 5 . Other aerosols such as black carbon and sulphates are likely to increase as well 6,7 . We therefore suggest that the inclusion of the amplified high-latitude response of aerosols in atmospheric models would improve the assessment of LGM and future polar amplification.
Quaternary Science Reviews, 2010
Along the EPICA Dome C ice core, we measured concentrations of different water-soluble aerosol co... more Along the EPICA Dome C ice core, we measured concentrations of different water-soluble aerosol constituents and deduced total depositional flux records. Here we present high-resolution sodium, calcium, ammonium and nitrate data covering the last 173,000 years. The first three of these species are passive tracers and reveal source and long-range transport changes whereas nitrate is deposited reversibly. However, it can be used to check isotope-derived accumulation rate estimates, a prerequisite to calculate total depositional fluxes. During the last two transitions from glacial to interglacial periods, changes in the total depositional flux differ strongly for different aerosol species. The largest changes are observed in the terrestrial aerosol proxy non-sea salt calcium, only moderate changes occur in the marine sea salt indicator sodium, while ammonium, a proxy for marine bioproductivity, remains rather constant. In agreement with previous studies, we find that only considerable glacial-interglacial changes at both, the terrestrial and the marine sea salt aerosol source can explain the observed pronounced changes. The unprecedented high-resolution of our data allows for the first time the examination of decadal variability back to the penultimate glacial period. On the one hand, we find occasional fast shifts occurring within a few years; here we present such an event in the calcium record from the penultimate glacial period. On the other hand, we examine variation coefficients and pairwise correlation coefficients, both determined in 200-year windows. They generally reveal only moderate changes. During glacial periods, slightly lower variation coefficients are found, concurrent with slightly higher correlation coefficients, which points to a more uniform and stronger coupled atmospheric long-range transport of the different aerosol species to the East Antarctic Plateau and less influence of cyclonic activities during cold periods. The opposite is observed for interglacial periods with probably even reinforced importance of cyclonic influences during the Last Interglacial period, the Marine Isotope Stage 5.5. This period reveals no evidence for abrupt climatic changes in any of the species, however, the marine sea salt aerosol indicator sodium shows a distinct minimum followed by a pronounced increase. This pattern is explained by significantly reduced sea ice production in the Indian Southern Ocean sector, which is believed to be the dominant source of sodium deposited in Dome C during warm periods.
Quaternary Science Reviews, 2010
The EPICA ice core from Dome C extends 3259 m in depth, and encompasses 800 ka of datable and seq... more The EPICA ice core from Dome C extends 3259 m in depth, and encompasses 800 ka of datable and sequential ice. Numerous chemical species have been measured along the length of the cores. Here we concentrate on interpreting the main low-resolution patterns of major ions. We extend the published record for non-sea-salt calcium, sea-salt sodium and non-sea-salt sulfate flux to 800 ka. The non-sea-salt calcium record confirms that terrestrial dust originating from South America closely mirrored Antarctic climate, both at orbital and millennial timescales. A major cause of the main trends is most likely climate in southern South America, which could be sensitive to subtle changes in atmospheric circulation. Seasalt sodium also follows temperature, but with a threshold at low temperature. We re-examine the use of sodium as a sea ice proxy, concluding that it is probably reflecting extent, with high salt concentrations reflecting larger ice extents. With this interpretation, the sodium flux record indicates low ice extent operating as an amplifier in warm interglacials. Non-sea-salt sulfate flux is almost constant along the core, confirming the lack of change in marine productivity (for sulfur-producing organisms) in the areas of the Southern Ocean contributing to the flux at Dome C. For the first time we also present long records of reversible species such as nitrate and chloride, and show that the pattern of post-depositional losses described for shallower ice is maintained in older ice. It appears possible to use these concentrations to constrain snow accumulation rates in interglacial ice at this site, and the results suggest a possible correction to accumulation rates in one early interglacial. Taken together the chemistry records offer a number of constraints on the way the Earth system combined to give the major climate fluctuations of the late Quaternary period.
Nature, 2008
Dust can affect the radiative balance of the atmosphere by absorbing or reflecting incoming solar... more Dust can affect the radiative balance of the atmosphere by absorbing or reflecting incoming solar radiation 1 ; it can also be a source of micronutrients, such as iron, to the ocean 2 . It has been suggested that production, transport and deposition of dust is influenced by climatic changes on glacial2interglacial timescales 3-6 . Here we present a high-resolution record of aeolian dust from the EPICA Dome C ice core in East Antarctica, which provides an undisturbed climate sequence over the past eight climatic cycles 7,8 . We find that there is a significant correlation between dust flux and temperature records during glacial periods that is absent during interglacial periods. Our data suggest that dust flux is increasingly correlated with Antarctic temperature as the climate becomes colder. We interpret this as progressive coupling of the climates of Antarctic and lower latitudes. Limited changes in glacial2interglacial atmospheric transport time suggest that the sources and lifetime of dust are the main factors controlling the high glacial dust input. We propose that the observed 25-fold increase in glacial dust flux over all eight glacial periods can be attributed to a strengthening of South American dust sources, together with a longer lifetime for atmospheric dust particles in the upper troposphere resulting from a reduced hydrological cycle during the ice ages.
Journal of Geophysical Research, 2006
Environmental Science & Technology, 2008
To improve quantitative interpretation of ice core aeolian dust records, a systematic methodologi... more To improve quantitative interpretation of ice core aeolian dust records, a systematic methodological comparison was made. This involved methods for water-insoluble particle counting (Coulter counter and laser-sensing particle detector), soluble ion analysis (ion chromatography and continuous flow analysis), elemental analysis (inductively coupled plasma mass spectroscopy at pH 1 and after full acid digestion), and waterinsoluble elemental analysis (proton induced X-ray emission). Antarctic ice core samples covering the last deglaciation from the EPICA Dome C (EDC) and the EPICA Dronning Maud Land (EDML) cores were used. All methods correlate very well among each other, but the ratios of glacial age to Holocene concentrations, which are typically a factor ∼100, differ between the methods by up to a factor of 2 with insoluble particles showing the largest variability. The recovery of ICP-MS measurements depends on the digestion method and is different for different elements and during different climatic periods. EDC and EDML samples have similar dust composition, which suggests a common dust source or a common mixture of sources for the two sites. The analyzed samples further reveal a change of dust composition during the last deglaciation.
![Research paper thumbnail of Erratum to “Reconstruction of millennial changes in dust emission, transport and regional sea ice coverage using the deep EPICA ice cores from the Atlantic and Indian Ocean sector of Antarctica” [Earth Planet. Sci. Lett. 260 (2007) 340–354]](https://attachments.academia-assets.com/42144073/thumbnails/1.jpg)
](Earth and Planetary Science Letters, 2007
Continuous sea salt and mineral dust aerosol records have been studied on the two EPICA (European... more Continuous sea salt and mineral dust aerosol records have been studied on the two EPICA (European Project for Ice Coring in Antarctica) deep ice cores. The joint use of these records from opposite sides of the East Antarctic plateau allows for an estimate of changes in dust transport and emission intensity as well as for the identification of regional differences in the sea salt aerosol source. The mineral dust flux records at both sites show a strong coherency over the last 150 kyr related to dust emission changes in the glacial Patagonian dust source with three times higher dust fluxes in the Atlantic compared to the Indian Ocean sector of the Southern Ocean (SO). Using a simple conceptual transport model this indicates that transport can explain only 40% of the atmospheric dust concentration changes in Antarctica, while factor 5-10 changes occurred. Accordingly, the main cause for the strong glacial dust flux changes in Antarctica must lie in environmental changes in Patagonia. Dust emissions, hence environmental conditions in Patagonia, were very similar during the last two glacials and interglacials, respectively, despite 2-4°C warmer temperatures recorded in Antarctica during the penultimate interglacial than today. 2-3 times higher sea salt fluxes found in both ice cores in the glacial compared to the Holocene are difficult to reconcile with a largely unchanged transport intensity and the distant open ocean source. The substantial glacial enhancements in sea salt aerosol fluxes can be readily explained assuming sea ice formation as the main sea salt aerosol source with a significantly larger expansion of (summer) sea ice in the Weddell Sea than in the Indian Ocean sector. During the penultimate interglacial, our sea salt records point to a 50% reduction of winter sea ice coverage compared to the Holocene both in the Indian and Atlantic Ocean sector of the SO. However, from 20 to 80 ka before present sea salt fluxes show only very subdued millennial changes despite pronounced temperature fluctuations, likely due to the large distance of the sea ice salt source to our drill sites.
A comparison of centennial and millennial climatic variations during the Holocene and the Marine Isotope Stage 11
Southern Hemisphere oscillations during the past 800,000 years evidenced in the EPICA high-resolution dust record
Quaternary International, 2012
Doklady Earth Sciences, 2010
This article is a review of the science goals and activities initiated within the framework of th... more This article is a review of the science goals and activities initiated within the framework of the
Pollution and its Impacts on the South American Cryosphere (PISAC) initiative. Air pollution associated
with biomass burning and urban emissions affects extensive areas of South America. We focus on black
carbon (BC) aerosol and its impacts on air quality, water availability, and climate, with an emphasis on the
Andean cryosphere. BC is one of the key short-lived climate pollutants that is a topic of growing interest
for near-term mitigation of these issues. Limited scientific evidence indicates that the Andean cryosphere
has already responded to climate change with receding glaciers and snow cover, which directly affect
water resources, agriculture, and energy production in the Andean region of South America. Despite the
paucity of systematic observations along the Andes, a few studies have detected BC on snow and glaciers
in the Andes. These, in addition to existing and projected emissions and weather patterns, suggest a possible
contribution of BC to the observed retreat of the Andean cryosphere. Here we provide an overview
of the current understanding of these issues from scientific and policy perspectives, and propose strategic
expansions to the relevant measurement infrastructure in the region.
Reconstruction of Holocene and LGM atmospheric dust aerosol concentrations from paleoclimatic archives
ABSTRACT Atmospheric mineral dust aerosols affect the global climate by scattering and absorbing ... more ABSTRACT Atmospheric mineral dust aerosols affect the global climate by scattering and absorbing solar and thermal radiation, as well as providing micronutrients to primary production regions. Present and past global atmospheric dust concentrations have so far been deduced from model simulations. We present a new estimate of atmospheric dust concentrations and dust aerosol radiative forcing based on measurements of dust deposition in paleoclimate archives (mainly the DIRTMAP 3 dataset). Using a kriging technique, the dust deposition data from terrestrial, marine, and ice core records was interpolated to a global grid for both average Holocene and Last Glacial Maximum climatic conditions. By combining the data with some parameters from dust models we reconstructed Holocene and LGM surface and atmospheric dust concentrations. This new dataset's dust concentrations and radiative forcing is compared to the results from dust model simulations. We show how this new dataset can be used by calculating dust radiative forcing in polar areas. Dust appears to play an important role in the polar amplification phenomenon during dusty times by cooling down the surface and heating the upper atmospheric layers.
Testing the observed dust-climate relationship over the past 800’000 years from the EPICA Dome C ice core within the assumption of a semi empirical dust model: application for detecting outliers and for refining the ice core chronology
New insights on Antarctic Quaternary climate from high–resolution aeolian dust data from the EPICA–Dome C ice core
Eemian and penultimate transition reflected in the chemical ice core record from Dome C
Within the scope of the European Project for Ice Coring in Antarctica (EPICA) chemical analyses h... more Within the scope of the European Project for Ice Coring in Antarctica (EPICA) chemical analyses have been done along the Dome C ice core. Among other substances, Ca2+, dust, Na+, NH_4{}+, NO_3{}- and electrolytical melt water conductivity have been measured at 1 cm resolution with the Bern Continuous Flow Analysis (CFA) system. Here we present new data from the Eemian and the preceding transition covering an age interval from approximately 180 kyr to 110 kyr before present. This sequence is compared with the Holocene and the last transition, mainly with emphasis on terrestrial and marine tracers. Concentration levels for the two periods compare quite well, but the general shape differs considerably. The changes in dust input to Dome C seemed to have been much more abrupt during the penultimate transition than during the last transition (18 to 15 kyr BP). This may reflect different conditions and/or processes in the dust source region.
EPICA Dome-C ice core: Extending the dust record over tha last 730 ka
Northern-Southern Hemisphere Comparison of Aeolian Dust Records Over the Last 800 Kyr
The 3130m-deep ice core from Dome C obtained in the frame of the European Project of Ice Coring i... more The 3130m-deep ice core from Dome C obtained in the frame of the European Project of Ice Coring in Antarctica (EPICA) depicts 8 glacial periods. Here we present the results of dust content and we extend the record down to 3200 m, corresponding to circa 800 kyr B.P. The dust has been measured by using two independent techniques: a laser system deployed on the field and used for continuous measurements and counting in laboratory by using Coulter Counter (Multisizer II) on discrete samples from about 1200 levels. The laser and Coulter EPICA dust profiles are well consistent. Amongst Antarctic records, over the last 4 climate cycles, the EPICA-Dome C dust record mimics the Vostok one and several dust events could be confidently used as stratigraphic markers since the records share the same dust sources. The high dust input (up to a factor 50 with respect to present time) characterising the high latitude records during glacial climate is linked to the synergetic effect of several factors...
Climate of the Past Discussions, 2011
Ice core data from Antarctica provide detailed insights into the characteristics of past climate,... more Ice core data from Antarctica provide detailed insights into the characteristics of past climate, atmospheric circulation, as well as changes in the aerosol load of the atmosphere. We present high-resolution records of soluble calcium (Ca 2+ ), non-sea-salt soluble calcium (nssCa 2+ ), and insoluble mineral aerosol dust from the East Antarctic 5 15 soluble calcium content of dust particles, possibly due to a more acidic atmosphere during interglacials. The ratio of nssCa 2+ to dust is dependent on the dust concentration itself. A simple mixing of two dust end members for glacial and interglacial conditions with nssCa 2+ to dust ratios of 0.045 and approximately 0.3, respectively, can explain the overall temporal change in the nssCa 2+ to dust ratio over time. 20
Nature Climate Change, 2013
Changes in global temperature are generally more marked in high than in low latitudes, an effect ... more Changes in global temperature are generally more marked in high than in low latitudes, an effect referred to as polar amplification 1-3 . Model simulations of future climate suggest a marked response of high-latitude climate due to elevated greenhouse-gas concentrations and associated albedo feedbacks 4 . However, most climate models struggle to reproduce the amplitude of polar temperature change observed in palaeoclimatic archives 3 and may carry this bias into future predictions. With the example of mineral dust we show that some atmospheric aerosols experience an amplified highlatitude response to global changes as well, a phenomenon generally not captured by the models. Using a synthesis of observational and model data we reconstruct atmospheric dust concentrations for Holocene and Last Glacial Maximum (LGM) conditions. Radiative forcing calculations based on our new dust concentration reconstructions suggest that the impact of aerosols in polar areas is underestimated in model simulations for dustier-than-modern conditions. In the future, some simulations predict an increase in aridity in dust source areas 5 . Other aerosols such as black carbon and sulphates are likely to increase as well 6,7 . We therefore suggest that the inclusion of the amplified high-latitude response of aerosols in atmospheric models would improve the assessment of LGM and future polar amplification.
Quaternary Science Reviews, 2010
Along the EPICA Dome C ice core, we measured concentrations of different water-soluble aerosol co... more Along the EPICA Dome C ice core, we measured concentrations of different water-soluble aerosol constituents and deduced total depositional flux records. Here we present high-resolution sodium, calcium, ammonium and nitrate data covering the last 173,000 years. The first three of these species are passive tracers and reveal source and long-range transport changes whereas nitrate is deposited reversibly. However, it can be used to check isotope-derived accumulation rate estimates, a prerequisite to calculate total depositional fluxes. During the last two transitions from glacial to interglacial periods, changes in the total depositional flux differ strongly for different aerosol species. The largest changes are observed in the terrestrial aerosol proxy non-sea salt calcium, only moderate changes occur in the marine sea salt indicator sodium, while ammonium, a proxy for marine bioproductivity, remains rather constant. In agreement with previous studies, we find that only considerable glacial-interglacial changes at both, the terrestrial and the marine sea salt aerosol source can explain the observed pronounced changes. The unprecedented high-resolution of our data allows for the first time the examination of decadal variability back to the penultimate glacial period. On the one hand, we find occasional fast shifts occurring within a few years; here we present such an event in the calcium record from the penultimate glacial period. On the other hand, we examine variation coefficients and pairwise correlation coefficients, both determined in 200-year windows. They generally reveal only moderate changes. During glacial periods, slightly lower variation coefficients are found, concurrent with slightly higher correlation coefficients, which points to a more uniform and stronger coupled atmospheric long-range transport of the different aerosol species to the East Antarctic Plateau and less influence of cyclonic activities during cold periods. The opposite is observed for interglacial periods with probably even reinforced importance of cyclonic influences during the Last Interglacial period, the Marine Isotope Stage 5.5. This period reveals no evidence for abrupt climatic changes in any of the species, however, the marine sea salt aerosol indicator sodium shows a distinct minimum followed by a pronounced increase. This pattern is explained by significantly reduced sea ice production in the Indian Southern Ocean sector, which is believed to be the dominant source of sodium deposited in Dome C during warm periods.
Quaternary Science Reviews, 2010
The EPICA ice core from Dome C extends 3259 m in depth, and encompasses 800 ka of datable and seq... more The EPICA ice core from Dome C extends 3259 m in depth, and encompasses 800 ka of datable and sequential ice. Numerous chemical species have been measured along the length of the cores. Here we concentrate on interpreting the main low-resolution patterns of major ions. We extend the published record for non-sea-salt calcium, sea-salt sodium and non-sea-salt sulfate flux to 800 ka. The non-sea-salt calcium record confirms that terrestrial dust originating from South America closely mirrored Antarctic climate, both at orbital and millennial timescales. A major cause of the main trends is most likely climate in southern South America, which could be sensitive to subtle changes in atmospheric circulation. Seasalt sodium also follows temperature, but with a threshold at low temperature. We re-examine the use of sodium as a sea ice proxy, concluding that it is probably reflecting extent, with high salt concentrations reflecting larger ice extents. With this interpretation, the sodium flux record indicates low ice extent operating as an amplifier in warm interglacials. Non-sea-salt sulfate flux is almost constant along the core, confirming the lack of change in marine productivity (for sulfur-producing organisms) in the areas of the Southern Ocean contributing to the flux at Dome C. For the first time we also present long records of reversible species such as nitrate and chloride, and show that the pattern of post-depositional losses described for shallower ice is maintained in older ice. It appears possible to use these concentrations to constrain snow accumulation rates in interglacial ice at this site, and the results suggest a possible correction to accumulation rates in one early interglacial. Taken together the chemistry records offer a number of constraints on the way the Earth system combined to give the major climate fluctuations of the late Quaternary period.
Nature, 2008
Dust can affect the radiative balance of the atmosphere by absorbing or reflecting incoming solar... more Dust can affect the radiative balance of the atmosphere by absorbing or reflecting incoming solar radiation 1 ; it can also be a source of micronutrients, such as iron, to the ocean 2 . It has been suggested that production, transport and deposition of dust is influenced by climatic changes on glacial2interglacial timescales 3-6 . Here we present a high-resolution record of aeolian dust from the EPICA Dome C ice core in East Antarctica, which provides an undisturbed climate sequence over the past eight climatic cycles 7,8 . We find that there is a significant correlation between dust flux and temperature records during glacial periods that is absent during interglacial periods. Our data suggest that dust flux is increasingly correlated with Antarctic temperature as the climate becomes colder. We interpret this as progressive coupling of the climates of Antarctic and lower latitudes. Limited changes in glacial2interglacial atmospheric transport time suggest that the sources and lifetime of dust are the main factors controlling the high glacial dust input. We propose that the observed 25-fold increase in glacial dust flux over all eight glacial periods can be attributed to a strengthening of South American dust sources, together with a longer lifetime for atmospheric dust particles in the upper troposphere resulting from a reduced hydrological cycle during the ice ages.
Journal of Geophysical Research, 2006
Environmental Science & Technology, 2008
To improve quantitative interpretation of ice core aeolian dust records, a systematic methodologi... more To improve quantitative interpretation of ice core aeolian dust records, a systematic methodological comparison was made. This involved methods for water-insoluble particle counting (Coulter counter and laser-sensing particle detector), soluble ion analysis (ion chromatography and continuous flow analysis), elemental analysis (inductively coupled plasma mass spectroscopy at pH 1 and after full acid digestion), and waterinsoluble elemental analysis (proton induced X-ray emission). Antarctic ice core samples covering the last deglaciation from the EPICA Dome C (EDC) and the EPICA Dronning Maud Land (EDML) cores were used. All methods correlate very well among each other, but the ratios of glacial age to Holocene concentrations, which are typically a factor ∼100, differ between the methods by up to a factor of 2 with insoluble particles showing the largest variability. The recovery of ICP-MS measurements depends on the digestion method and is different for different elements and during different climatic periods. EDC and EDML samples have similar dust composition, which suggests a common dust source or a common mixture of sources for the two sites. The analyzed samples further reveal a change of dust composition during the last deglaciation.
Earth and Planetary Science Letters, 2007
Continuous sea salt and mineral dust aerosol records have been studied on the two EPICA (European... more Continuous sea salt and mineral dust aerosol records have been studied on the two EPICA (European Project for Ice Coring in Antarctica) deep ice cores. The joint use of these records from opposite sides of the East Antarctic plateau allows for an estimate of changes in dust transport and emission intensity as well as for the identification of regional differences in the sea salt aerosol source. The mineral dust flux records at both sites show a strong coherency over the last 150 kyr related to dust emission changes in the glacial Patagonian dust source with three times higher dust fluxes in the Atlantic compared to the Indian Ocean sector of the Southern Ocean (SO). Using a simple conceptual transport model this indicates that transport can explain only 40% of the atmospheric dust concentration changes in Antarctica, while factor 5-10 changes occurred. Accordingly, the main cause for the strong glacial dust flux changes in Antarctica must lie in environmental changes in Patagonia. Dust emissions, hence environmental conditions in Patagonia, were very similar during the last two glacials and interglacials, respectively, despite 2-4°C warmer temperatures recorded in Antarctica during the penultimate interglacial than today. 2-3 times higher sea salt fluxes found in both ice cores in the glacial compared to the Holocene are difficult to reconcile with a largely unchanged transport intensity and the distant open ocean source. The substantial glacial enhancements in sea salt aerosol fluxes can be readily explained assuming sea ice formation as the main sea salt aerosol source with a significantly larger expansion of (summer) sea ice in the Weddell Sea than in the Indian Ocean sector. During the penultimate interglacial, our sea salt records point to a 50% reduction of winter sea ice coverage compared to the Holocene both in the Indian and Atlantic Ocean sector of the SO. However, from 20 to 80 ka before present sea salt fluxes show only very subdued millennial changes despite pronounced temperature fluctuations, likely due to the large distance of the sea ice salt source to our drill sites.