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

2017 ◽  
Author(s):  
Pascal Bohleber ◽  
Tobias Erhardt ◽  
Nicole Spaulding ◽  
Helene Hoffmann ◽  
Hubertus Fischer ◽  
...  
Keyword(s):  
Time Series ◽  
Mineral Dust ◽  
Ice Core ◽  
Ice Cores ◽  
Temperature Reconstruction ◽  
Ice Age ◽  
European Alps ◽  
Annual Layer ◽  
Instrumental Temperature

Abstract. Among ice core drilling sites in the European Alps, the Colle Gnifetti (CG) glacier saddle is the only one to offer climate records back to 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. To-date, 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 neighboring ice core, we explore the potential for reconstructing long-term temperature variability from the stable water isotope and mineral dust proxy time series. A high and potentially non-stationary isotope/temperature sensitivity limits the quantitative use of the stable isotope variability thus far. However, we find substantial agreement comparing the mineral dust proxy Ca2+ with instrumental temperature. The temperature-related variability in the Ca2+ record is explained based on the temperature-dependent snow preservation bias combined with the advection of dust-rich air masses coinciding with warm temperatures. We show that using the Ca2+ trends for a quantitative temperature reconstruction results in good agreement with instrumental temperature and the latest summer temperature reconstruction derived from other archives covering the last 1000 years. This includes a Little Ice Age cold period as well as a medieval climate anomaly. In particular, part of the medieval climate period around 1100–1200 AD stands out through an increased occurrence of dust events, potentially resulting from a relative increase in meridional flow and dry conditions over the Mediterranean.

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

2018 ◽  
Vol 14 (1) ◽  
pp. 21-37 ◽  
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.

scholarly journals The Elbrus (Caucasus, Russia) ice core glaciochemistry to reconstruct anthropogenic emissions in central Europe: The case of sulfate

2019 ◽  
Author(s):  
Susanne Preunkert ◽  
Michel Legrand ◽  
Stanislav Kutuzov ◽  
Patrick Ginot ◽  
Vladimir Mikhalenko ◽  
...  
Keyword(s):  
Central Europe ◽  
Ice Core ◽  
Ice Cores ◽  
Fold Increase ◽  
First Century ◽  
Ice Age ◽  
The Caucasus ◽  
Basal Ice ◽  
Common Era

Abstract. This study reports on the glaciochemistry of a deep ice core (182 m long) drilled in 2009 at Mount Elbrus (43°21′ N, 42°26′ E; 5115 m above sea level) in the Caucasus, Russia. Radiocarbon dating of the particulate organic carbon fraction in the ice suggests a basal ice age of ~ 1670 ± 400 cal yr BP. Based on chemical stratigraphy, the upper 168.6 m of the core were dated by counting annual layers. The seasonally resolved chemical records cover the years 1774–2009 (Common Era), thus, being useful to reconstruct many aspects of atmospheric pollution in central Europe from pre-industrial times to present-day. After having examined the extent to which the arrival of large dust plumes originating from Sahara and Middle East modifies the chemical composition of the Elbrus (ELB) snow and ice layers, we focus on the sulfur pollution. The ELB sulfate levels indicate a four- and six-fold increase from 1774–1900 to 1980–1995 in winter and summer, respectively. Remaining close to 116 ± 28 ppb during the nineteen century, the summer sulfate levels started to rise at a mean rate of ~ 6 ppb per year from 1920 to 1950. The summer sulfate increase accelerated between 1950 and 1975 (11 ppb per year), levels reaching a maximum between 1980 and 1990 (730 ± 152 ppb) and subsequently decreasing to 630 ± 130 ppb at the beginning of the twenty first century. Long-term sulfate trends observed in the ELB ice cores are compared with those previously obtained in Alpine ice, the most important difference consists in a more pronounced decrease of the sulfur pollution over the three last decades in western than central Europe.

scholarly journals Radiocarbon dating of glacier ice

2016 ◽  
Author(s):  
Chiara Uglietti ◽  
Alexander Zapf ◽  
Theo M. Jenk ◽  
Sönke Szidat ◽  
Gary Salazar ◽  
...  
Keyword(s):  
Information Needs ◽  
Ice Core ◽  
Ice Cores ◽  
European Alps ◽  
Carbonaceous Aerosols ◽  
14C Dating ◽  
Tropical Regions ◽  
Annual Layer ◽  
Glacier Ice ◽  
Depth Relationship

Abstract. High altitude glaciers and ice caps from mid-latitudes and tropical regions contain valuable signals of past climatic and environmental conditions as well as human activities, but for a meaningful interpretation this information needs to be placed in a precise chronological context. For dating the upper part of ice cores from such sites several relatively precise methods exist, but they fail in the older and deeper part, where plastic deformation of the ice results in strong annual layer thinning and a non-linear age-depth relationship. If sufficient organic matter such as plant, wood or insect fragments were found, radiocarbon (14C) analysis had thus been the only option for a direct and absolute dating of deeper ice core sections. However such fragments are rarely found and even then very likely not at the depths and in the resolution desired. About 10 years ago, a new, complementary dating tool was therefore introduced by our group. It is based on extracting the μg-amounts of the water-insoluble organic carbon (WIOC) fraction of carbonaceous aerosols embedded in the ice matrix for subsequent 14C dating. Meanwhile this new approach was improved considerably, thereby reducing the measurement time and improving the overall precision. Samples with ~ 10 μg WIOC mass can now be dated with reasonable uncertainty of around 10–20 % (variable depending on sample age). This requires about 100 to 500 g of ice considering the WIOC concentrations typically found in mid- and low-latitude glacier ice. Dating polar ice with satisfactory age precision is still not possible since WIOC concentrations are around one order of magnitude lower. The accuracy of the 14C WIOC method was validated by applying it to independently dated ice. With this method the deepest parts of the ice cores from Colle Gnifetti and Mt. Ortles glacier in the European Alps, Illimani glacier in the Bolivian Andes, Tsambagarav ice cap in the Mongolian Altai, and Belukha glacier in the Siberian Altai have been dated. In all cases a strong annual layer thinning towards bedrock was observed and the oldest ages obtained were in the range of 10 000 yrs. 14C WIOC-dating was not only crucial for interpretation of the embedded environmental and climatic histories, but additionally gave a better insight into glacier flow dynamics close to bedrock and past glacier coverage. For this the availability of multiple dating points in the deepest parts was essential, which is the strength of the presented WIOC 14C-dating method, allowing determination of absolute ages from principally every piece of ice.

scholarly journals Secular Trends Of Accumulation Rate On Ice Cores From Dunde Ice Cap, China Over The Last 1000 Years

1990 ◽  
Vol 14 ◽  
pp. 363-363
Author(s):  
Wu Xiaoling ◽  
Li Zhongqin ◽  
Xie Zichu
Keyword(s):  
Accumulation Rate ◽  
Ice Core ◽  
Ice Cores ◽  
Surface Strain ◽  
Entire Length ◽  
Ice Age ◽  
Cooperative Research ◽  
Ice Cap ◽  
Annual Layer ◽  
Lanzhou Institute

Cooperative research programs were conducted on the Dunde Ice Cap (38°06′N, 96°26′E), China, in 1984, 1986, 1987, by the Lanzhou Institute of Glaciology and Geocryology (LIGG), China and the Byrd Polar Research Center (BPRC), U.S.A. This paper gives the preliminary results of the analysis on accumulation rate of the ice cap over the last 1000 years. Three ice cores were recovered to bedrock from the ice-cap summit (5324 m a.s.l.). Core D-1 (139.8 m long) was divided in the field along the entire length and was shared equally between LIGG and BPRC. Core D-2 (136.6 m long) was returned frozen complete to the LIGG for ice-core measurements. In Core D-3 (138.4 m long) the upper sectors were melted and bottled in the field and the lower sectors were returned frozen to the BPRC, U.S.A. Core D-1 was analyzed in China along the entire length for oxygen isotope, liquid conductivity and pH. A year-by-year dating of the ice cores has been made with Dansgaard-Johnsen’s flow pattern by using the data of surface strain-rate (August 1986 to August 1987) and tritium measurements. The resulting time-scales of the ice cores in Dunde Ice Cap yield an age of 4600 yr B.P. The annual layer thicknesses of core D-1 were measured mainly by δ18O analysis and liquid conductivity. The lower δ18O is generally associated with higher electrical conductivity. Annual layer thickness was converted to accumulation rates and compared with meteorological records from Delingxa Meteorological Station. The mean accumulation rate is 518 mm in ice-equivalent. Particular attention is given to the possible impact of the Little Ice Age. Based on spectral analysis of time series for the accumulation variation with depth, short-term (30, 33 year at 0.01 level) and intermediate-term variation (120 year) were discussed. The ice-core research program has been supported by the Chinese National Foundation of Natural Science under Grant DO125-4860011.

scholarly journals Secular Trends Of Accumulation Rate On Ice Cores From Dunde Ice Cap, China Over The Last 1000 Years

1990 ◽  
Vol 14 ◽  
pp. 363
Author(s):  
Wu Xiaoling ◽  
Li Zhongqin ◽  
Xie Zichu
Keyword(s):  
Accumulation Rate ◽  
Ice Core ◽  
Ice Cores ◽  
Surface Strain ◽  
Entire Length ◽  
Ice Age ◽  
Cooperative Research ◽  
Ice Cap ◽  
Annual Layer ◽  
Lanzhou Institute

Cooperative research programs were conducted on the Dunde Ice Cap (38°06′N, 96°26′E), China, in 1984, 1986, 1987, by the Lanzhou Institute of Glaciology and Geocryology (LIGG), China and the Byrd Polar Research Center (BPRC), U.S.A. This paper gives the preliminary results of the analysis on accumulation rate of the ice cap over the last 1000 years. Three ice cores were recovered to bedrock from the ice-cap summit (5324 m a.s.l.). Core D-1 (139.8 m long) was divided in the field along the entire length and was shared equally between LIGG and BPRC. Core D-2 (136.6 m long) was returned frozen complete to the LIGG for ice-core measurements. In Core D-3 (138.4 m long) the upper sectors were melted and bottled in the field and the lower sectors were returned frozen to the BPRC, U.S.A. Core D-1 was analyzed in China along the entire length for oxygen isotope, liquid conductivity and pH. A year-by-year dating of the ice cores has been made with Dansgaard-Johnsen’s flow pattern by using the data of surface strain-rate (August 1986 to August 1987) and tritium measurements. The resulting time-scales of the ice cores in Dunde Ice Cap yield an age of 4600 yr B.P. The annual layer thicknesses of core D-1 were measured mainly by δ18O analysis and liquid conductivity. The lower δ18O is generally associated with higher electrical conductivity. Annual layer thickness was converted to accumulation rates and compared with meteorological records from Delingxa Meteorological Station. The mean accumulation rate is 518 mm in ice-equivalent. Particular attention is given to the possible impact of the Little Ice Age. Based on spectral analysis of time series for the accumulation variation with depth, short-term (30, 33 year at 0.01 level) and intermediate-term variation (120 year) were discussed. The ice-core research program has been supported by the Chinese National Foundation of Natural Science under Grant DO125-4860011.

scholarly journals An 83 000-year-old ice core from Roosevelt Island, Ross Sea, Antarctica

2020 ◽  
Vol 16 (5) ◽  
pp. 1691-1713 ◽  
Author(s):  
James E. Lee ◽  
Edward J. Brook ◽  
Nancy A. N. Bertler ◽  
Christo Buizert ◽  
Troy Baisden ◽  
...  
Keyword(s):  
Ross Sea ◽  
Ice Core ◽  
Ice Cores ◽  
Ice Age ◽  
Age Difference ◽  
Last Deglaciation ◽  
Ice Streams ◽  
West Antarctic Ice Sheet ◽  
Annual Layer ◽  
West Antarctic

Abstract. In 2013 an ice core was recovered from Roosevelt Island, an ice dome between two submarine troughs carved by paleo-ice-streams in the Ross Sea, Antarctica. The ice core is part of the Roosevelt Island Climate Evolution (RICE) project and provides new information about the past configuration of the West Antarctic Ice Sheet (WAIS) and its retreat during the last deglaciation. In this work we present the RICE17 chronology, which establishes the depth–age relationship for the top 754 m of the 763 m core. RICE17 is a composite chronology combining annual layer interpretations for 0–343 m (Winstrup et al., 2019) with new estimates for gas and ice ages based on synchronization of CH4 and δ18Oatm records to corresponding records from the WAIS Divide ice core and by modeling of the gas age–ice age difference. Novel aspects of this work include the following: (1) an automated algorithm for multiproxy stratigraphic synchronization of high-resolution gas records; (2) synchronization using centennial-scale variations in methane for pre-anthropogenic time periods (60–720 m, 1971 CE to 30 ka), a strategy applicable for future ice cores; and (3) the observation of a continuous climate record back to ∼65 ka providing evidence that the Roosevelt Island Ice Dome was a constant feature throughout the last glacial period.

scholarly journals The WAIS-Divide deep ice core WD2014 chronology – Part 2: Methane synchronization (68–31 ka BP) and the gas age-ice age difference

2014 ◽  
Vol 10 (4) ◽  
pp. 3537-3584 ◽  
Author(s):  
C. Buizert ◽  
K. M. Cuffey ◽  
J. P. Severinghaus ◽  
D. Baggenstos ◽  
T. J. Fudge ◽  
...  
Keyword(s):  
Ice Core ◽  
Impurity Content ◽  
Ice Cores ◽  
Ice Age ◽  
Age Difference ◽  
Atmospheric Methane ◽  
High Accumulation ◽  
West Antarctic Ice Sheet ◽  
Annual Layer ◽  
West Antarctic

Abstract. The West Antarctic Ice Sheet (WAIS)-Divide ice core (WAIS-D) is a newly drilled, high-accumulation deep ice core that provides Antarctic climate records of the past ∼68 ka at unprecedented temporal resolution. The upper 2850 m (back to 31.2 ka BP) have been dated using annual-layer counting. Here we present a chronology for the deep part of the core (67.8–31.2 ka BP), which is based on stratigraphic matching to annual-layer-counted Greenland ice cores using globally well-mixed atmospheric methane. We calculate the WAIS-D gas age-ice age difference (Δage) using a combination of firn densification modeling, ice flow modeling, and a dataset of δ15N-N2, a proxy for past firn column thickness. The largest Δage at WAIS-D occurs during the last glacial maximum, and is 525 ± 100 years. Internally consistent solutions can only be found when assuming little-to-no influence of impurity content on densification rates, contrary to a recently proposed hypothesis. We synchronize the WAIS-D chronology to a linearly scaled version of the layer-counted Greenland Ice Core Chronology (GICC05), which brings the age of Dansgaard-Oeschger (DO) events into agreement with the U/Th absolutely dated Hulu speleothem record. The small Δage at WAIS-D provides valuable opportunities to investigate the timing of atmospheric greenhouse gas variations relative to Antarctic climate, as well as the interhemispheric phasing of the bipolar "seesaw".

scholarly journals Spatial representativity of air-temperature information from instrumental and ice-core-based isotope records in the European Alps

2002 ◽  
Vol 35 ◽  
pp. 157-161 ◽  
Author(s):  
Wolfgang Schöner ◽  
Ingeborg Auer ◽  
Reinhard Böhm ◽  
Lothar Keck ◽  
Dietmar Wagenbach
Keyword(s):  
Air Temperature ◽  
Ice Core ◽  
Ice Cores ◽  
Summer Precipitation ◽  
High Elevation ◽  
Summer Temperature ◽  
Temperature Variability ◽  
Temperature Record ◽  
European Alps

AbstractSpatial correlations between Alpine high-elevation and European low-elevation instrumental air temperatures are computed to assess the spatial representativity of a high-Alpine ice-core isotope proxy temperature record. the correlation analyses indicate that air-temperature records at Alpine ice-core drill sites are representative for central Europe, particularly in summer. While Alpine ice cores generally show a large scattering in the conserved section of the year, long-term records from low-accumulation sites consist almost solely of summer precipitation and thus reflect isotope proxy summer-temperature variability. However, correlation between seasonal and annual instrumental air temperature indicates that summer temperature variability provides an adequate approach to annual temperature variability. Comparison of long-term ice-core δ18O records from Colle Gnifetti (4450ma.s.l.), Monte Rosa, Western Alps, with local instrumental summer temperatures inferred from an instrumental network shows good agreement in the long-term scale. Thus Alpine long-term ice-core δ18O records are representative for central European air-temperature variability.

scholarly journals An 83 000 year old ice core from Roosevelt Island, Ross Sea, Antarctica

2018 ◽  
Author(s):  
James E. Lee ◽  
Edward J. Brook ◽  
Nancy A. N. Bertler ◽  
Christo Buizert ◽  
Troy Baisden ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Ross Sea ◽  
Molecular Nitrogen ◽  
Ice Core ◽  
Ice Cores ◽  
Ice Age ◽  
Ice Streams ◽  
West Antarctic Ice Sheet ◽  
Annual Layer ◽  
West Antarctic

Abstract. In 2013, an ice core was recovered from Roosevelt Island in the Ross Sea, Antarctica, as part of the Roosevelt Island Climate Evolution (RICE) project. Roosevelt Island is located between two submarine troughs carved by paleo-ice-streams. The RICE ice core provides new important information about the past configuration of the West Antarctic Ice Sheet and its retreat during the most recent deglaciation. In this work, we present the RICE17 chronology and discuss preliminary observations from the new records of methane, the isotopic composition of atmospheric molecular oxygen (δ18O-Oatm), the isotopic composition of atmospheric molecular nitrogen (δ15N-N2) and total air content (TAC). RICE17 is a composite chronology combining annual layer interpretations, gas synchronization, and firn modeling strategies in different sections of the core. An automated matching algorithm is developed for synchronizing the high-resolution section of the RICE gas records (60–720 m, 1971 CE to 30 ka) to corresponding records from the WAIS Divide ice core, while deeper sections are manually matched. Ice age for the top 343 m (2635 yr BP, before 1950 C.E.) is derived from annual layer interpretations and described in the accompanying paper by Winstrup et al. (2017). For deeper sections, the RICE17 ice age scale is based on the gas age constraints and the ice age-gas age offset estimated by a firn densification model. Novel aspects of this work include: 1) stratigraphic matching of centennial-scale variations in methane for pre-anthropogenic time periods, a strategy which will be applicable for developing precise chronologies for future ice cores, 2) the observation of centennial-scale variability in methane throughout the Holocene which suggests that similar variations during the late preindustrial period need not be anthropogenic, and 3) the observation of continuous climate records dating back to ∼ 65 ka which provide evidence that the Roosevelt Island Ice Dome was a constant feature throughout the last glacial period.

Alpine Ice Cores as Climate and Environmental Archives

2019 ◽  
Author(s):  
Pascal Bohleber
Keyword(s):  
Ice Core ◽  
Ice Cores ◽  
Climate Science ◽  
Snow Accumulation ◽  
Great Success ◽  
European Alps ◽  
Mountain Areas ◽  
High Accumulation ◽  
Geophysical Surveys

The European Alps feature a unique situation with the densest network of long-term instrumental climate observations and anthropogenic emission sources located in the immediate vicinity of glaciers suitable for ice core studies. To archive atmospheric changes in an undisturbed sequence of firn and ice layers, ice core drilling sites require temperatures low enough to minimize meltwater percolation. In the Alps, this implies a restriction to the highest summit glaciers of comparatively small horizontal and vertical extension (i.e., with typical ice thickness not much exceeding 100 m). As a result, Alpine ice cores offer either high-resolution or long-term records, depending on the net snow accumulation regime of the drilling site. High-accumulation Alpine ice cores have been used with great success to study the anthropogenic influence on aerosol-related atmospheric impurities over the last 100 years or so. However, respective long-term reconstructions (i.e., substantially exceeding the instrumental era) from low-accumulation sites remain comparatively sparse. Accordingly, deciphering Alpine ice cores as long-term climate records deserves special emphasis. Certain conditions must exist for Alpine ice cores to serve as climate archives, and this is important in particular regarding the challenges and achievements that have significance for ice cores from other mountain areas: (a) a reliable chronology is the fundamental prerequisite for interpreting any ice core proxy time series. Advances in radiometric ice dating and annual layer counting offer the tools to crucially increase dating precision in the preinstrumental era. (b) Glacier flow effects and spatio-seasonal snow deposition variability challenge linking the ice core proxy signals to the respective atmospheric variability (e.g., of temperature, mineral dust, and impurity concentrations). Here, assistance comes from combining multiple ice cores from one site and from complementary meteorological, glaciological, and geophysical surveys. (c) As Alpine ice cores continue to advance their contribution to Holocene climate science, exploring the link to instrumental, historical, and other natural climate archives gains increasing importance.

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