scholarly journals Investigating cold based summit glaciers through direct access to the glacier base: a case study constraining the maximum age of Chli Titlis glacier, Switzerland

2018 ◽  
Vol 12 (1) ◽  
pp. 401-412 ◽  
Author(s):  
Pascal Bohleber ◽  
Helene Hoffmann ◽  
Johanna Kerch ◽  
Leo Sold ◽  
Andrea Fischer
Keyword(s):  
Ice Core ◽  
Ice Cores ◽  
Eastern Alps ◽  
Systematic Investigation ◽  
Direct Access ◽  
European Alps ◽  
Central Switzerland ◽  
Ice Conditions ◽  
The Alps

Abstract. Cold glaciers at the highest locations of the European Alps have been investigated by drilling ice cores to retrieve their stratigraphic climate records. Findings like the Oetztal ice man have demonstrated that small ice bodies at summit locations of comparatively lower altitudes may also contain old ice if locally frozen to the underlying bedrock. In this case, constraining the maximum age of their lowermost ice part may help to identify past periods with minimum ice extent in the Alps. However, with recent warming and consequent glacier mass loss, these sites may not preserve their unique climate information for much longer. Here we utilized an existing ice cave at Chli Titlis (3030 m), central Switzerland, to perform a case study for investigating the maximum age of cold-based summit glaciers in the Alps. The cave offers direct access to the glacier stratigraphy without the logistical effort required in ice core drilling. In addition, a pioneering exploration had already demonstrated stagnant cold ice conditions at Chli Titlis, albeit more than 25 years ago. Our englacial temperature measurements and the analysis of the isotopic and physical properties of ice blocks sampled at three locations within the ice cave show that cold ice still exists fairly unchanged today. State-of-the-art micro-radiocarbon analysis constrains the maximum age of the ice at Chli Titlis to about 5000 years before present. By this means, the approach presented here will contribute to a future systematic investigation of cold-based summit glaciers, also in the Eastern Alps.

scholarly journals Investigating cold based summit glaciers through direct access to basal ice: A case study constraining the maximum age of Chli Titlis glacier, Switzerland

2017 ◽  
pp. 1-15
Author(s):  
Pascal Bohleber ◽  
Helene Hoffmann ◽  
Johanna Kerch ◽  
Leo Sold ◽  
Andrea Fischer
Keyword(s):  
Ice Cores ◽  
Eastern Alps ◽  
Systematic Investigation ◽  
Direct Access ◽  
Glacier Mass Balance ◽  
Great Success ◽  
European Alps ◽  
Basal Ice ◽  
Central Switzerland ◽  
Ice Conditions

Cold glaciers at the highest locations of the European Alps have been investigated with great success by drilling ice cores to retrieve their stratigraphic climate records. Findings like the Oetztal ice man have demonstrated that small ice bodies at summit locations of comparatively lower altitudes may also contain old ice if comprising ice frozen to the underlying bedrock. In this case, constraining the maximum age of their basal ice part may help to identify past periods with minimum ice extent in the Alps. Facing ongoing warming and recent years with extremely negative glacier mass balance, these sites may not preserve their unique climate information for much longer, however. Since sampling and dating the lowermost ice is essential, and usually requires substantial logistical (drilling) effort, we utilize here the direct access to basal ice offered by an existing ice cave at Chli Titlis (3030 m), Central Switzerland. Our dedicated approach comprises a combination of standard glaciological tools with the analysis of the isotopic and physical properties and sophisticated radiocarbon dating techniques. By this means we demonstrate that, in comparison to an earlier study at Chli Titlis, stagnant cold basal ice conditions still exist fairly unchanged more than 25 years after the pioneering exploration. Our radiocarbon analysis constrains the maximum age of the ice at Chli Titlis to about 5000 years before present. By this means, the approach presented here will contribute to a future systematic investigation of cold-based summit glaciers also targeting the Eastern Alps.

Estimating the diffusion length in the deepest section of ice cores; A case study for MIS19 in Dome-C

2021 ◽  
Author(s):  
Thomas Laepple ◽  
Thomas Münch ◽  
Torben Kunz ◽  
Mathieu Casado ◽  
Maria Hoerhold
Keyword(s):  
Diffusion Length ◽  
Ice Core ◽  
Ice Cores ◽  
Climate Information ◽  
Climate Signal ◽  
A Value ◽  
Recovery Strategies ◽  
Length Estimate ◽  
And Diffusion

<p>To recover very old climate information from ice core records, one needs to interpret the deepest part of an ice core. As the oldest record, the Dome-C ice core can serve as an analogue for the Beyond EPICA Oldest Ice Core that is currently being drilled.<br><br>Pol et al., EPSL 2010 analyzed high resolution water isotope data from the Dome-C ice core and found evidence for a limited preservation of climate variability in the deep section of the core due to mixing and diffusion. For instance, for Marine Isotope Stage 19, the study estimated a mixing/diffusion length between 40 and 60 cm, a value more than double than what is predicted by current firn and ice diffusion models. Knowing the diffusion length is important to interpret the isotope signal and is the basis to deconvolve climate records. As a result, it is key to bridge the gap in the estimation of the diffusion length between potentially biased statistical methods and firn and ice diffusion models.<br>We review this diffusion length estimate for MIS19, and also outline a new general method how to estimate the diffusion length in highly thinned deep ice.  This approach presents an important tool for better characterizing the preservation of the climate signal in old ice and thus for designing optimal sampling and recovery strategies.</p><p> </p>

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 Mapping the suitability for ice-core drilling of glaciers in the European Alps and the Asian High Mountains

2017 ◽  
Vol 64 (243) ◽  
pp. 12-26 ◽  
Author(s):  
ROBERTO GARZONIO ◽  
BIAGIO DI MAURO ◽  
DANIELE STRIGARO ◽  
MICOL ROSSINI ◽  
ROBERTO COLOMBO ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Ice Core ◽  
Ice Cores ◽  
Weight Of Evidence ◽  
European Alps ◽  
High Mountains ◽  
Mountain Glacier ◽  
Past Climate ◽  
Core Drilling ◽  
Mountain Glaciers

ABSTRACTIce cores from mid-latitude mountain glaciers provide detailed information on past climate conditions and regional environmental changes, which is essential for placing current climate change into a longer term perspective. In this context, it is important to define guidelines and create dedicated maps to identify suitable areas for future ice-core drillings. In this study, the suitability for ice-core drilling (SICD) of a mountain glacier is defined as the possibility of extracting an ice core with preserved stratigraphy suitable for reconstructing past climate. Morphometric and climatic variables related to SICD are selected through literature review and characterization of previously drilled sites. A quantitative Weight of Evidence method is proposed to combine selected variables (i.e. slope, local relief, temperature and direct solar radiation) to map the potential drilling sites in mid-latitude mountain glaciers. The method was first developed in the European Alps and then applied to the Asian High Mountains. Model performances and limitations are discussed and first indications of new potential drilling sites in the Asian High Mountains are provided. Results presented here can facilitate the selection of future drilling sites especially on unexplored Asian mountain glaciers towards the understanding of climate and environmental changes.

scholarly journals Glaciation's topographic control on Holocene erosion at the eastern edge of the Alps

2016 ◽  
Vol 4 (4) ◽  
pp. 895-909 ◽  
Author(s):  
Jean L. Dixon ◽  
Friedhelm von Blanckenburg ◽  
Kurt Stüwe ◽  
Marcus Christl
Keyword(s):  
Eastern Alps ◽  
European Alps ◽  
Glacial Erosion ◽  
Erosion Rates ◽  
The Alps ◽  
Glacial Processes ◽  
Cosmogenic 10Be ◽  
Topographic Forcing ◽  
Eastern Edge

Abstract. What is the influence of glacial processes in driving erosion and uplift across the European Alps? It has largely been argued that repeated erosion and glaciation sustain isostatic uplift and topography in a decaying orogen. But some parts of the Alps may still be actively uplifting via deep lithospheric processes. We add insight to this debate by isolating the role of post-glacial topographic forcing on erosion rates. To do this, we quantify the topographic signature of past glaciation on millennial-scale erosion rates in previously glaciated and unglaciated catchments at the easternmost edge of the Austrian Alps. Newly measured catchment-wide erosion rates, determined from cosmogenic 10Be in river-borne quartz, correlate with basin relief and mean slope. GIS-derived slope–elevation and slope–area distributions across catchments provide clear topographic indicators of the degree of glacial preconditioning, which further correlates with erosion rates. Erosion rates in the easternmost, non-glaciated basins range from 40 to 150 mm ky−1 and likely reflect underlying tectonic forcings in this region, which have previously been attributed to recent (post 5 Ma) uplift. By contrast, erosion rates in previously glaciated catchments range from 170 to 240 mm ky−1 and reflect the erosional response to local topographic preconditioning by repeated glaciations. Together, these data suggest that Holocene erosion across the Eastern Alps is strongly shaped by the local topography relict from previous glaciations. Broader, landscape-wide forcings, such as the widely debated deep mantle-driven or isostatically driven uplift, result in lesser controls on both topography and erosion rates in this region. Comparing our data to previously published erosion rates across the Alps, we show that post-glacial erosion rates vary across more than 2 orders of magnitude. This high variation in post-glacial erosion may reflect combined effects of direct tectonic and modern climatic forcings but is strongly overprinted by past glacial climate and its topographic legacy.

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 Glaciation's topographic control on Holocene erosion at the eastern edge of the Alps

2016 ◽  
Author(s):  
Jean L. Dixon ◽  
Friedhelm von Blanckenburg ◽  
Kurt Stüwe ◽  
Marcus Cristl
Keyword(s):  
Eastern Alps ◽  
European Alps ◽  
Glacial Erosion ◽  
Erosion Rates ◽  
The Alps ◽  
Glacial Processes ◽  
Cosmogenic 10Be ◽  
Topographic Forcing ◽  
Eastern Edge

Abstract. What is the influence of glacial processes in driving erosion and uplift across the European Alps? It has largely been argued that repeated erosion through glaciation sustains isostatic uplift and topography in a decaying orogen. But, some insist that the Alps are an orogen still actively uplifting (e.g., Hergarten et al., 2010). We add insight to this debate by isolating the role of post-glacial topographic forcing on erosion rates. To do this, we quantify the topographic signature of past glaciation on millennial scale erosion rates in previously glaciated and unglaciated catchments at the easternmost edge of the Austrian Alps. Newly measured catchment-wide erosion rates, determined from cosmogenic 10Be in river-borne quartz, correlate with basin relief and mean slope. GIS-derived slope-elevation and slope-area distributions across catchments provide clear topographic indicators of the degree of glacial preconditioning, which further correlates with erosion rates. Erosion rates in the eastern-most, non-glaciated basins range from 40 to 150 mm/ky and likely reflect underlying tectonic forcings in this region, which have previously been attributed to recent (post 5 Ma) uplift (Legrain et al., 2015). By contrast, erosion rates in previously glaciated catchments range from 170 to 240 mm/ky and reflect the erosional response to local topographic preconditioning by repeated glaciations. Together, these data suggest that Holocene erosion across the Eastern Alps is strongly shaped by the local topography relict from previous glaciations. Broader, landscape-wide forcings, such as the widely debated deep mantle-driven or isostatically-driven uplift, result in lesser controls on both topography and erosion rates in this region. Comparing our data to previously published erosion rates across the Alps, we show that post-glacial erosion rates vary across more than two orders of magnitude with poor topographic indicators of controls. This high variation in post-glacial erosion may reflect combined effects of direct tectonic and modern climatic forcings, but is strongly overprinted by past glacial climate and its topographic legacy.

scholarly journals Impact of Source Region on the δ18O Signal in Snow: A Case Study from Mount Wrangell, Alaska

2015 ◽  
Vol 17 (1) ◽  
pp. 139-151 ◽  
Author(s):  
G. W. K. Moore ◽  
Robert D. Field ◽  
Carl S. Benson
Keyword(s):  
Source Region ◽  
Ice Core ◽  
Empirical Relationship ◽  
Ice Cores ◽  
Local Temperature ◽  
Underlying Assumption ◽  
South Central ◽  
Stable Isotopic ◽  
Snowfall Event

Abstract The stable isotopic composition of water in ice cores is an important source of information on past climate variability. At its simplest level, the underlying assumption is that there is an empirical relationship between the normalized difference in the concentration for these stable isotopes and a specified local temperature at the ice core site. There are, however, nonlocal processes, such as a change in source region or a change in the atmospheric pathway, which can impact the stable isotope signal, thereby complicating its use as a proxy for temperature. In this paper, the importance of these nonlocal processes are investigated through the analysis of the synoptic-scale circulation during a snowfall event at the summit of Mount Wrangell (62°N, 144°W; 4300 m MSL) in south-central Alaska. During this event there was, over a 1-day period in which the local temperature was approximately constant, a change in δ18O that exceeded half that normally seen to occur in the region between summer and winter. As shall be shown, this arose from a change in the source region, from the subtropical eastern Pacific to northeastern Asia, for the snow that fell on Mount Wrangell during the event.

scholarly journals A <i>synthetic</i> ice core approach to estimate ion relocation in an ice field site experiencing periodical melt; a case study on Lomonosovfonna, Svalbard

2015 ◽  
Vol 9 (5) ◽  
pp. 5053-5095
Author(s):  
C. P. Vega ◽  
V. A. Pohjola ◽  
E. Beaudon ◽  
B. Claremar ◽  
W. J. J. van Pelt ◽  
...  
Keyword(s):  
Ice Core ◽  
Chemical Properties ◽  
Ice Cores ◽  
Field Site ◽  
Ice Field ◽  
Physical Stratigraphy ◽  
Physical And Chemical ◽  
Annual Resolution ◽  
And Chemical Properties

Abstract. Physical and chemical properties of four different ice cores (LF-97, LF-08, LF-09 and LF-11) drilled at Lomonosovfonna, Svalbard, were compared to investigate the effects of meltwater percolation on the chemical and physical stratigraphy of these records. A synthetic ice core approach was employed as reference record to estimate the ionic relocation and meltwater percolation length at this site during the period 2007–2010. Using this method, the ion elution sequence obtained for Lomonosovfonna was SO42- > NO3- > NH4+ > Mg2+ > Cl-, K+ > Na+ > Ca2+, with acidic ions being the most mobile within the snowpack. The relocation length of most of the ions was in the order of 1 m, with the exception of SO42- showing relocation lengths > 2 m during this period. In addition, by using both a positive degree day (PDD) and a snow-energy model approaches to estimate the percentage of melt at Lomonosovfonna, we have calculated a melt percentage (MP) of the total annual accumulation within the range between 48 and 70 %, for the period between 2007 and 2010 which is above the MP range suggested by the ion relocation evidenced in the LF-syn core (i.e. MP = 30 %). Using a firn-densification model to constrain the melt range, a MP of 30 % was found over the same period which is consistent with the results of the synthetic ice core approach, and a 45 % of melt for the last 60 years. Considering the ionic relocation lengths and annual melt percentages, we estimate that the atmospheric ionic signal remains preserved in recently drilled Lomonosovfonna ice cores at an annual or bi-annual resolution.

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.

Sign in / Sign up

Export Citation Format

Share Document