Ground and Dead Ice in Alpine Proglacial Areas – Sensitivity towards Climate Change since 1850, Recent Dynamics and Future Trends

2020 ◽  
Author(s):  
Heidi Bernsteiner ◽  
Joachim Götz ◽  
Florian Haas ◽  
Tobias Heckmann ◽  
Oliver Sass ◽  
...  
Keyword(s):  
Climate Change ◽  
Isotope Analysis ◽  
Ground Surface ◽  
Transient State ◽  
Research Unit ◽  
Ice Age ◽  
European Alps ◽  
Future Trends ◽  
Atmospheric Conditions ◽  
Recent Climate

<p>As the climate warms, the earths’ cryosphere melts. Among the regions with the highest sensitivity to recent climate change are the high altitudes of the European Alps. This can be seen most clearly in the melting of glacier ice. Most glaciers show a strong receding trend since the last maximum extent during the little ice age (LIA) around AD 1850. When glaciers retreat, they leave behind a characteristic paraglacial landscape in a transient state from glacial to non-glacial conditions. Dominated by large amounts of unconsolidated glacial sediments they show an extremely high geomorphic activity.</p><p>However, these proglacial areas can still hold ice even decades after the glacier has left. In a simplified manner, this can be conceptually described by two main mechanisms: i) When glaciers retreat parts of the glacier front are often decoupled from the main glacier. These so-called dead ice bodies can remain for years, especially when they are buried by a thick debris cover and thus protected from atmospheric conditions. ii) Particularly in high-elevated glacier forefields, the thermal regime can be suitable for the direct transition from a glacial to a periglacial environment, compassing the aggradation of permafrost ice in areas that have been released from the glacier.</p><p>Climate warming speeds up in recent times, related with an enhanced receding of glaciers and growing alpine proglacial areas. Ground and dead ice are among the most important drivers of geomorphic activity in these regions, though in the long-term it is most likely, that it will melt out as well. How fast this will happen and in what stage it may play a role in stabilizing these environments is not yet fully clarified. Therefore, a better knowledge on ice distribution and dynamics in alpine proglacial regions is needed. Additionally, the quantification of ice and water contents is crucial in terms of potential hazardous processes, regarding the supply of (drinking) water and hydropower.</p><p>Here we present a new (PhD-) project in close cooperation with the DFG-funded research unit SEHAG, which is at the beginning of its implementation. Focussing on ground and dead ice we aim i) to assess the current distribution, ii) to reconstruct dynamics since the LIA, iii) to reveal recent and future trends (aggradation, degradation and persistence), and iv) to quantify effects on sediment dynamics in three Central Alpine proglacial areas. We combine different geophysical techniques with a focus on electrical resistivity tomography, water isotope analysis and ground (surface) temperature measurements with high-resolution geomorphic change modelling.</p>

scholarly journals Past climate changes and permafrost depth at the Lake El'gygytgyn site: implications from data and thermal modeling

2013 ◽  
Vol 9 (1) ◽  
pp. 119-133 ◽  
Author(s):  
D. Mottaghy ◽  
G. Schwamborn ◽  
V. Rath
Keyword(s):  
Surface Temperature ◽  
Thermal Regime ◽  
Climate Changes ◽  
Ground Surface ◽  
Temperature Data ◽  
Ice Age ◽  
Drilling Process ◽  
Past Climate ◽  
Ground Surface Temperature ◽  
Recent Climate

Abstract. This study focuses on the temperature field observed in boreholes drilled as part of interdisciplinary scientific campaign targeting the El'gygytgyn Crater Lake in NE Russia. Temperature data are available from two sites: the lake borehole 5011-1 located near the center of the lake reaching 400 m depth, and the land borehole 5011-3 at the rim of the lake, with a depth of 140 m. Constraints on permafrost depth and past climate changes are derived from numerical simulation of the thermal regime associated with the lake-related talik structure. The thermal properties of the subsurface needed for these simulations are based on laboratory measurements of representative cores from the quaternary sediments and the underlying impact-affected rock, complemented by further information from geophysical logs and data from published literature. The temperature observations in the lake borehole 5011-1 are dominated by thermal perturbations related to the drilling process, and thus only give reliable values for the lowermost value in the borehole. Undisturbed temperature data recorded over more than two years are available in the 140 m deep land-based borehole 5011-3. The analysis of these observations allows determination of not only the recent mean annual ground surface temperature, but also the ground surface temperature history, though with large uncertainties. Although the depth of this borehole is by far too insufficient for a complete reconstruction of past temperatures back to the Last Glacial Maximum, it still affects the thermal regime, and thus permafrost depth. This effect is constrained by numerical modeling: assuming that the lake borehole observations are hardly influenced by the past changes in surface air temperature, an estimate of steady-state conditions is possible, leading to a meaningful value of 14 ± 5 K for the post-glacial warming. The strong curvature of the temperature data in shallower depths around 60 m can be explained by a comparatively large amplitude of the Little Ice Age (up to 4 K), with low temperatures prevailing far into the 20th century. Other mechanisms, like varying porosity, may also have an influence on the temperature profile, however, our modeling studies imply a major contribution from recent climate changes.

scholarly journals Current glacier recession causes significant rockfall increase: The immediate paraglacial response of deglaciating cirque walls

2020 ◽  
Author(s):  
Ingo Hartmeyer ◽  
Robert Delleske ◽  
Markus Keuschnig ◽  
Michael Krautblatter ◽  
Andreas Lang ◽  
...  
Keyword(s):  
Minor Effect ◽  
European Alps ◽  
Atmospheric Conditions ◽  
Glacier Surface ◽  
Terrestrial Lidar ◽  
Physical Weathering ◽  
Ice Surface ◽  
Recent Climate ◽  
Ample Supply ◽  
A Minor

Abstract. In the European Alps almost half the glacier volume disappeared over the past 150 years. The loss is reflected in glacier retreat and ice surface lowering even at high altitude. In steep glacial cirques surface lowering exposes rock to atmospheric conditions for the very first time in many millennia. Instability of rockwalls has long been identified as one of the direct consequences of deglaciation, but so far cirque-wide quantification of rockfall at high-resolution is missing. Based on terrestrial LiDAR a rockfall inventory for the permafrost-affected rockwalls of two rapidly deglaciating cirques in the Central Alps of Austria (Kitzsteinhorn) is established. Over six-years (2011–2017) 78 rockwall scans were acquired to generate data of high spatial and temporal resolution. 632 rockfalls were registered ranging from 0.003 to 879.4 m³, mainly originating from pre-existing structural rock weaknesses. 60 % of the rockfall volume detached from less than ten vertical meters above the glacier surface, indicating enhanced rockfall activity over tens of years following deglaciation. Debuttressing seems to play a minor effect only. Rather, preconditioning is assumed to start inside the Randkluft (gap between cirque wall and glacier) where sustained freezing and ample supply of liquid water likely cause enhanced physical weathering and high plucking stresses. Following deglaciation, pronounced thermomechanical strain is induced and an active layer penetrates into the formerly perennially frozen bedrock. These factors likely cause the observed paraglacial rockfall increase close to the glacier surface. This paper presents the most extensive dataset of high-alpine rockfall to date and the first systematic documentation of a cirque-wide erosion response of glaciated rockwalls to recent climate warming.

scholarly journals Climate change and the global pattern of moraine-dammed glacial lake outburst floods

2017 ◽  
Author(s):  
Stephan Harrison ◽  
Jeffrey S. Kargel ◽  
Christian Huggel ◽  
John Reynolds ◽  
Dan H. Shugar ◽  
...  
Keyword(s):  
Climate Change ◽  
Ice Age ◽  
Dam Failure ◽  
Glacial Lake ◽  
Glacier Recession ◽  
Outburst Floods ◽  
Glacial Lake Outburst Floods ◽  
Lake Formation ◽  
Recent Climate ◽  
Moraine Dam Failure

Abstract. Despite recent research identifying a clear anthropogenic impact on glacier recession, the effect of recent climate change on glacier-related hazards is at present unclear. Here we present the first global spatio-temporal assessment of glacial lake outburst floods (GLOFs) focusing explicitly on lake drainage following moraine dam failure. These floods occur as mountain glaciers recede and downwaste and many have an enormous impact on downstream communities and infrastructure. Our assessment of GLOFs associated with the collapse of moraine-dammed lakes provides insights into the historical trends of GLOFs and their distributions under current and future global climate change. We observe a clear global increase in GLOF frequency and their regularity around 1930, which likely represents a lagged response to post-Little Ice Age warming. Notably, we also show that GLOF frequency and their regularity – rather unexpectedly – has declined in recent decades even during a time of rapid glacier recession. Although previous studies have suggested that GLOFs will increase in response to climate warming and glacier recession, our global results demonstrate that this has not yet clearly happened. From assessment of the timing of climate forcing, lag times in glacier recession, lake formation and moraine dam failure, we predict increased GLOF frequencies during the next decades and into the 22nd century.

scholarly journals Early Holocene cold snaps and their expression in the moraine record of the Eastern European Alps

2021 ◽  
Author(s):  
Sandra M. Braumann ◽  
Joerg M. Schaefer ◽  
Stephanie M. Neuhuber ◽  
Christopher Lüthgens ◽  
Alan J. Hidy ◽  
...  
Keyword(s):  
Climate Change ◽  
Arctic Region ◽  
Climate System ◽  
Early Holocene ◽  
Ice Age ◽  
The Arctic ◽  
European Alps ◽  
Eastern European ◽  
Exposure Dating ◽  
The Past

Abstract. Glaciers preserve climate variations in their geological and geomorphological records, which makes them prime candidates for climate reconstructions. Investigating the glacier-climate system over the past millennia is particularly relevant because, first, the amplitude and frequency of natural climate variability during the Holocene provides the climatic context against which modern, human-induced climate change must be assessed. Second, the transition from the last glacial to the current interglacial promises important insights into the climate system during warming, which is of particular interest with respect to ongoing climate change. Evidence of stable ice margin positions that record cooling during the past 12 ka are preserved in two glaciated valleys of the Silvretta Massif in the Eastern European Alps, the Jamtal (JAM) and the Laraintal (LAR). We mapped and dated moraines in these catchments including historical ridges using Beryllium-10 Surface Exposure Dating (10Be SED) techniques, and correlate resulting moraine formation intervals with climate proxy records to evaluate the spatial and temporal scale of these cold phases. The new geochronologies indicate two moraine formation intervals (MFI) during the Early Holocene (EH): 10.8 ± 0.7 ka (n = 9) and 11.2 ± 0.8 ka (n = 12). Boulder ages along historical moraines (n = 6) imply at least two glacier advances during the Little Ice Age (LIA; c. 1250–1850 CE), around 1300 CE and in the second half of the 18th century. An earlier advance to the same position may have occurred around 500 CE. The Jamtal and Laraintal moraine chronologies provide evidence that millennial scale EH warming was superimposed by centennial scale cooling. The timing of EH moraine formation is contemporaneous with brief temperature drops identified in local and regional paleoproxy records, most prominently with the Preboreal Oscillation (PBO), and is consistent with moraine deposition in other catchments in the European Alps, and in the Arctic region. This consistency points to cooling beyond the local scale and therefore a regional or even hemispheric climate driver. Freshwater input sourced from the Laurentide Ice Sheet (LIS), which changed circulation patterns in the North Atlantic, is a plausible explanation for EH cooling and moraine formation in the Nordic region and in Europe.

scholarly journals Application of inventory data for estimating characteristics of and regional climate-change effects on mountain glaciers: a pilot study with the European Alps

1995 ◽  
Vol 21 ◽  
pp. 206-212 ◽  
Author(s):  
Wilfried Haeberli ◽  
Martin Hoelzle
Keyword(s):  
Climate Change ◽  
Pilot Study ◽  
Mass Balance ◽  
Regional Climate ◽  
Ice Age ◽  
European Alps ◽  
Inventory Data ◽  
Mountain Glaciers ◽  
Climate Change Effects ◽  
Length Changes

A parameterization scheme using simple algorithms for unmeasured glaciers is being applied to glacier inventory data to estimate the basic glaciological characteristics of the inventoried ice bodies and simulate potential climate-change effects on mountain glaciers. For past and potential climate scenarios, glacier changes for assumed mass-balance changes are calculated as step functions between steady-state conditions for time intervals that approximately correspond to the characteristic dynamic response time (a few decades) of the glaciers. In order to test the procedure, a pilot study was carried out in the European Alps where detailed glacier inventories had been compiled around the mid-1970s. Total glacier volume in the Alps is estimated at about 130 km3 for the mid-1970s; strongly negative mass balances are likely to have caused a loss of about 10–20% of this total volume during the decade 1980–90. Backward calculation of glacier-length changes using a mean annual mass balance of 0.25m w.e.a−1 since the end of the “Little Ice Age” around 1850 AD gives considerable scatter but satisfactory overall results as compared with long-term observations. The total loss of Alpine surface ice mass since 1850 can be estimated at about half the original value. An acceleration of this development, with annual mass losses of around 1 m a−1 or more as anticipated from IPCC scenario A for the coming century, could eliminate major parts of the presently existing Alpine ice volume within decades.

scholarly journals Current glacier recession causes significant rockfall increase: the immediate paraglacial response of deglaciating cirque walls

2020 ◽  
Vol 8 (3) ◽  
pp. 729-751 ◽  
Author(s):  
Ingo Hartmeyer ◽  
Robert Delleske ◽  
Markus Keuschnig ◽  
Michael Krautblatter ◽  
Andreas Lang ◽  
...  
Keyword(s):  
Minor Effect ◽  
European Alps ◽  
Atmospheric Conditions ◽  
Glacier Surface ◽  
Terrestrial Lidar ◽  
Physical Weathering ◽  
Ice Surface ◽  
Recent Climate ◽  
Ample Supply ◽  
A Minor

Abstract. In the European Alps, almost half the glacier volume has disappeared over the past 150 years. The loss is reflected in glacier retreat and ice surface lowering even at high altitude. In steep glacial cirques, surface lowering exposes rock to atmospheric conditions probably for the very first time in several millennia. Instability of rockwalls has long been identified as one of the direct consequences of deglaciation, but so far cirque-wide quantification of rockfall at high resolution is missing. Based on terrestrial lidar, a rockfall inventory for the permafrost-affected rockwalls of two rapidly deglaciating cirques in the Central Alps of Austria (Kitzsteinhorn) is established. Over 6 years (2011–2017), 78 rockwall scans were acquired to generate data of high spatial and temporal resolution. Overall, 632 rockfalls were registered, ranging from 0.003 to 879.4 m3, mainly originating from pre-existing structural rock weaknesses. A total of 60 % of the rockfall volume detached from less than 10 vertical metres above the glacier surface, indicating enhanced rockfall activity over tens of years following deglaciation. Debuttressing seems to play a minor effect only. Rather, preconditioning is assumed to start inside the randkluft (void between cirque wall and glacier) where measured sustained freezing and ample supply of liquid water likely cause enhanced physical weathering and high quarrying stresses. Following deglaciation, pronounced thermomechanical strain is induced and an active layer penetrates into the formerly perennially frozen bedrock. These factors likely cause the observed paraglacial rockfall increase close to the glacier surface. This paper, the first of two companion pieces, presents the most extensive dataset of high-alpine rockfall to date and the first systematic documentation of a cirque-wide erosion response of glaciated rockwalls to recent climate warming.

scholarly journals Application of inventory data for estimating characteristics of and regional climate-change effects on mountain glaciers: a pilot study with the European Alps

1995 ◽  
Vol 21 ◽  
pp. 206-212 ◽  
Author(s):  
Wilfried Haeberli ◽  
Martin Hoelzle
Keyword(s):  
Climate Change ◽  
Pilot Study ◽  
Mass Balance ◽  
Regional Climate ◽  
Ice Age ◽  
European Alps ◽  
Inventory Data ◽  
Mountain Glaciers ◽  
Climate Change Effects ◽  
Length Changes

A parameterization scheme using simple algorithms for unmeasured glaciers is being applied to glacier inventory data to estimate the basic glaciological characteristics of the inventoried ice bodies and simulate potential climate-change effects on mountain glaciers. For past and potential climate scenarios, glacier changes for assumed mass-balance changes are calculated as step functions between steady-state conditions for time intervals that approximately correspond to the characteristic dynamic response time (a few decades) of the glaciers. In order to test the procedure, a pilot study was carried out in the European Alps where detailed glacier inventories had been compiled around the mid-1970s. Total glacier volume in the Alps is estimated at about 130 km3 for the mid-1970s; strongly negative mass balances are likely to have caused a loss of about 10–20% of this total volume during the decade 1980–90. Backward calculation of glacier-length changes using a mean annual mass balance of 0.25m w.e.a−1 since the end of the “Little Ice Age” around 1850 AD gives considerable scatter but satisfactory overall results as compared with long-term observations. The total loss of Alpine surface ice mass since 1850 can be estimated at about half the original value. An acceleration of this development, with annual mass losses of around 1 m a−1 or more as anticipated from IPCC scenario A for the coming century, could eliminate major parts of the presently existing Alpine ice volume within decades.

scholarly journals Climate change and the global pattern of moraine-dammed glacial lake outburst floods

2018 ◽  
Vol 12 (4) ◽  
pp. 1195-1209 ◽  
Author(s):  
Stephan Harrison ◽  
Jeffrey S. Kargel ◽  
Christian Huggel ◽  
John Reynolds ◽  
Dan H. Shugar ◽  
...  
Keyword(s):  
Climate Change ◽  
Ice Age ◽  
Dam Failure ◽  
Glacial Lake ◽  
Glacier Recession ◽  
Outburst Floods ◽  
Glacial Lake Outburst Floods ◽  
Lake Formation ◽  
Recent Climate ◽  
Moraine Dam Failure

Abstract. Despite recent research identifying a clear anthropogenic impact on glacier recession, the effect of recent climate change on glacier-related hazards is at present unclear. Here we present the first global spatio-temporal assessment of glacial lake outburst floods (GLOFs) focusing explicitly on lake drainage following moraine dam failure. These floods occur as mountain glaciers recede and downwaste. GLOFs can have an enormous impact on downstream communities and infrastructure. Our assessment of GLOFs associated with the rapid drainage of moraine-dammed lakes provides insights into the historical trends of GLOFs and their distributions under current and future global climate change. We observe a clear global increase in GLOF frequency and their regularity around 1930, which likely represents a lagged response to post-Little Ice Age warming. Notably, we also show that GLOF frequency and regularity – rather unexpectedly – have declined in recent decades even during a time of rapid glacier recession. Although previous studies have suggested that GLOFs will increase in response to climate warming and glacier recession, our global results demonstrate that this has not yet clearly happened. From an assessment of the timing of climate forcing, lag times in glacier recession, lake formation and moraine-dam failure, we predict increased GLOF frequencies during the next decades and into the 22nd century.

Paraglacial responses in deglaciating cirque walls: Implications for rockfall magnitudes/frequencies and rockwall retreat

2020 ◽  
Author(s):  
Ingo Hartmeyer ◽  
Robert Delleske ◽  
Markus Keuschnig ◽  
Michael Krautblatter ◽  
Andreas Lang ◽  
...  
Keyword(s):  
European Alps ◽  
Atmospheric Conditions ◽  
Power Law Distribution ◽  
Glacier Surface ◽  
Negative Power ◽  
Terrestrial Lidar ◽  
Frequency Distributions ◽  
Ice Surface ◽  
Recent Climate ◽  
Glacial Landforms

<p>Over the past 150 years almost half of the glacier volume disappeared in the European Alps. Besides glacier retreat, ice surface lowering reflects much of the volume loss and uncovers the adjacent rockwalls. In steep glacial cirques, this process exposes rock to atmospheric conditions for the very first time in many millennia. Instability of rockwalls has long been identified as one of the direct consequences of deglaciation, but so far cirque-wide quantification of rockfall at high-resolution is missing and the proportional contributions of low-, mid- and high magnitude rockfalls have remained poorly constrained. <br>We use terrestrial LiDAR to establish a rockfall inventory for the permafrost-affected rockwalls of two rapidly deglaciating cirques in the Central Alps of Austria (Kitzsteinhorn). During six-year monitoring (2011-2017) 78 rockwall scans were acquired. Overall, we registered 632 rockfalls ranging from 0.003 to 879.4 m³, which concentrate along pre-existing structural weaknesses. 60 % of the rockfall volume detached from less than ten vertical meters above the glacier surface, indicating enhanced rockfall over tens of years following deglaciation. <br>Antecedent rockfall preparation is assumed to start when the rockwall is still ice-covered: Inside the Randkluft (gap between cirque wall and glacier) sustained freezing and sufficient water supply likely cause enhanced weathering and high plucking stresses. Following deglaciation, pronounced thermomechanical strain is induced and an active layer penetrates into perennially frozen bedrock, likely contributing to the observed paraglacial rockfall increase close to the glacier surface. <br>Observed mean cirque wall retreat of 1.9 mm a-1 ranks in the top range of reported values and is mainly driven by enhanced rockfall from the lowermost, freshly deglaciated sections of the investigated rockwalls. Rockfall magnitude-frequency distribution, which has never been quantified before for deglaciating cirques, follows a distinct negative power law distribution over four orders of magnitude. Magnitude-frequency distributions in glacier-proximal and glacier-distal rockwall sections differ significantly due to an increased occurrence of large rockfalls in recently deglaciated areas. The present study thus demonstrates how recent climate warming shapes glacial landforms, controls spatiotemporal rockfall variation in glacial environments and indicates an exhaustion law over decades for rockfall activity immediately following deglaciation crucial for future hazard assessments.</p>

scholarly journals Past climate changes and permafrost depth at the Lake El'gygytgyn site: implications from data and thermal modelling

2012 ◽  
Vol 8 (4) ◽  
pp. 2607-2644 ◽  
Author(s):  
D. Mottaghy ◽  
G. Schwamborn ◽  
V. Rath
Keyword(s):  
Temperature Profile ◽  
Climate Changes ◽  
Ground Surface ◽  
Temperature Data ◽  
Ice Age ◽  
Drilling Process ◽  
Cool Period ◽  
Past Climate ◽  
Recent Climate ◽  
Lake El’Gygytgyn

Abstract. We present results of numerical simulations of the temperature field of the subsurface around and beneath the crater Lake El'gygytgyn in NE Russia, which is subject of an interdisciplinary drilling campaign within the International Continental Drilling Program (ICDP). This study focuses on determining the permafrost depth and the transition between talik and permafrost regimes, both, under steady-state and transient conditions of past climate changes. Thermal properties of the subsurface are deduced from measurements on three representative core samples taken from the quaternary sediments and the underlying impact rock. Further information is derived from the available geophysical logs and literature data. The temperature data from the lake borehole ICDP site 5011-1 down to 400 m depth below lake bottom are dominated by thermal perturbations related to the drilling process, and thus only give reliable values for the lowermost value in the borehole. Undisturbed temperature data recorded over more than two years in the 140 m deep land-based borehole ICDP site 5011-3 allow to determine the mean annual ground surface temperature (GST), as well as its history (GSTH) to a certain extent. Although the borehole's depth is by far not sufficient for a complete reconstruction of past temperatures back to the last glacial maximum (LGM), the temperature data and our modelling results show that there is still an influence of the LGM on the thermal regime, and thus on the permafrost depth. Whereas the latter result is obtained from the deeper part of the temperature profile, the rather strong curvature of the temperature data in shallower depths around 30 m can be explained by a comparatively large amplitude of the Little Ice Age (LIA), with a subsequently persistent cool period. Other mechanisms like varying porosity may also have an influence on the temperature profile, however, our modelling studies imply a major contribution from recent climate changes.

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