The Claps of Luc-en-Diois (Drôme, SE France) : evaluation of a lake fill volume based on a morphological model

2004 ◽  
Vol 175 (3) ◽  
pp. 303-312 ◽  
Author(s):  
Gilles Brocard
Keyword(s):  
Little Ice Age ◽  
River Sediment ◽  
Sediment Load ◽  
Ice Age ◽  
Drainage Network ◽  
Erosion Rates ◽  
Lake Volume ◽  
Fill Volume ◽  
Morphological Model ◽  
The Mean

Abstract The Claps Lake near Luc-en-Diois is a naturally dammed palaeo-lake fed by the Drôme River sediment load during the Little Ice Age (LIA). The present assessment is based on a valley reconstruction using a geomorphic model. It illustrates the potentiality and limits of the geomorphic analysis to accurately predict the buried topography. This method indeed may help to reduce the prospecting work required in classical evaluations of fill volumes of such natural dams. The lake was rapidly filled with sediments, indicating enhanced erosion of the watershed during the LIA. Several studies have attempted to quantify the volume of the lake fill and use it to assess erosion rates during the LIA. Very little is known, however, about the geometry of the buried valley. Estimated lake volumes and erosion rates vary depending on how the buried valley is reconstructed and what correcting factors are used for calculating erosion rates. The present assessment is based on a valley reconstruction using a geomorphic model calibrated by the surrounding drainage network, as well as the introduction of correcting factors that improve the corrections applied in the previous works. The resulting lake volume is 71–81.106 m3, and the mean erosion rate at 0.7-1.2 mm.yr-1, a high value compared to previous estimates. This rate is compared to the results obtained by various methods and over different timescales in the surrounding region.

scholarly journals Glacier equilibrium line altitude variations during the “Little Ice Age” in the Mediterranean Andes (30◦–37◦ S)

2019 ◽  
Author(s):  
Álvaro González-Reyes ◽  
Claudio Bravo ◽  
Mathias Vuille ◽  
Martin Jacques-Coper ◽  
Maisa Rojas ◽  
...  
Keyword(s):  
Little Ice Age ◽  
Pearson Correlation ◽  
Temporal Changes ◽  
Global Climate Models ◽  
Ice Age ◽  
Equilibrium Line ◽  
Equilibrium Line Altitude ◽  
Mountainous Regions ◽  
The Mean ◽  
The Mediterranean

Abstract. The "Little Ice Age" (LIA; 1500–1850 Common Era (CE)), has long been recognized as the last period when mountain glaciers in many regions of the Northern Hemisphere (NH) recorded extensive growth intervals in terms of their ice mass and frontal position. The knowledge about this relevant paleoclimatic interval is vast in mountainous regions such as the Alps and Rocky Mountains in North America. However, in extra-tropical Andean sub-regions such as the Mediterranean Andes of Chile and Argentina (MA; 30º–37º S), the LIA has been poorly documented. Paradoxically, the few climate reconstructions performed in the MA based on lake sediments and tree rings do not show clear evidence of a LIA climate anomaly as observed in the NH. In addition, recent studies have demonstrated temporal differences between mean air temperature variations across the last millennium between both hemispheres. This motivates our hypothesis that the LIA period was not associated with a significant climate perturbation in the MA region. Considering this background, we performed an experiment using daily climatic variables from three Global Climate Models (GCMs) to force a novel glaciological model. In this way, we simulated temporal variations of the glacier equilibrium-line altitude (ELA) to evaluate the glacier response during the period 1500–1848 CE. Overall, each GCM shows temporal changes in annual ELA, with anomalously low elevations during 1640–1670 and 1800–1848 CE. An interval with high ELA values was identified during 1550–1575 CE. The spectral properties of the mean annual ELA in each GCM present significant periodicities between 2–7 years, and also significant decadal to multi-decadal signals. In addition, significant and coherent cycles at interannual to multi-decadal scales were detected between modeled mean annual ELAs and the first EOF1 extracted from Sea Surface Temperature (SST) within the El Niño 3.4 of each GCM. Finally, significant Pearson correlation coefficients were obtained between the mean annual ELA and Pacific SST on interannual to multi-decadal timescales. According to our findings, we propose that Pacific SST variability was the main modulator of temporal changes of the ELA in the MA region of South America during 1500–1848 CE.

scholarly journals The ENSO teleconnections to the Indian summer monsoon climate through the Last Millennium as simulated by the PMIP3

2018 ◽  
Author(s):  
Charan Teja Tejavath ◽  
Karumuri Ashok ◽  
Supriyo Chakraborty ◽  
Rengaswamy Ramesh
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Little Ice Age ◽  
Walker Circulation ◽  
Summer Monsoon Rainfall ◽  
Ice Age ◽  
Boreal Summer ◽  
Last Millennium ◽  
Enso Teleconnections ◽  
The Mean

Abstract. Using seven model simulations from the PMIP3, we study the mean summer (June–September) climate and its variability in India during the Last Millennium (LM; CE 850–1849) with emphasis on the Medieval Warm Period (MWP) and Little Ice Age (LIA), after validation of the simulated current day climate and trends. We find that the above (below) LM-mean summer global temperatures during the MWP (LIA) are associated with relatively higher (lower) number of concurrent El Niños as compared to La Niñas. The models simulate higher (lower) Indian summer monsoon rainfall (ISMR) during the MWP (LIA). This is notwithstanding a strong simulated negative correlation between the timeseries of NINO3.4 index and that of the area-averaged ISMR, Interestingly, the percentage of strong El Niños (La Niñas) causing negative (positive) ISMR anomalies is higher in the LIA (MWP), a non-linearity that apparently is important for causing higher ISMR in the MWP. Distribution of simulated boreal summer velocity potential at 850 hPa during MWP in models, in general, shows a zone of anomalous convergence in the central tropical Pacific flanked by two zones of divergence, suggesting a westward shift in the Walker circulation as compared to the simulations for LM as well as and a majority of historical simulations, and current day observed signal. The anomalous divergence centre in the west also extends into the equatorial eastern Indian Ocean, resulting in an anomalous convergence zone over India and therefore excess rainfall during the MWP as compared to the LM; the results are qualitative, given the inter-model spread.

scholarly journals Accelerating retreat and high-elevation thinning of glaciers in central Spitsbergen

2016 ◽  
Vol 10 (3) ◽  
pp. 1317-1329 ◽  
Author(s):  
Jakub Małecki
Keyword(s):  
Little Ice Age ◽  
High Elevation ◽  
Comprehensive Analysis ◽  
Ice Age ◽  
The Arctic ◽  
Digital Elevation ◽  
Glacier Changes ◽  
The Mean ◽  
Geodetic Mass Balance ◽  
The 1960S

Abstract. Svalbard is a heavily glacier-covered archipelago in the Arctic. Dickson Land (DL), in the central part of the largest island, Spitsbergen, is relatively arid and, as a result, glaciers there are relatively small and restricted mostly to valleys and cirques. This study presents a comprehensive analysis of glacier changes in DL based on inventories compiled from topographic maps and digital elevation models for the Little Ice Age (LIA) maximum, the 1960s, 1990, and 2009/2011. Total glacier area has decreased by  ∼ 38 % since the LIA maximum, and front retreat increased over the study period. Recently, most of the local glaciers have been consistently thinning in all elevation bands, in contrast to larger Svalbard ice masses which remain closer to balance. The mean 1990–2009/2011 geodetic mass balance of glaciers in DL is among the most negative from the Svalbard regional means known from the literature.

scholarly journals Extension of Glacier de Saint-Sorlin, French Alps, and equilibrium-line altitude during the Little Ice Age

2002 ◽  
Vol 48 (160) ◽  
pp. 118-124 ◽  
Author(s):  
Louis Lliboutry
Keyword(s):  
Little Ice Age ◽  
Meteorological Data ◽  
Vertical Gradient ◽  
Winter Precipitation ◽  
Ice Age ◽  
Equilibrium Line ◽  
Equilibrium Line Altitude ◽  
French Alps ◽  
The Mean ◽  
Accumulation Area Ratio

AbstractGlacier de Saint-Sorlin, French Alps, left terminal moraines at 1.3, 2.9 and 3.7 km ahead of the present terminus. According to proxy data and to historical maps, these were formed in the 19th, 18th and 17th centuries, respectively. A plateau at 2700–2625 m was then surrounded by ice but never became an accumulation area. This fact shows that the equilibrium-line altitude (ELA) on the glacier never dropped below 2300 m. The following simple models apply sufficiently to yield reliable estimations of past ELA: (1) a uniform and constant vertical gradient of the mass balance, down to the terminus; and (2) a plane bed, with a slope of 8.5° and a uniform width. Then in a steady situation the accumulation–area ratio is 1/2. Compared to the mean for 1956–72, at the onset of the Little Ice Age the balances were higher by 3.75 m ice a−1, and the ELA was 400 m lower. Correlations between 1956–72 balances and meteorological data suggest that during the melting season the 0°C isotherm was about 800 m lower, while the winter precipitation at low altitudes did not change. These correlations may have been different in the past, but an equal lowering of the ELA and of the 0°C isotherm, as assumed by several authors, seems excluded.

Holocene climatic change, 14 C wiggles and variations in solar irradiance

1990 ◽  
Vol 330 (1615) ◽  
pp. 547-560 ◽  
Keyword(s):  
Energy Balance ◽  
21St Century ◽  
Solar Irradiance ◽  
Little Ice Age ◽  
Climate Model ◽  
Maunder Minimum ◽  
Ice Age ◽  
Gas Concentration ◽  
The Mean ◽  
Glacial Advance

Evidence from the advances and retreats of alpine glaciers during the Holocene suggests that there were at least 14 century-timescale cool periods similar to the recent Little Ice Age. Here, we examine the hypothesis that these cool periods were caused by reductions in solar irradiance. A statistically significant correlation is found between the global glacial advance and retreat chronology of Röthlisberger and variations in atmospheric 14 C concentration. A simple energy-balance climate model is used to show that the mean reduction of solar irradiance during times of maximum 14 C anomaly like the Maunder Minimum would have to have been between 0.22 and 0.55 % to have caused these cool periods. If a similar solar irradiance perturbation began early in the 21st century, the associated climate effects would be noticeable, but still considerably less than those expected to result from future greenhouse gas concentration increases.

High sensitivity of North Iceland (Tröllaskagi) debris-free glaciers to climatic change from the ‘Little Ice Age’ to the present

The Holocene ◽  
2017 ◽  
Vol 27 (8) ◽  
pp. 1187-1200 ◽  
Author(s):  
José María Fernández-Fernández ◽  
Nuria Andrés ◽  
Þorsteinn Sæmundsson ◽  
Skafti Brynjólfsson ◽  
David Palacios
Keyword(s):  
20Th Century ◽  
Air Temperature ◽  
Little Ice Age ◽  
Satellite Image ◽  
High Sensitivity ◽  
Ice Age ◽  
Aerial Photographs ◽  
Early 20Th Century ◽  
Equilibrium Line Altitude ◽  
The Mean

The Tröllaskagi peninsula is located in northern Iceland, between meridian 19°30′W and 18°10′W, jutting out into the North Atlantic to latitude 66°12′N. The aim of this research is to study recent glacier changes in relation to climatic evolution of the Gljúfurárjökull and Tungnahryggsjökull debris-free valley glaciers in Tröllaskagi. Glacier extent mapping and spatial analysis operations were performed with ArcGIS (ESRI), using analysis of aerial photographs from 1946, 1985, 1994 and 2000, and a 2005 SPOT satellite image. The results show that these glaciers lost a quarter of their surface area between the ‘Little Ice Age’ and 2005. In this paper, the term ‘Little Ice Age’ follows Grove (2001) as the most recent period when glaciers extended globally between the medieval period and the early 20th century. The abrupt climatic transition of the early 20th century and the 25-year warm period 1925–1950 triggered the main retreat and volume loss of these glaciers since the end of the ‘Little Ice Age’. Meanwhile, cooling during the 1960s, 1970s and 1980s altered the trend, with advances of the glacier snouts. Between the ‘Little Ice Age’ and the present day, the mean annual air temperature and mean ablation season air temperature increased by 1.9°C and 1.5°C, respectively, leading to a 40–50 m rise in the equilibrium line altitude (ELA) of the glaciers during this period. The response of these glaciers depends not only on the mean ablation season air temperature evolution but also on other factors such as winter precipitation. The models applied show a precipitation increase of up to more than 700 mm since the ‘Little Ice Age’.

Initial Establishment of Saxicolous Lichens Following Recent Glacial Recession in Sverdrup Pass, Ellesmere Island, Canada

1988 ◽  
Vol 20 (3) ◽  
pp. 253-268 ◽  
Author(s):  
Dianne Fahselt ◽  
Paul F. Maycock ◽  
Josef Svoboda
Keyword(s):  
Little Ice Age ◽  
High Arctic ◽  
Ellesmere Island ◽  
Ice Age ◽  
Natural Conditions ◽  
Bare Rock ◽  
Lichen Diversity ◽  
Valley Glacier ◽  
The Mean ◽  
Saxicolous Lichens

AbstractIn the recently deglaciated zone of a valley glacier in Central Ellesmere Island the mean period of time before the onset of colonization on bare rock surfaces was estimated to be about 80 years. The first species to establish was Xanthoria elegans, followed by Lecanora crenulata and Umbilicaria virginis approximately 20 years later. Summer temperature appeared to be one factor which affected lichen establishment in recently deglaciated bare areas in the High Arctic. Warmer microsites were identified as preferred locations for thallus establishment; these, therefore, constitute ideal sites for studies of thallus initiation under natural conditions. Following the retreat of a glacier from its most advanced Little Ice Age position, 16 species of saxicolous lichens have become established on bare rock debris in the icefree zone, but in nine transects only five species had a constancy of 80% or more. Lichen diversity in this successional photocommunity was comparable to that in a nearby pre-Little Ice Age landscape with more varied substrata.

scholarly journals The Current Oxygen and Hydrogen Isotopic Status of Lake Baikal

Water ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 3476
Author(s):  
Andrey Fedotov ◽  
Ruslan Gnatovsky ◽  
Vadim Blinov ◽  
Maria Sakirko ◽  
Valentina Domysheva ◽  
...  
Keyword(s):  
Steady State ◽  
Isotopic Composition ◽  
Lake Baikal ◽  
Little Ice Age ◽  
Regional Climate ◽  
Ice Age ◽  
Mean Values ◽  
Baikal Basin ◽  
The Past ◽  
The Mean

This study revises the δ18O and δ2H status of Lake Baikal. The mean values of δ18O and δ2H varied from −15.9 to −15.5‰ and from −123.2 to 122.2‰, respectively, for the past 30 yr. The isotopic composition of the lake remained more ‘‘light” compared to the regional precipitation and rivers inflows. The isotopic composition of the lake has begun to change since ca.1920 after the Little Ice Age; however, Lake Baikal still has not reached the isotopically steady state in the present. The calculated composition of the steady-state should be −12.3‰ for δ18O and −103.6‰ for δ2H. If regional climate parameters do not change dramatically, Lake Baikal will reach these values in ca. 226 yr. Based on isotopic fingerprints of the upper (0 to 150 m) and near-bottom layers (ca. 150 m from the bottom floor), the renewal in the southern and central basins of Lake Baikal has occurred recently compared to the northern Baikal basin, and the size of the mixing-cell of downwelling is close to 30 km.

Variations in Sediment yield Over the Advance and Retreat of a Calving Glacier, Laguna San Rafael, North Patagonian Icefield

2010 ◽  
Vol 73 (1) ◽  
pp. 84-95 ◽  
Author(s):  
Michèle Koppes ◽  
Richard Sylwester ◽  
Andres Rivera ◽  
Bernard Hallet
Keyword(s):  
Little Ice Age ◽  
Ice Age ◽  
Sediment Yields ◽  
Acoustic Data ◽  
Erosion Rates ◽  
Continental Shelves ◽  
Glacier Dynamics ◽  
Tidewater Glacier ◽  
San Rafael ◽  
Glacial Advance

Bathymetric and sub-bottom acoustic data were collected in Laguna San Rafael, Chile, to determine sediment yields during the Little Ice Age advance and subsequent retreat of San Rafael Glacier. The sediment volumes and subaqueous landforms imaged are used to interpret the proglacial dynamics and estimate erosion rates from a temperate tidewater glacier over a complete advance–retreat cycle. Sediment yields from San Rafael Glacier averaged 2.7 × 10 m/a since the end of the Little Ice Age, circa AD 1898, corresponding to average basin-wide erosion rates of 23 ± 9 mm/a; the highest erosion rates, 68 ± 23 mm/a, occurred at the start of the retreat phase, and have since been steadily decreasing. Erosion rates were much lower during glacial advance, averaging at most 7 mm/a, than during retreat. Such large glacial sediment yields over two centuries of advance and retreat suggest that the contribution of sediments stored subglacially cannot account for much of the sediment being delivered to the terminus today. The detailed sub-bottom information of a proglacial lagoon yields important clues as to the timing of erosion, deposition and transfer of glacigenic sediments from orogens to the continental shelves, and the influence of glacier dynamics on this process.

scholarly journals Tracing glacier changes in Austria from the Little Ice Age to the present using a lidar-based high-resolution glacier inventory in Austria

2015 ◽  
Vol 9 (2) ◽  
pp. 753-766 ◽  
Author(s):  
A. Fischer ◽  
B. Seiser ◽  
M. Stocker Waldhuber ◽  
C. Mitterer ◽  
J. Abermann
Keyword(s):  
High Resolution ◽  
Little Ice Age ◽  
Ice Age ◽  
Relative Area ◽  
Glacier Area ◽  
Regional Variability ◽  
Glacier Inventory ◽  
Digital Elevation ◽  
Glacier Changes ◽  
The Mean

Abstract. Glacier inventories provide the basis for further studies on mass balance and volume change, relevant for local hydrological issues as well as for global calculation of sea level rise. In this study, a new Austrian glacier inventory has been compiled, updating data from 1969 (GI 1) and 1998 (GI 2) based on high-resolution lidar digital elevation models (DEMs) and orthophotos dating from 2004 to 2012 (GI 3). To expand the time series of digital glacier inventories in the past, the glacier outlines of the Little Ice Age maximum state (LIA) have been digitalized based on the lidar DEM and orthophotos. The resulting glacier area for GI 3 of 415.11 ± 11.18 km2 is 44% of the LIA area. The annual relative area losses are 0.3% yr−1 for the ~119-year period GI LIA to GI 1 with one period with major glacier advances in the 1920s. From GI 1 to GI 2 (29 years, one advance period of variable length in the 1980s) glacier area decreased by 0.6% yr−1 and from GI 2 to GI 3 (10 years, no advance period) by 1.2% yr−1. Regional variability of the annual relative area loss is highest in the latest period, ranging from 0.3 to 6.19% yr−1. The mean glacier size decreased from 0.69 km2 (GI 1) to 0.46 km2 (GI 3), with 47% of the glaciers being smaller than 0.1 km2 in GI 3 (22%).

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