Recent, rapid and profound changes to glacier morphology and dynamics, Juneau Icefield, Alaska

2021 ◽  
Author(s):  
Bethan Davies ◽  
Jacob Bendle ◽  
Robert McNabb ◽  
Jonathan Carrivick ◽  
Christopher McNeil ◽  
...  
Keyword(s):  
Little Ice Age ◽  
Ice Age ◽  
Aerial Photographs ◽  
Equilibrium Line Altitude ◽  
Regional Warming ◽  
Geomorphological Mapping ◽  
Glacier Recession ◽  
Digital Elevation ◽  
High Resolution Satellite Imagery ◽  
Global Sea Level

<p>The Alaskan region (comprising glaciers in Alaska, British Columbia and Yukon) contains the third largest ice volume outside of the Greenland and Antarctic ice sheets, and contributes more to global sea level rise than any other glacierised region defined by the Randolph Glacier Inventory. However, ice loss in this area is not linear, but in part controlled by glacier hypsometry as valley and outlet glaciers are at risk of becoming detached from their accumulation areas during thinning. Plateau icefields, such as Juneau Icefield in Alaska, are very sensitive to changes in Equilibrium Line Altitude (ELA) as this can result in rapidly shrinking accumulation areas. Here, we present detailed geomorphological mapping around Juneau Icefield and use this data to reconstruct the icefield during the “Little Ice Age”. We use topographic maps, archival aerial photographs, high-resolution satellite imagery and digital elevation models to map glacier lake and glacier area and volume change from the Little Ice Age to the present day (1770, 1948, 1979, 1990, 2005, 2015 and 2019 AD). Structural glaciological mapping (1979 and 2019) highlights structural and topographic controls on non-linear glacier recession.  Our data shows pronounced glacier thinning and recession in response to widespread detachment of outlet glaciers from their plateau accumulation areas. Glacier detachments became common after 2005, and occurred with increasing frequency since then. Total summed rates of area change increased eightfold from 1770-1948 (-6.14 km<sup>2</sup> a<sup>-1</sup>) to 2015-2019 (-45.23 km<sup>2</sup> a<sup>-1</sup>). Total rates of recession were consistent from 1770 to 1990 AD, and grew increasingly rapid after 2005, in line with regional warming.</p>

Glacier changes since the Little Ice Age maximum in the western Qilian Shan, northwest China, and consequences of glacier runoff for water supply

2003 ◽  
Vol 49 (164) ◽  
pp. 117-124 ◽  
Author(s):  
Liu Shiyin ◽  
Sun Wenxin ◽  
Shen Yongping ◽  
Li Gang
Keyword(s):  
Little Ice Age ◽  
Image Data ◽  
Northwest China ◽  
Ice Age ◽  
Aerial Photographs ◽  
Equilibrium Line Altitude ◽  
North West ◽  
Glacier Changes ◽  
Glacier Runoff ◽  
Topographical Maps

AbstractBased on aerial photographs, topographical maps and the Landsat-5 image data, we have analyzed fluctuations of glaciers in the western Qilian Shan, north-west China, from the Little Ice Age (LIA) to 1990. The areas and volumes of glaciers in the whole considered region decreased 15% and 18%, respectively, from the LIA maximum to 1956. This trend of glacier shrinkage continued and accelerated between 1956 and 1990. These latest decreases in area and volume were about 10% in 34 years. The recent shrinkage may be due either to a combination of higher temperatures and lower precipitation during the period 1956–66, or to continuous warming in the high glacierized mountains from 1956 to 1990. As a consequence, glacier runoff from ice wastage between 1956 and 1990 has increased river runoff by 6.2 km3 in the four river basins under consideration. Besides, the equilibrium-line altitude (ELA) rise estimated from the mean terminus retreat of small glaciers <1 km long is 46 m, which corresponds to a 0.3°C increase of mean temperatures in warm seasons from the LIA to the 1950s.

A chronology of the Little Ice Age in the tropical Andes of Bolivia (16°S) and its implications for climate reconstruction

2008 ◽  
Vol 70 (2) ◽  
pp. 198-212 ◽  
Author(s):  
Antoine Rabatel ◽  
Bernard Francou ◽  
Vincent Jomelli ◽  
Philippe Naveau ◽  
Delphine Grancher
Keyword(s):  
20Th Century ◽  
Little Ice Age ◽  
18Th Century ◽  
Extreme Values ◽  
Ice Age ◽  
Tropical Andes ◽  
Equilibrium Line Altitude ◽  
Mountain Areas ◽  
Study Region ◽  
Glacier Recession

AbstractDating moraines by lichenometry enabled us to reconstruct glacier recession in the Bolivian Andes since the Little Ice Age maximum. On the 15 proglacial margins studied, we identified a system of ten principal moraines that marks the successive positions of glaciers over the last four centuries. Moraines were dated by performing statistical analysis of lichen measurements based on the extreme values theory. Like glaciers in many mid-latitude mountain areas, Bolivian glaciers reached their maximal extent during the second half of the 17th century. This glacier maximum coincides with the Maunder minimum of solar irradiance. By reconstructing the equilibrium-line altitude and changes in mass-balance, we think the glacier maximum may be due to a 20 to 30% increase in precipitation and a 1.1 to 1.2 °C decrease in temperature compared with present conditions. In the early 18th century, glaciers started to retreat at varying rates until the late 19th to early 20th century; this trend was generally associated with decreasing accumulation rates. By contrast, glacier recession in the 20th century was mainly the consequence of an increase in temperature and humidity. These results are consistent with observations made in the study region based on other proxies.

scholarly journals Glacier recession on Cerro Charquini (16° S), Bolivia, since the maximum of the Little Ice Age (17th century)

2006 ◽  
Vol 52 (176) ◽  
pp. 110-118 ◽  
Author(s):  
Antoine Rabatel ◽  
Abraham Machaca ◽  
Bernard Francou ◽  
Vincent Jomelli
Keyword(s):  
20Th Century ◽  
Little Ice Age ◽  
17Th Century ◽  
Climatic Conditions ◽  
Ice Age ◽  
Equilibrium Line Altitude ◽  
Glacier Recession ◽  
Recession Rates ◽  
Cordillera Real ◽  
The 19Th Century

AbstractCerro Charquini, Bolivia (Cordillera Real, 5392 ma.s.l.) was selected as a site to reconstruct glacier recession since the maximum of the Little Ice Age (LIA) in the central Andes. Five glaciers, located on differently exposed slopes, present comprehensive and well-preserved morainic systems attributed to former centuries. The moraines were dated by lichenometry and show a consistent organization on the different slopes. The past geometry of the glaciers was reconstructed using ground topography and aerophotogrammetry. Lichenometric dating shows that the LIA maximum occurred in the second half of the 17th century, after which the glaciers have receded nearly continuously. Over the last decades of the 20th century (1983–97), recession rates increased by a factor of four. On the northern and western slopes, glaciers receded more than on the southern and eastern slopes (by 78% and 65% of their LIA maximum area, respectively). The mean equilibrium-line altitude (ELA) rose by about 160 m between the LIA maximum and 1997. Recession rates were analysed in terms of climatic signal, suggesting that glacier recession since the LIA maximum was mainly due to a change in precipitation and that the 19th century may have been drier. For the 20th century, a temperature rise of about 0.6°C appears to be the main cause of glacier recession. Recent climatic conditions from 1983 to 1997 correspond to a mass deficit of about 1.36m w.e.a–1. If such conditions persist, the small glaciers below 5300ma.s.l. in the Cordillera Real should disappear completely in the near future.

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’.

Modeling the retreat of the Aneto Glacier (Spanish Pyrenees) since the Little Ice Age, and its accelerated shrinkage over recent decades

The Holocene ◽  
2021 ◽  
pp. 095968362110116
Author(s):  
Néstor Campos ◽  
Jesús Alcalá-Reygosa ◽  
Scott C Watson ◽  
Ioannis Kougkoulos ◽  
Adolfo Quesada-Román ◽  
...  
Keyword(s):  
Climatic Conditions ◽  
Ice Age ◽  
Aerial Photographs ◽  
Ice Thickness ◽  
Equilibrium Line Altitude ◽  
Massif Central ◽  
Perfectly Plastic ◽  
M 10 ◽  
Digital Elevation ◽  
Elevation Model

The Aneto, located on the Maladeta Massif (Central Pyrenees), is the largest glacier of the Pyrenees. The glacier is 675 m long, occupies an area of 48.64 ha and has a maximum altitude of 3269 m. In this study, we present a detailed area, volume, ice thickness, and Equilibrium Line Altitude reconstruction of the glacier for different periods (LIA, 1957, 1983, 2000, 2006, 2015, and 2017) and analyze its retreat. To estimate the glacier extent during the LIA, the moraines were mapped by using photo interpretation techniques whereas for the recent stages digital satellite images and aerial photographs were used. Moreover, we estimated the topography of the glacier using a simple steady-state model that assumes a perfectly plastic ice rheology, which allowed reconstructing the theoretical ice profiles of the glacier. To reconstruct the ice surface, a digital elevation model was created and combined with the bedrock topography in order to obtain the ice thickness of each stage. The results of the study reveal a considerable retreat of the Aneto Glacier since the LIA. The length of the glacier has reduced from 1970 to 675 m from LIA to2017, and its tongue has retreated from 2385 to 3029 m a.s.l. Furthermore, the glaciated area has been reduced from 245 to 48.64 ha from LIA to 2017 and the ELA has risen from 2919 to 3139 m a.s.l. The data obtained indicates that in the LIA–2017 period the glacier volume has been reduced from 82.57 m × 106 m3 to 3.48 m × 106 m3 and the maximum ice thickness from 95 to 27m. We also reconstructed the climatic conditions, showing an increase in temperature of ~1.14°C from LIA to 2017. These data reveal a vast retreat of the glacier since the LIA, which has accelerated since the 1980’s and even more since the year 2000.

scholarly journals Skaftafellsjökull, Iceland: glacial geomorphology recording glacier recession since the Little Ice Age

2017 ◽  
Vol 13 (2) ◽  
pp. 358-368 ◽  
Author(s):  
David J. A. Evans ◽  
Marek Ewertowski ◽  
Chris Orton
Keyword(s):  
Little Ice Age ◽  
Ice Age ◽  
Glacial Geomorphology ◽  
Glacier Recession

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 Evidências Geomorfológicas de Mudanças Ambientais na Baía Esperança, Península Antártica

2019 ◽  
Vol 37 ◽  
pp. 137-149
Author(s):  
Rafaela Mattos Costa ◽  
Carina Petsch ◽  
Maria Eliza Sotille ◽  
Katia Kellem da Rosa ◽  
Jefferson Cardia Simões ◽  
...  
Keyword(s):  
Little Ice Age ◽  
Buenos Aires ◽  
Environmental Changes ◽  
Ice Age ◽  
Physical Weathering ◽  
Geomorphological Mapping ◽  
Transport Distance ◽  
Coarse Grains ◽  
Geomorphological Features ◽  
Sentinel 2

A geomorphological interpretation of the glacial geomorphology of the proglacial environments of the Buenos Aires, Kenney and Flora glaciers in Hope Bay, Antarctica, between the coordinates 63° 23'S and 63° 26'S latitude and 56° 8'W and 57° 4'W longitude. Sedimentary, granulometric and morphological analyzes were carried out on 15 samples collected in 2017 for the identification of depositional geomorphological features and subsequent geomorphological mapping. The glacier fronts were delineated from Sentinel-2 and Quickbird images of 1988, 2008 and 2017 using the ArcGIS® software to identify the landforms chronology of the shapes. The higher number of coarse grains, low selection, and high values of C40 in all samples indicate modification by erosive processes in supraglacial environment and/or transport distance after substrate quarrying process and grain fracturing by post-depositional physical weathering. The reconstruction of the Hope Bay’s Holocene landscape of indicates glaciers with tens of meters of advance compared to the current front during the Little Ice Age (LIA). The geomorphological mapping and sedimentary analyzes showed recent environmental changes in the proglacial system, with formation of hummocky moraines indicating the retreat/stabilization of the glaciers in the LIA. Furthermore, they set evidences of recent recession moraines, which prevail in the Buenos Aires Glacier predominate in the 2008-2017 phase, on the Flora Glacier in 1988-2008 period and the Kenney Glacier in the 2008-2017 period.

scholarly journals Mapping glaciers in Jotunheimen, South-Norway, during the "Little Ice Age" maximum

2009 ◽  
Vol 3 (2) ◽  
pp. 231-243 ◽  
Author(s):  
S. Baumann ◽  
S. Winkler ◽  
L. M. Andreassen
Keyword(s):  
Little Ice Age ◽  
18Th Century ◽  
Field Measurements ◽  
Geographical Information ◽  
Ice Age ◽  
Inventory Data ◽  
Digital Elevation ◽  
Remote Sensing Techniques ◽  
Southern Norway ◽  
Elevation Model

Abstract. The maximum glacier extent during the "Little Ice Age" (mid 18th century AD) in Jotunheimen, southern Norway, was mapped using remote sensing techniques. Interpretation of existing glaciochronological studies, analysis of geomorphological maps, and own GPS-field measurements were applied for validation of the mapping. The length of glacier centrelines and other inventory data were determined using a Geographical Information System (GIS) and a Digital Elevation Model. "Little Ice Age" maximum extent for a total of 233 glaciers comprising an overall glacier area of about 290 km2 was mapped. Mean length of the centreline was calculated to 1.6 km. Until AD 2003, the area and length shrank by 35% and 34%, respectively, compared with the maximum "Little Ice Age" extent.

scholarly journals Estimating the longevity of glaciers in the Xinjiang region of the Tian Shan through observations of glacier area change since the Little Ice Age using high-resolution imagery

2020 ◽  
Vol 66 (257) ◽  
pp. 471-484
Author(s):  
Julia Liu ◽  
Daniel E. Lawson ◽  
Robert L. Hawley ◽  
Jonathan Chipman ◽  
Brian Tracy ◽  
...  
Keyword(s):  
High Resolution ◽  
Little Ice Age ◽  
Ice Age ◽  
Glacier Area ◽  
Glacier Surface ◽  
Relative Loss ◽  
High Resolution Imagery ◽  
High Resolution Satellite Imagery ◽  
Kaidu River ◽  
Tian Shan

AbstractGlacial retreat in response to warming climates in the arid Xinjiang region of northwestern China directly impacts downstream water resources available for local communities. We used high-resolution satellite imagery from 1969 to 2014 to delineate spatial changes in 54 active glaciers in the upper Kaidu River Basin in the Tian Shan as well as their past expanses during the Little Ice Age (LIA). We manually delineated their boundaries based on the interpretation of glacial, geomorphic and topographic features. From the total glacier surface area, we estimated glacier volume and mass. From 1969 to 2014, glacier area decreased by 10.1 ± 1.0 km2 (relative loss of 34.2 ± 3.5%) and mass by 1.025 ± 0.108 Gt (relative loss of 43 ± 4.6%). From the LIA maximum (est. 1586 CE) to 1969, relative losses were less (25.7 ± 4.3% area loss and 33.1 ± 5.7% mass loss). Our results indicate that glacier recession is accelerating over time and that the glaciers are currently losing over 1.5 times more relative area than elsewhere in the Tian Shan. Using linear and non-linear projections, we estimate that these glaciers may disappear between 2050 and 2150 CE if climatic warming continues at the same pace.

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