scholarly journals Glacial areas, lake areas, and snowlines from 1975 to 2012: status of the Cordillera Vilcanota, including the Quelccaya Ice Cap, northern central Andes, Peru

2013 ◽  
Vol 7 (1) ◽  
pp. 573-634 ◽  
Author(s):  
M. N. Hanshaw ◽  
B. Bookhagen
Keyword(s):  
Confidence Interval ◽  
Spectral Unmixing ◽  
Second Step ◽  
Limited Attention ◽  
Lake Area ◽  
Tropical Andes ◽  
The Past ◽  
Ice Cap ◽  
Downstream Communities ◽  
Quelccaya Ice Cap

Abstract. Glaciers in the tropical Andes of southern Peru have received limited attention compared to glaciers in other regions (both near and far), yet remain of vital importance to agriculture, fresh water, and hydropower supplies of downstream communities. Little is known about recent glacial-area changes and how the glaciers in this region respond to climate changes, and, ultimately, how these changes will affect lake and water supplies. To remedy this, we have used 144 multi-spectral satellite images spanning almost four decades, from 1975–2012, to obtain glacial and lake-area outlines for the understudied Cordillera Vilcanota region, including the Quelccaya Ice Cap. In a second step, we have estimated the snowline altitude of the Quelccaya Ice Cap using spectral unmixing methods. We have made the following four key observations: first, since 1988 glacial areas throughout the Cordillera Vilcanota have been declining at a rate of 5.46 ± 1.70 km2 yr−1 (22-yr average, 1988–2010, with 95% confidence interval). The Quelccaya Ica Cap, specifically, has been declining at a rate of 0.67 ± 0.18 km2 yr−1 since 1980 (31-yr average, 1980–2011, also with 95% confidence interval); Second, decline rates for individual glacierized regions have been accelerating during the past decade (2000–2011) as compared to the preceding decade (1990–2000); Third, the snowline of the Quelccaya Ice Cap is retreating to higher elevations as glacial areas decrease, by a total of almost 300 m between its lowest recorded elevation in 1989 and its highest in 1998; and fourth, as glacial regions have decreased, 61% of lakes connected to glacial watersheds have shown a roughly synchronous increase in lake area, while 84% of lakes not connected to glacial watersheds have remained stable or have declined in area. Our new and detailed data on glacial and lake areas over 37 yr provide an important spatiotemporal assessment of climate variability in this area. These data can be integrated into further studies to analyze inter-annual glacial and lake-area changes and assess hydrologic dependence and consequences for downstream populations.

scholarly journals Glacial areas, lake areas, and snow lines from 1975 to 2012: status of the Cordillera Vilcanota, including the Quelccaya Ice Cap, northern central Andes, Peru

2014 ◽  
Vol 8 (2) ◽  
pp. 359-376 ◽  
Author(s):  
M. N. Hanshaw ◽  
B. Bookhagen
Keyword(s):  
Satellite Images ◽  
Climate Changes ◽  
Spectral Unmixing ◽  
Limited Attention ◽  
Lake Area ◽  
Tropical Andes ◽  
The Past ◽  
Ice Cap ◽  
Downstream Communities ◽  
Quelccaya Ice Cap

Abstract. Glaciers in the tropical Andes of southern Peru have received limited attention compared to glaciers in other regions (both near and far), yet remain of vital importance to agriculture, fresh water, and hydropower supplies of downstream communities. Little is known about recent glacial-area changes and how the glaciers in this region respond to climate changes, and, ultimately, how these changes will affect lake and water supplies. To remedy this, we have used 158 multi-spectral satellite images spanning almost 4 decades, from 1975 to 2012, to obtain glacial- and lake-area outlines for the understudied Cordillera Vilcanota region, including the Quelccaya Ice Cap. Additionally, we have estimated the snow-line altitude of the Quelccaya Ice Cap using spectral unmixing methods. We have made the following four key observations: first, since 1988 glacial areas throughout the Cordillera Vilcanota (1988 glacial area: 361 km2) have been declining at a rate of 3.99 ± 1.15 km2 yr−1 (22 year average, 1988–2010, with 95% confidence interval (CI), n = 8 images). Since 1980, the Quelccaya Ice Cap (1980 glacial area: 63.1 km2) has been declining at a rate of 0.57 ± 0.10 km2 yr−1 (30 year average, 1980–2010, with 95% CI, n = 14). Second, decline rates for individual glacierized regions have been accelerating during the past decade (2000–2010) as compared to the preceding decade (1988–1999) with an average increase from 37.5 to 42.3 × 10−3 km2 yr−1 km−2 (13%). Third, glaciers with lower median elevations are declining at higher rates than those with higher median elevations. Specifically, glaciers with median elevations around 5200 m a.s.l. are retreating to higher elevations at a rate of ~1 m yr−1 faster than glaciers with median elevations around 5400 m a.s.l. Fourth, as glacial regions have decreased, 77% of lakes connected to glacial watersheds have either remained stable or shown a roughly synchronous increase in lake area, while 42% of lakes not connected to glacial watersheds have declined in area (58% have remained stable). Our new and detailed data on glacial and lake areas over 37 years provide an important spatiotemporal assessment of climate variability in this area. These data can be integrated into further studies to analyze inter-annual glacial and lake-area changes and assess hydrologic dependence and consequences for downstream populations.

scholarly journals Thinning of the Quelccaya Ice Cap over the last thirty years

2016 ◽  
Author(s):  
C. D. Chadwell ◽  
D. R. Hardy ◽  
C. Braun ◽  
H. H. Brecher ◽  
L. G. Thompson
Keyword(s):  
Unit Volume ◽  
Environmental Changes ◽  
Statistical Significance ◽  
Geophysical Methods ◽  
Snow Accumulation ◽  
Dual Frequency ◽  
The Past ◽  
Ice Cap ◽  
Ice Surface ◽  
Quelccaya Ice Cap

Abstract. Direct measurements of the decadal response of Tropical glaciers to environmental changes are difficult to acquire within their accumulation zones. In 2013, we used dual-frequency kinematic GPS to re-measure the surface elevations at 46 sites, from the margin to across the summit of the Quelccaya Ice Cap, first measured in 1983 using terrestrial surveying methods. In 2015, six additional sites on the western margin, first observed in 1978, were remeasured. Over the past 30 years, the ice cap summit has thinned by 4.41 ± 0.23 m (2σ), with a maximum ice loss at one site near the margin of 63.4 ± 0.34 m (2σ) over 37 years. Using geophysical methods that located the sub-glacial bedrock, we estimate the unit-volume of ice in 1983 along a profile from the 1983 margin to the summit and then the change in volume from 1983 to 2013 by differencing the surface elevations. Over the past 30 years, 21.2 ± 0.3 % (2σ) of the ice unit-volume has been lost suggesting an average annual mass balance rate of −0.5 ± 0.1 m w.e. a−1 (2σ). Increasing air temperature at high elevations of the Andes is likely a major driver of the observed changes. Specifically, within the ablation zone, thinning is likely caused by a 1–2 m w.e. a−1 increase in melting and sublimation above steady-state.Within the accumulation zone, analysis of annual, dry-season summit pits suggests that surface lowering may be caused by both a slight decrease in net snow accumulation and an increase in firnification rate, though this interpretation yet lacks statistical significance. The role of ice flux changes since 1983/4 remains unconstrained, awaiting updated measurements of ice surface velocities across the ice cap.

Subdivision of Glacial Deposits in Southeastern Peru Based on Pedogenic Development and Radiometric Ages

2001 ◽  
Vol 56 (1) ◽  
pp. 31-50 ◽  
Author(s):  
Adam Y. Goodman ◽  
Donald T. Rodbell ◽  
Geoffrey O. Seltzer ◽  
Bryan G. Mark
Keyword(s):  
Chemical Weathering ◽  
Late Quaternary ◽  
Laboratory Data ◽  
Ice Age ◽  
Tropical Andes ◽  
Southern Peru ◽  
Ice Cap ◽  
Quaternary Glaciation ◽  
Quelccaya Ice Cap ◽  
Age Estimates

AbstractThe Cordillera Vilcanota and Quelccaya Ice Cap region of southern Peru (13°30′–14°00′S; 70°40′–71°25′W) contains a detailed record of late Quaternary glaciation in the tropical Andes. Quantification of soil development on 19 moraine crests and radiocarbon ages are used to reconstruct the glacial history. Secondary iron and clay increase linearly in Quelccaya soils and clay accumulates at a linear rate in Vilcanota soils, which may reflect the semicontinuous addition of eolian dust enriched in secondary iron to all soils. In contrast, logarithmic rates of iron buildup in soils in the Cordillera Vilcanota reflect chemical weathering; high concentrations of secondary iron in Vilcanota tills may mask the role of eolian input to these soils. Soil-age estimates from extrapolation of field and laboratory data suggest that the most extensive late Quaternary glaciation occurred >70,000 yr B.P. This provides one of the first semiquantitative age estimates for maximum ice extent in southern Peru and is supported by a minimum-limiting age of ∼41,520 14C yr B.P. A late glacial readvance culminated ∼16,650 cal yr B.P. in the Cordillera Vilcanota. Following rapid deglaciation of unknown extent, an advance of the Quelccaya Ice Cap occurred between ∼13,090 and 12,800 cal yr B.P., which coincides approximately with the onset of the Younger Dryas cooling in the North Atlantic region. Moraines deposited <394 cal yr B.P. in the Cordillera Vilcanota and <300 cal yr B.P. on the west side of the Quelccaya Ice Cap correlate with Little Ice Age moraines of other regions.

Recently exposed vegetation reveals Holocene changes in the extent of the Quelccaya Ice Cap, Peru

2009 ◽  
Vol 72 (2) ◽  
pp. 157-163 ◽  
Author(s):  
Aron M. Buffen ◽  
Lonnie G. Thompson ◽  
Ellen Mosley-Thompson ◽  
Kyung In Huh
Keyword(s):  
Radiocarbon Dating ◽  
Sedimentary Sequence ◽  
Western Margin ◽  
The Past ◽  
Ice Cap ◽  
Plant Samples ◽  
Clastic Sedimentary ◽  
Quelccaya Ice Cap ◽  
Vegetation Samples

AbstractRadiocarbon dating of well-preserved, in-place vegetation exposed by the retreating Quelccaya Ice Cap of southeastern Peru constrains the last time the ice cap's extent was smaller than at present. Seventeen plant samples from two sites along the central western margin collectively date to 4700 and 5100 cal yr BP and strongly indicate that current ice cap retreat is unprecedented over the past ∼ 5 millennia. Seventeen vegetation samples interbedded in a nearby clastic sedimentary sequence suggest ice-free conditions at this site from ∼ 5200 to at least ∼ 7000 cal yr BP, and place minimum constraint on early- to mid-Holocene ice cap extent.

Similar Holocene glaciation histories in tropical South America and Africa

Geology ◽  
2020 ◽  
Author(s):  
Anthony C. Vickers ◽  
Jeremy D. Shakun ◽  
Brent M. Goehring ◽  
Andrew Gorin, ◽  
Meredith A. Kelly ◽  
...  
Keyword(s):  
South America ◽  
Large Scale ◽  
Past Century ◽  
Tropical Glaciers ◽  
The Past ◽  
Ice Cap ◽  
Ice Retreat ◽  
Quelccaya Ice Cap ◽  
The Tropics

Tropical glaciers have retreated alongside warming temperatures over the past century, yet the way in which these trends fit into a long-term geological context is largely unclear. Here, we present reconstructions of Holocene glacier extents relative to today from the Quelccaya ice cap (Peru) and the Rwenzori Mountains (Uganda) based on measurements of in situ14C and 10Be from recently exposed bedrock. Ice-extent histories are similar at both sites and suggest that ice was generally smaller than today during the first half of the Holocene and larger than today for most, if not all, of the past several millennia. The similar glaciation history in South America and Africa suggests that large-scale warming followed by cooling of the tropics during the late Holocene primarily drove ice extent, rather than regional changes in precipitation. Our results also imply that recent tropical ice retreat is anomalous in a multimillennial context.

Soziale Disziplinierung im flexiblen Kapitalismus

2004 ◽  
Vol 34 (136) ◽  
pp. 339-356
Author(s):  
Tobias Wölfle ◽  
Oliver Schöller
Keyword(s):  
Social Welfare ◽  
Second Step ◽  
Social Rights ◽  
Federal Law ◽  
Capitalist Development ◽  
The Core ◽  
The Past ◽  
The Impact ◽  
Municipal Level

Under the term “Hilfe zur Arbeit” (aid for work) the federal law of social welfare subsumes all kinds of labour disciplining instruments. First, the paper shows the historical connection of welfare and labour disciplining mechanisms in the context of different periods within capitalist development. In a second step, against the background of historical experiences, we will analyse the trends of “Hilfe zur Arbeit” during the past two decades. It will be shown that by the rise of unemployment, the impact of labour disciplining aspects of “Hilfe zur Arbeit” has increased both on the federal and on the municipal level. For this reason the leverage of the liberal paradigm would take place even in the core of social rights.

New forms of intra-European migration, labour market dynamics and social inequality in Europe

2014 ◽  
Vol 11 (2) ◽  
pp. 125-136 ◽  
Author(s):  
Roland Verwiebe ◽  
Laura Wiesböck ◽  
Roland Teitzer
Keyword(s):  
Labour Market ◽  
Social Inequality ◽  
Social Stratification ◽  
Labour Markets ◽  
Second Step ◽  
Market Dynamics ◽  
Migration Patterns ◽  
European Continent ◽  
The Past ◽  
European Migration

This article deals mainly with new forms of Intra-European migration, processes of integration and inequality, and the dynamics of emerging transnational labour markets in Europe. We discuss these issues against the background of fundamental changes which have been taking place on the European continent over the past two decades. Drawing on available comparative European data, we examine, in a first step, whether the changes in intra-European migration patterns have been accompanied by a differentiation of the causes of migration. In a second step, we discuss the extent to which new forms of transnational labour markets have been emerging within Europe and their effects on systems of social stratification.

scholarly journals Monitoring Changes in the Transparency of the Largest Reservoir in Eastern China in the Past Decade, 2013–2020

2021 ◽  
Vol 13 (13) ◽  
pp. 2570
Author(s):  
Teng Li ◽  
Bozhong Zhu ◽  
Fei Cao ◽  
Hao Sun ◽  
Xianqiang He ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Mean Squared Error ◽  
Eastern China ◽  
Water Environment ◽  
Relative Difference ◽  
Boreal Summer ◽  
Support Vector ◽  
Lake Area ◽  
The Past ◽  
Remote Sensing Reflectance

Based on characteristics analysis about remote sensing reflectance, the Secchi Disk Depth (SDD) in the Qiandao Lake was predicted from the Landsat8/OLI data, and its changing rates on a pixel-by-pixel scale were obtained from satellite remote sensing for the first time. Using 114 matchups data pairs during 2013–2019, the SDD satellite algorithms suitable for the Qiandao Lake were obtained through both the linear regression and machine learning (Support Vector Machine) methods, with remote sensing reflectance (Rrs) at different OLI bands and the ratio of Rrs (Band3) to Rrs (Band2) as model input parameters. Compared with field observations, the mean absolute relative difference and root mean squared error of satellite-derived SDD were within 20% and 1.3 m, respectively. Satellite-derived results revealed that SDD in the Qiandao Lake was high in boreal spring and winter, and reached the lowest in boreal summer, with the annual mean value of about 5 m. Spatially, high SDD was mainly concentrated in the southeast lake area (up to 13 m) close to the dam. The edge and runoff area of the lake were less transparent, with an SDD of less than 4 m. In the past decade (2013–2020), 5.32% of Qiandao Lake witnessed significant (p < 0.05) transparency change: 4.42% raised with a rate of about 0.11 m/year and 0.9% varied with a rate of about −0.09 m/year. Besides, the findings presented here suggested that heavy rainfall would have a continuous impact on the Qiandao Lake SDD. Our research could promote the applications of land observation satellites (such as the Landsat series) in water environment monitoring in inland reservoirs.

Creative geographies of Islam: the case of Islamic and traditional visual arts scene in Istanbul

2021 ◽  
pp. 147447402110536
Author(s):  
Hulya Arik
Keyword(s):  
Cultural Politics ◽  
Visual Arts ◽  
Urban Governance ◽  
Middle Eastern ◽  
Creative Industries ◽  
Limited Attention ◽  
The Past ◽  
Art Scene ◽  
Core Concepts ◽  
Early Republican

While research on geographies of creativity have proliferated in the last few years, there has been scant attention to religious cultural and artistic practices, particularly in the context of the Middle East. This research seeks to address such gap with a focus on the Islamic and traditional visual arts scene which has flourished in Istanbul in the past decade and a half along with the rise of political Islam in Turkey. Rendered obsolete through the Western-oriented and secular cultural politics since the early republican era, art forms such as Arabic calligraphy ( hat), miniature ( minyatür), and illumination ( tezhip) have now found currency as ‘authentically Turkish and Islamic’ in an art scene that emerged alongside Islamist politics. This paper examines the trajectory of Islamic and traditional visual arts through the lens of cultural and creative industries starting from the cultural politics of Islamic urban governance through the 1990s and 2000s, and to the emergence of an Islamist-nationalist authoritarianism in the past decade. In doing so, it aims to situate Islamic and traditional visual arts on the map in studies on geographies of creativity, particularly in the Middle Eastern and Islamic context, where limited attention has been paid to cultural and artistic practices. With ethnographic reflections from the field, it highlights the internal dynamics of an art scene and the potential it bears in unsettling the core concepts of Turkish Islamic nationalism from within.

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