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.

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.

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.

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.

A LOOK INTO THE EARTH: EVALUATING THE USE OF MAGNETIC SURVEY IN AFRICAN ARCHAEOLOGY

2004 ◽  
Vol 2 (1) ◽  
pp. 49-63 ◽  
Author(s):  
Carlos Magnavita ◽  
Norbert Schleifer
Keyword(s):  
Geophysical Methods ◽  
Field Research ◽  
Archaeological Sites ◽  
Magnetic Survey ◽  
The Past ◽  
Common Technique ◽  
Sub Saharan ◽  
Prehistoric Settlements ◽  
Present Case Study

In the last decades, geophysical methods such as magnetic survey have become a common technique for prospecting archaeological sites. At sub-Saharan archaeological sites, however, magnetic survey and correlated techniques never came into broad use and there are no signs for an immediate change of this situation. This paper examines the magnetic survey undertaken on the Nigerian site of Zilum, a settlement of the Gajiganna Culture (ca 1800-400 BC) located in the Chad Basin and dated to ca 600-400 BC. By means of the present case study, we demonstrate the significance of this particular type of investigation in yielding complementary data for understanding the character of prehistoric settlements. In conclusion, we point out that geophysical methods should play a more important role in modern archaeological field research, as they furnish a class of documentation not achievable by traditional survey and excavation methods, thus creating new perspectives for interpreting the past of African societies.

scholarly journals Climate and environmental changes during the past millennium in central western Guizhou, China as recorded by Stalagmite ZJD-21

2011 ◽  
Vol 40 (6) ◽  
pp. 1111-1120 ◽  
Author(s):  
Tz-Shing Kuo ◽  
Zi-Qi Liu ◽  
Hong-Chun Li ◽  
Nai-Jung Wan ◽  
Chuan-Chou Shen ◽  
...  
Keyword(s):  
Environmental Changes ◽  
The Past ◽  
Western Guizhou ◽  
Past Millennium

Vegetational and environmental changes in the eastern Venetian coastal plain (Northern Italy) over the past 80,000 years

2007 ◽  
Vol 253 (3-4) ◽  
pp. 300-316 ◽  
Author(s):  
Giuseppe Canali ◽  
Luca Capraro ◽  
Sandra Donnici ◽  
Federica Rizzetto ◽  
Rossana Serandrei-Barbero ◽  
...  
Keyword(s):  
Coastal Plain ◽  
Environmental Changes ◽  
Northern Italy ◽  
The Past

Climate and environmental context of the Mongol invasion of Syria and defeat at ‘Ayn Jālūt (1258–1260 CE)

Erdkunde ◽  
2021 ◽  
Vol 75 (2) ◽  
pp. 87-104
Author(s):  
Nicola Di Cosmo ◽  
Sebastian Wagner ◽  
Ulf Büntgen
Keyword(s):  
Strategic Alliances ◽  
Turning Point ◽  
Environmental Changes ◽  
Environmental Variability ◽  
State Of The Art ◽  
Eastern Mediterranean ◽  
The Caucasus ◽  
Mountainous Regions ◽  
The Past ◽  
Climate Reconstructions

After a successful conquest of large parts of Syria in 1258 and 1259 CE, the Mongol army lost the battle of 'Ayn Jālūt against Mamluks on September 3, 1260 CE. Recognized as a turning point in world history, their sudden defeat triggered the reconfiguration of strategic alliances and geopolitical power not only in the Middle East, but also across much of Eurasia. Despite decades of research, scholars have not yet reached consensus over the causes of the Mongol reverse. Here, we revisit previous arguments in light of climate and environmental changes in the aftermath of one the largest volcanic forcings in the past 2500 years, the Samalas eruption ~1257 CE. Regional tree ring-based climate reconstructions and state-of-the-art Earth System Model simulations reveal cooler and wetter conditions from spring 1258 to autumn 1259 CE for the eastern Mediterranean/Arabian region. We therefore hypothesize that the post-Samalas climate anomaly and associated environmental variability affected an estimated 120,000 Mongol soldiers and up to half a million of their horses during the conquest. More specifically, we argue that colder and wetter climates in 1258 and 1259 CE, while complicating and slowing the campaign in certain areas, such as the mountainous regions in the Caucasus and Anatolia, also facilitated the assault on Syria between January and March 1260. A return to warmer and dryer conditions in the summer of 1260 CE, however, likely reduced the regional carrying capacity and may therefore have forced a mass withdrawal of the Mongols from the region that contributed to the Mamluks’ victory. In pointing to a distinct environmental dependency of the Mongols, we offer a new explanation of their defeat at 'Ayn Jālūt, which effectively halted the further expansion of the largest ever land-based empire.

scholarly journals Glaciological Investigations of the Tropical Quelccaya Ice Cap, Peru

1980 ◽  
Vol 25 (91) ◽  
pp. 69-84 ◽  
Author(s):  
Lonnie G. Thompson
Keyword(s):  
Rainy Season ◽  
Ice Core ◽  
Ice Cores ◽  
Dry Season ◽  
Radioactive Material ◽  
Polar Regions ◽  
Near Surface ◽  
Ice Cap ◽  
Activity Measurements ◽  
Quelccaya Ice Cap

AbstractGlaciological results of the continuing investigations of the Quelccaya ice cap located at lat. 13° 56’ S., long. 70° 50’ W., in the Cordillera Oriental of southern Peru are presented. Ice cores to a depth of 15 m have been retrieved from the summit dome (5650 m), middle dome (5543 m), and south dome (5480 m) and sampled in detail for microparticle, oxygen-isotope, and total-β-activity measurements. Results of these core analyses indicate that although the summit of this ice cap is only 300 m above the annual snow line and the firn is temperate, an interpretable stratigraphic record is preserved. The marked seasonal ice stratigraphy is produced by the marked seasonal variation in regional precipitation. High concentrations of microparticles and β- radioactive material occur during the dry season (May-August). Microparticles deposited during the rainy season are larger than those deposited during the dry season. On the Quelccaya ice cap the most negative δ18O values occur during the warmer rainy season (the opposite occurs in polar regions). The near-surface mean δ value of – 21‰ is remarkably low for this tropical site where the measured mean annual air temperature is – 3°C The seasonality of the microparticles, total β activity, and isotope ratios offers the prospect of a climatic ice-core record from this tropical ice cap.

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