Signals of 20th-century warming from the glaciers in the Central Italian Alps

The Lombard Alps in the central sector of the Italian Alps are one of the most intensively glacierized regions on the southern side of the chain (about 113 km2 of ice cover). All of the glaciers have been retreating since the beginning of the 20th century, but the trend is not uniform. Since the 1950s there has been a drop in the percentage of retreating snouts and an increase in stationary and advancing snouts. After 1985 the glaciers in the Lombard Alps began a new recession phase that is still going on. This pattern is consistent with temperature variations in Lombardy in the 20th century. According to data from Sondrio station, four alternating warming and cooling phases ran be distinguished in 20th-century warming. The Lombard glaciers well recorded the last three phases, showing evident signs of the 1955–88 cold phase, with a response time of about 20 years, and may be considered good indicators of 20th-century temperature trends

Dry calving processes at the ice cliff of Strandline Glacier northern Victoria Land, Antarctica

AbstractThis paper describes seasonal variations on Strandline Glacier, Terra Nova Bay, northern Victoria Land, Antarctica, obtained from measurements during two field campaigns (2000/01 and 2002/03). By applying different methodologies and techniques, it was possible to calculate summer changes in thickness (mean decrease over the whole glacier surface of 0.04 mw.e.) and in volume (decrease of 352 μ3 at the terminus). This serves to identify and quantify the processes responsible for these variations (e.g. melting, evaporation, wind erosion/deposition and calving) and to understand the energy transfers at the glacier–air interface. One particular feature of the glacier is the presence of an ice cliff at the terminus, which causes ablation owing to dry calving. This process brought about a summer retreat rate of 1 mweek–1 in the central part of the front during the study period. Qualitative observations carried out during previous field campaigns and quantitative analysis performed during the last two expeditions have provided an understanding of the mechanism underlying the ablation processes, thus confirming the available literature on this topic

Retreat of Mediterranean Glaciers since the Little Ice Age: Case Study of Ghiacciaio del Calderone, Central Apennines, Italy

Ghiacciaio del Calderone is the only glacier in the Italian Apennines and the southernmost glacier in Europe. In this paper, the authors present a tentative synthesis of the evolution of the glacier, with a particular focus on evaluating the variations in area and thickness ranging from the end of the Little Ice Age to the present. The analysis was performed in a GIS environment, using available data for georeferation (mainly from recent topographic maps) and for the reconstruction (from historical documents and old topographic maps) of the variations of the glacier in the last two centuries. The resulting values, reconstructed and/or calculated, covering the period since the end of the Little Ice Age, of about 36 m of ice thickness and of about 59,000 m2 of ice surface area represent the glacier loss by 1990

Glacier surface-area changes in Sagarmatha national park, Nepal, in the second half of the 20th century, by comparison of historical maps

AbstractWe investigate variations in the surface area of glaciers in Sagarmatha national park, Nepal, during the second half of the 20th century through comparison of a map applicable to the late 1950s with the official map of Nepal in the early 1990s. The comparison reveals a slight overall decrease in glacier area (by 4.9%, from 403.9 to 384.6 km2), a result which, though potentially subject to errors arising from cartographic interpretation, is in line with the area reductions found by other studies of Asian glaciers. We find that the areas of some individual glaciers, the largest situated at higher altitudes, increased during the study period. This was most apparent for the glaciers oriented to the south, with the increase occurring mainly in the glacier accumulation zones while the fronts tended to recede. Meanwhile, the smaller glaciers, situated lower and on steep basins, experienced a reduction. For the smaller glaciers, the sections most affected by change were the accumulation zones, and these glaciers showed a tendency for the front to advance. In this region there is a lack of climate data for high altitudes. Nevertheless, observations from stations situated around the park suggest that, alongside temperature variations which are often considered the primary factor eliciting glacier response, changes in precipitation play a significant role

Recent variations of Ghiacciaio del Calderone, Abruzzi, Italy

AbstractResults of a detailed topographic survey of Ghiacciaio del Calderone, Italy, the southernmost in Europe, are described and compared with those of surveys made in earlier years. Recession and thinning, much affected by micro-climate, have been the predominant state of health during the 20th century. Between 1916 and 1990, volume is estimated to have been reduced by about 90% and area by about 68%

Ice ablation and meteorological conditions on the debris-covered area of Baltoro glacier, Karakoram, Pakistan

AbstractDuring the recent Italian expedition 'K2 2004 – 50 years later' (June–July 2004) on Baltoro glacier, Karakoram, Pakistan, glaciological field experiments were carried out on the debris-covered area of this high-elevation glacier. The aim was to investigate the ice ablation and its relations with debris thermal properties and meteorological conditions. Ablation measurements along the glacier up to about 5000 m and within a dedicated test field were combined with meteorological data from two automatic weather stations located at Urdukas (4022 ma.s.l.) and at K2 Base Camp (5033 m a.s.l.). In addition, temperature measurements of the debris cover at different depth levels along the glacier allowed the calculation of debris surface temperature and of the debris thermal resistance (R). Using the air temperature, the local mean lapse rate (0.0075˚C m−1) and the measured ablation, the degree-day factors (K) at different locations on the glacier were calculated. The ice ablation rates were related to debris thickness and elevation. They are typically on the order of 4 cm d−1 during the observation period. However, it was found that the surface topography (slope, aspect) has an influence on the total ablation similar to that of the debris thickness. Thermal resistance of the debris cover and its distribution over the glacier were estimated. Finally, a best-guess estimate of the total meltwater production was calculated from available climate data

PRELIMINARY MAPPING OF GLACIERS AND GLACIAL LANDFORMS OF MOUNT AĞRI DAĞI (ARARAT), EASTERN ANATOLIA - TURKEY

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Yeast and yeast-like diversity in the southernmost glacier of Europe (Calderone Glacier, Apennines, Italy)

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An ablation model for debris-covered ice: the case study of Venerocolo Glacier (Italian Alps)

We developed a simple model to estimate ice ablation under a debris cover. The ablation process is modelled using energy and mass conservation equations for debris and ice and heat conduction, driven by input of either i) debris surface temperature or ii) radiation fluxes, and solved through a finite difference scheme computing the conductive heat flux within the supra-glacial debris layer. For model calibration, input and validation, we used approximately bi-weekly surveys of ice ablation rate, debris cover temperature, air temperature and solar incoming and upwelling radiation during for Summer 2007. We calibrated the model for debris thermal conductivity using a subset of ablation data and then we validated it using another subset. Comparisons between calculated and measured values showed a good agreement (RMSE = 0.04 m w.e., r = 0.79), thus suggesting a good performance of the model in predicting ice ablation. Thermal conductivity was found to be the most critical parameter in the proposed model, and it was estimated by debris temperature and thickness, with value changing along the investigated ablation season. The proposed model may be used to quantify buried ice ablation given a reasonable assessment of thermal conductivity