ACCELERATING CLIMATE CHANGE IMPACTS ON ALPINE GLACIER FOREFIELD ECOSYSTEMS IN THE EUROPEAN ALPS

In the European Alps the increase in air temperature was more than twice the increase in global mean temperature over the last 50 years. The abiotic ( glacial) and the biotic components ( plants and vegetation) of the mountain environment are showing ample evidence of climate change impacts. In the Alps most small glaciers (80% of total glacial coverage and an important contribution to water resources) could disappear in the next decades. Recently climate change was demonstrated to affect higher levels of ecological systems, with vegetation exhibiting surface area changes, indicating that alpine and nival vegetation may be able to respond in a fast and flexible way in response to 1-2 degrees C warming. We analyzed the glacier evolution ( terminus fluctuations, mass balances, surface area variations), local climate, and vegetation succession on the forefield of Sforzellina Glacier ( Upper Valtellina, central Italian Alps) over the past three decades. We aimed to quantify the impacts of climate change on coupled biotic and abiotic components of high alpine ecosystems, to verify if an acceleration was occurring on them during the last decade (i.e., 1996-2006) and to assess whether new specific strategies were adopted for plant colonization and development. All the glaciological data indicate that a glacial retreat and shrinkage occurred and was much stronger after 2002 than during the last 35 years. Vegetation started to colonize surfaces deglaciated for only one year, with a rate at least four times greater than that reported in the literature for the establishment of scattered individuals and about two times greater for the well-established discontinuous early-successional community. The colonization strategy changed: the first colonizers are early-successional, scree slopes, and perennial clonal species with high phenotypic plasticity rather than pioneer and snowbed species. This impressive acceleration coincided with only slight local summer warming ( approximately +0.5 degrees C) and a poorly documented local decrease in the snow cover depth and duration. Are we facing accelerated ecological responses to climatic changes and/or did we go beyond a threshold over which major ecosystem changes may occur in response to even minor climatic variations?

Preliminary results from antarctic albedo from remote sensing observations

The aim of the study is to analyse the surface albedo of the Ant-arctica and investigate eventual signals of variations in space and time between summer 2000/2001 and 2011/2012 by means of the GLASS albedo product. We followed a step-by-step procedure from micro- to macro-scale. At first, we analysed 95 glaciers around the continent, and we found limited temporal variability. Then, looking at spatial varia-tions, we divided Antarctica based on oceanic basins and by continen-tality. We found spatial signals, since mean albedo values range between 0.79 (Pacific and Atlantic basins) and 0.82 (Indian basin) and between 0.76 (along the shore) and 0.81 (inner continent). An increasing vari-ability was found from the inner continent to the shore, and heteroge-neous patterns among the basins, most likely due to meteorological and environmental conditions (mainly: temperature, precipitation, katabatic winds). Finally, the general patterns observed (considering the specific gla-ciers, the three basins and the three continentality sectors) were verified by the analysis of the whole continent and we did not find a significant change of summer averages over time, as they range between 0.79 and 0.80

Distribution of the surface energy budget: Preliminary analysis on the incoming solar radiation. the case study of the Forni Glacier (Italy)

This study represents a contribution to distribution of the surface energy budget of the Forni Glacier (Ortles-Cevedale Group, Upper Valtellina, Italy). The analyses are based on data acquired at S. Caterina Valfurva (a village in the glacier valley at 1768 m ellipsoidal elevation WGS84) by an Automatic Weather Station (AWS) installed and managed by the Lombardy Agency for the Environment ("ARPA Lombardia"). We focus on the two most important meteorological parameters affecting surface energy budget: air temperature (T) and incoming shortwave radiation (SWin). Data collected from the ARPA AWS are used to evaluate these parameters at the glacier surface during the meteorological summer 2009 (from 1st June to 31st August 2009) and then the computations are validated through comparison with data recorded by an AWS installed at the surface of Forni Glacier tongue ("AWS1 Forni", 2669 m ellipsoidal elevation WGS84). The analysis of the distributed air temperature data enabled identification of the lowest value (-11.9 degrees C), found at the Mount S. Matteo peak (3669 m) on 22nd June at 8: 00 pm, and the highest value (+16.1 degrees C), recorded at the glacier terminus (2497 m) on 23 rd July at 2: 00 pm. The seasonal temperature amplitude (Tmax-Tmin) was 28 degrees C. The hottest week was 20th-26th July 2009 and the coldest was 1st-7th June 2009. Regarding daily SWin distribution, the maximum value (406.9 Wm(-2)) was recorded on 13th June and the minimum (28.5 Wm(-2)) on 6th June. From the analysis of hourly SWin values we could distinguish between days with clear sky conditions and days with intense cloud cover. Weekly mean SWin data showed the greatest value (327.1 Wm(-2)) from 20th-26th July 2009 and the lowest (207.8 Wm(-2)) from 22nd-28th June 2009. Furthermore, in analysing SWin it is critical to take into account the problem of shading. Using the Hillshade tool of ArcGIS, which takes into account only the slope and the aspect of each grid cell neglecting the surrounding topography effect, we compiled 66 shadow maps. Finally this study represents a first approach in modelling the distributed incoming solar radiation. In fact the considered driving factors are the elevation, the slope and the aspect of each grid cell. The next step will consist in taking into account the surrounding topography and the actual atmosphere conditions as well

Glaciological characteristics of the ablation zone of Baltoro glacier, Karakoram, Pakistan

AbstractBaltoro glacier in the Karakoram, Pakistan, is one of the world's largest valley glaciers. It drains an area of about 1500 km2 and is >60km long. In 2004 an Italian/German expedition carried out a glaciological field program on the ablation zone of the glacier, focusing on the ablation conditions and the dynamic state of the glacier. As Baltoro glacier is a debris-covered glacier, ice ablation also depends on the debris properties. Stake measurements of ice ablation and debris cover in combination with meteorological data from automatic weather stations close by have been used to determine the local melt conditions. Results from these calculations have been combined with an analysis of different classes of surface cover and information about precipitation, using remote-sensing techniques, in order to calculate mass fluxes for the upper part of Baltoro glacier. The dynamic state of the glacier has been investigated by GPS-based surface velocity measurements along the stake network. A comparison of these short-term measurements during the melt season with surface velocities computed from feature tracking of satellite images shows a high seasonal variability of the ice motion. We have shown that this variability is up to 100% of the annual mean velocity. On the basis of these investigations, the mass fluxes at the Concordia cross-section have been quantified. This approach can now be used together with the ablation calculations to reconstruct the variability of glacier extent and volume in the past using available climate data from the central Karakoram. From the comparison of historical measurements and photographs it is shown that the snout of Baltoro glacier is oscillating back and forth a couple of hundred metres. Otherwise it seems not to react with the same magnitude as other glaciers to the climatic change. Elevation changes at Concordia are a few tens of metres at the most

I Ghiacciai della Val Sissone (Valtellina, Alpi Retiche) e la loro storia olocenica

La ricostruzione dell\u2019evoluzione di alcuni ghiacciai della Val Sissone (Alpi Retiche), in particolare quello del Disgrazia, ha permesso di fornire un contributo alla conoscenza delle fluttuazioni glaciali alpine con particolare riguardo alla Piccola Et\ue0 Glaciale ed ai periodi pi\uf9 recenti. Attraverso l\u2019utilizzo di diversi metodi di datazione (radiocarbonio, dendrogeomorfologia, documentazione storica), la massima espansione olocenica dell\u2019apparato glaciale del Disgrazia dovrebbe collocarsi dopo il XIV secolo, con altre espansioni negli anni \u201920-\u201830 o negli anni \u201950 del XIX secolo ed infine negli anni \u201920 e \u201980 del XX secolo. La tendenza del XX secolo, documentata da misure dirette delle variazioni frontali, \ue8 stata in ogni caso nettamente negativa e ha portato la fronte del Disgrazia ad arretrare di circa 1 km.The reconstruction of the evolution of some Val Sissone glaciers (Rhetian Alps, Italy), with particular attention to the Disgrazia Glacier, gives a contribution to the knowledge of the glacial fluctuations since the Little Ice Age in the Italian Alps. By utilizing different dating methods (radiocarbon, dendrogeomorphology, historical documentation), it is possible to attribute the maximum glacial advance to a period after the XIX Century. Other glacier expansion phases belong to the '20 yrs of the XIX Century and to the '20 and '80 years of the XX Century. The XX Century trend, based on terminus variation direct measurements, was in any case absolutely negative and caused a retreat of the Disgrazia Glacier snout of about 1 k

Modelling hydrological components of the Rio Maipo of Chile, and their prospective evolution under climate change

We used the Poly-Hydro model to assess the main hydrological components of the snow-ice melt driven Maipo River in Chile, and glaciers' retreat under climate change therein until 2100. We used field data of ice ablation, ice thickness, weather and hydrological data, and precipitation from TRMM. Snow cover and temperature were taken from MODIS. We forced the model using weather projections until 2100 from three GCMs from the IPCC AR5, under three different radiative concentration pathways (RCPs 2.6, 4.5, 8.5). We investigated trends of precipitation, temperature, and hydrology until 2100 in the projection period (PR, 2014-2100) and the whole period (CM 1980-2100, composite), against historical trends in control period (CP, 1980-2013). We found potentially increasing temperature until 2100, except for Spring (OND). In the PR period, yearly flow decreases significantly under RCP85, on average -0.25 m 3 \ub7s -1 \ub7year -1 , and down to -0.48 m 3 \ub7s -1 \ub7year -1 , i.e., -0.4% year -1 against CP yearly average (120 m 3 s -1 ). In the long run (CM) significant flow decrease would, occur under almost all scenarios, confirming persistence of a historical decrease, down to -0.39 m 3 \ub7s -1 \ub7year -1 during CM. Large flow decreases are expected under all scenarios in Summer (JFM) during PR, down to -1.6 m 3 \ub7s -1 \ub7year -1 , or -1% year -1 against CP for RCP8.5, due to increase of evapotranspiration in response to higher temperatures. Fall (AMJ) flows would be mostly unchanged, whileWinter (JAS) flows would be projected to increase significantly, up to 0.7 m 3 \ub7s -1 \ub7year -1 during 2014-2100, i.e., +0.9% year -1 vs. CP under RCP8.5, due to large melting therein. Spring (OND) flows would decrease largely under RCP8.5, down to -0.67 m 3 s -1 \ub7year -1 , or -0.4% year -1 vs. CP, again due to evapotranspiration. Glacier down wasting is projected to speed up, and increasingly so with RCPs. Until 2100 ice loss would range from -13% to -49% (-9%, and -39% at 2050) of the estimated volume at 2012, which changed by -24% to -56% (-21%, and -39% at 2050) vs. ice volume in 1982, thus with rapider depletion in the first half of the century. Policy makers will have to cope with modified hydrological cycle in the Maipo River, and greatly decreasing ice cover in the area

An investigation of the influence of supraglacial debris on glacier-hydrology

Abstract. The influence of supraglacial debris on the rate and spatial distribution of glacier surface melt is well established, but its potential impact on the structure and evolution of the drainage system of extensively debris-covered glaciers has not been previously investigated. Forty-eight dye injections were conducted on Miage Glacier, Italian Alps, throughout the 2010 and 2011 ablation seasons. An efficient conduit system emanates from moulins in the mid-part of the glacier, which are downstream of a high melt area of dirty ice and patchy debris. High melt rates and runoff concentration by intermoraine troughs encourages the early-season development of a channelized system downstream of this area. Conversely, the drainage system beneath the continuously debris-covered lower ablation area is generally inefficient, with multi-peaked traces suggesting a distributed network, which likely feeds into the conduit system fed by the upglacier moulins. Drainage efficiency from the debris-covered area increased over the season but trace flow velocity remained lower than from the upper glacier moulins. Low and less-peaked melt inputs combined with the hummocky topography of the debris-covered area inhibits the formation of an efficient drainage network. These findings are relevant to regions with extensive glacial debris cover and where debris cover is expanding.</jats:p

The impact of supraglacial debris on proglacial runoff and water chemistry

Debris is known to influence the ablation, topography and hydrological systems of glaciers. This paper determines for the first time how these influences impact on bulk water routing and the proglacial runoff signal, using analyses of supraglacial and proglacial water chemistry and proglacial discharge at Miage Glacier, Italian Alps. Debris does influence the supraglacial water chemistry, but the inefficient subglacial system beneath the debris-covered zone also plays a role in increasing the ion contribution to the proglacial stream. Daily hydrographs had a lower amplitude and later discharge peak compared to clean glaciers and fewer diurnal hydrographs were found compared to similar analysis for Haut Glacier d’Arolla. We attribute these observations to the attenuating effect of the debris on ablation, smaller input streams on the debris-covered area, a less efficient subglacial system, and possible leakage into a raised sediment bed beneath the glacier. Strongly diurnal hydrographs are constrained to periods with warmer than average conditions. ‘Average’ weather conditions result in a hydrograph with reverse asymmetry. Conductivity and discharge commonly show anti-clockwise hysteresis, suggesting the more dilute, rapidly-routed melt component from the mid-glacier peaks before the discharge peak, with components from higher up-glacier and the debris-covered areas arriving later at the proglacial stream. The results of this study could lead to a greater understanding of the hydrological structure of other debris-covered glaciers, with findings highlighting the need to include the influence of the debris cover within future models of debris-covered glacier runoff

2008-2011 snow covered area (SCA) variability over 18 watersheds of the central Chile through MODIS data

Snowmelt contributes largely to water budget of several Chilean mountain watersheds. To describe snow covered area (SCA) variability within 18 watersheds in Central Chile during 2008\u20132011 we used MODIS data (i.e. MOD10A2-V5 maximum snow cover extent in eight-day periods). The study area was divided into three different zones (Northern, Central, and Southern), due to its large extent (~205,000 km2), and according to former studies performed by the Direcc\uedon General de Aguas (DGA) of the Chilean Government covering the time window 2000\u20132007. After georeferencing our data to the WGS84 Datum (UTM Projection, zone 19S), the scenes were cropped to fit the study area. We selected and set a threshold for cloud coverage (<30%) in order to discard the images with too cloud cover, so losing only 2% of the sample. Hypsographic and aspect analyses were performed using the SRTM3 elevation model. We found largest values of SCA during 2008\u20132011 in the Central Zone, while the topographic and climatic features (i.e. lower altitudes in the South, and a drier climate in the North) limit snow deposition elsewhere. Similarly, snow line is higher in the Northern zone (due to the presence of the plateau), and lower moving southwards. In the North the minimum SCA is reached sooner than elsewhere, lasting for a longer period (November to March). West side showed the maximum of SCA in all zones throughout the study period. The present work extends in time the dataset of SCA in the Central Chile, adding information for statistic assessment, and trend analysis of snow cover in this area

Prediction of future hydrological regimes in poorly gauged high altitude basins: the case study of the upper Indus, Pakistan

In the mountain regions of the Hindu Kush, Karakoram and Himalaya (HKH) the "third polar ice cap" of our planet, glaciers play the role of "water towers" by providing significant amount of melt water, especially in the dry season, essential for agriculture, drinking purposes, and hydropower production. Recently, most glaciers in the HKH have been retreating and losing mass, mainly due to significant regional warming, thus calling for assessment of future water resources availability for populations down slope. However, hydrology of these high altitude catchments is poorly studied and little understood. Most such catchments are poorly gauged, thus posing major issues in flow prediction therein, and representing in fact typical grounds of application of PUB concepts, where simple and portable hydrological modeling based upon scarce data amount is necessary for water budget estimation, and prediction under climate change conditions. In this preliminarily study, future (2060) hydrological flows in a particular watershed (Shigar river at Shigar, ca. 7000 km&lt;sup&gt;2&lt;/sup&gt;), nested within the upper Indus basin and fed by seasonal melt from major glaciers, are investigated. &lt;br&gt;&lt;br&gt; The study is carried out under the umbrella of the SHARE-Paprika project, aiming at evaluating the impact of climate change upon hydrology of the upper Indus river. We set up a minimal hydrological model, tuned against a short series of observed ground climatic data from a number of stations in the area, in situ measured ice ablation data, and remotely sensed snow cover data. The future, locally adjusted, precipitation and temperature fields for the reference decade 2050–2059 from &lt;i&gt;CCSM3&lt;/i&gt; model, available within the IPCC's panel, are then fed to the hydrological model. We adopt four different glaciers' cover scenarios, to test sensitivity to decreased glacierized areas. The projected flow duration curves, and some selected flow descriptors are evaluated. The uncertainty of the results is then addressed, and use of the model for nearby catchments discussed. The proposed approach is valuable as a tool to investigate the hydrology of poorly gauged high altitude areas, and to project forward their hydrological behavior pending climate change