• Energy Research

AbstractAbramov glacier, located in the Pamir Alay, Kyrgyzstan, is a reference glacier within the Global Terrestrial Network for Glaciers. Long-term glaciological measurements exist from 1968 to 1998 and a mass-balance monitoring programme was re-established in 2011. In this study we re-analyse existing mass-balance data and use a spatially distributed mass-balance model to provide continuous seasonal time series of glacier mass balance covering the period 1968–2014. The model is calibrated to seasonal mass-balance surveys and then applied to the period with no measurements. Validation and recalibration is carried out using snowline observations derived from satellite imagery and, after 2011, also from automatic terrestrial camera images. We combine direct measurements, remote observations and modelling. The results are compared to geodetic glacier volume change over the past decade and to a ground-penetrating radar survey in the accumulation zone resolving several layers of accumulation. Previously published geodetic mass budget estimates for Abramov glacier suggest a close-to-zero mass balance for the past decade, which contradicts our results. We find a low plausibility for equilibrium conditions over the past 15 years. Instead, we suggest that the glacier’s sensitivity to increased summer air temperature is decisive for the substantial mass loss during the past decade.

High elevation or high latitude hydropower production (HP) strongly relies on water resources that are influenced by glacier melt and are thus highly sensitive to climate warming. Despite of the wide-spread glacier retreat since the development of HP infrastructure in the 20th century, little quantitative information is available about the role of glacier mass loss for HP. We provide the first regional quantification for the share of Alpine hydropower production that directly relies on the waters released by glacier mass loss, i.e. on depletion of long-term ice storage that cannot be replenished by precipitation in the coming decades. Based on the case of Switzerland (which produces over 50% of its electricity from hydropower), we show that since 1980, 3.0% to 4.0% (1.0 to 1.4 TWh yr-1) of the country-scale hydropower production was directly provided by the net glacier mass loss and that this share is likely to reduce substantially by 2040-2060. For the period 2070-2090, a production reduction of about 1.0 TWh yr-1 is anticipated. The highlighted regional differences, both in terms of HP share from glacier mass loss and in terms of timing of production decline, emphasize the need for similar analyses in other Alpine or high latitude regions.

The anticipated retreat of glaciers around the globe will pose far-reaching challenges to the management of fresh water resources and significantly contribute to sea-level rise within the coming decades. Here, we present a new model for calculating the twenty-first century mass changes of all glaciers on Earth outside the ice sheets. The Global Glacier Evolution Model (GloGEM) includes mass loss due to frontal ablation at marine-terminating glacier fronts and accounts for glacier advance/retreat and surface elevation changes. Simulations are driven with monthly near-surface air temperature and precipitation from 14 Global Circulation Models forced by RCP2.6, RCP4.5, and RCP8.5 emission scenarios. Depending on the scenario, the model yields a global glacier volume loss of 25–48% between 2010 and 2100. For calculating glacier contribution to sea-level rise, we account for ice located below sea-level presently displacing ocean water. This effect reduces the glacier contribution by 11–14%, so that our model predicts a sea-level equivalent (multi-model mean ±1 standard deviation) of 79±24 mm (RCP2.6), 108±28 mm (RCP4.5), and 157±31 mm (RCP8.5). Mass losses by frontal ablation account for 10% of total ablation globally, and up to ~30% regionally. Regional equilibrium line altitudes are projected to rise by ~100–800 m until 2100, but the effect on ice wastage depends on initial glacier hypsometries. Frontiers in Earth Science, 3 ISSN:2296-6463

Ice-marginal moraines are widely used as indicators of palaeoclimate in mountainous regions, yet the genetic processes of their formation remain incompletely understood. Here, we present new data on the geomorphology and sedimentology of annually formed moraine ridges in the foreland of Gornergletscher, Switzerland, with the aim of reconstructing the processes of their formation, assessing their preservation potential over longer time scales, and evaluating the climatic significance of these terrestrial archives. A specific focus is set on moraine ridges that formed between 2007 and 2019, a period when the glacier front was subject to pronounced retreat and thinning. Four dominant mechanisms of moraine formation could be identified to be operating across the foreland: (I) freeze-on of submarginal sediments to the advancing glacier sole; (II) the formation of ice-cored moraines controlled by the emergence of englacial debris bands on the glacier surface; (III) efficient bulldozing and deformation of pre-existing fluvial or lacustrine sediments by the advancing glacier; and (IV) inefficient bulldozing of these deposits with the incorporation of dead ice into moraine bodies. The spatial distribution of these processes in the foreland depends on a set of climatological, topographical, and glaciological boundary conditions, the most important of which appears to be the slope of the ice margin. The largest and most well-defined moraines can be genetically linked to efficient bulldozing operating along a sufficiently steep glacier front. These moraines frequently form parts of longer, continuous chains and can be used to calculate frontal retreat rates of the glacier through time. Comparing this record of ice retreat with climatic data reveals a statistically significant correlation to annual air temperature anomalies, which is especially strong for the period between 2005 and 2017. Longer series of annual moraines may therefore provide important information about the climatic drivers that govern glacier retreat. However, dead ice is often found to be incorporated into moraine bodies along the present, thin ice margin. Upon melt-out of the ice, the morphologies and internal structures of these moraines are strongly altered, thus limiting their preservation potential over longer timescales. In such a scenario, the morphological record remaining in a deglaciated landscape may be incomplete or entirely lacking. Therefore, we conclude that great care must be taken when interpreting moraine sequences in a palaeoclimatic context. Quaternary Science Reviews, 308 ISSN:0277-3791

AbstractDue to climate change, worldwide glaciers are rapidly declining. The trend will continue into the future, with consequences for sea level, water availability and tourism. Here, we assess the future evolution of all glaciers in Scandinavia and Iceland until 2100 using the coupled surface mass-balance ice-flow model GloGEMflow. The model is initialised with three distinct past climate data products (E-OBS, ERA-I, ERA-5), while future climate is prescribed by both global and regional climate models (GCMs and RCMs), in order to analyze their impact on glacier evolution. By 2100, we project Scandinavian glaciers to lose between 67 ± 18% and 90 ± 7% of their present-day (2018) volume under a low (RCP2.6) and a high (RCP8.5) emission scenario, respectively. Over the same period, losses for Icelandic glaciers are projected to be between 43 ± 11% (RCP2.6) and 85 ± 7% (RCP8.5). The projected evolution is only little impacted by both the choice of climate data products used in the past and the spatial resolution of the future climate projections, with differences in the ice volume remaining by 2100 of 7 and 5%, respectively. This small sensitivity is attributed to our model calibration strategy that relies on observed glacier-specific mass balances and thus compensates for differences between climate forcing products.