Umberto Minora

A simple model to evaluate ice melt over the ablation area of glaciers in the Central Karakoram National Park, Pakistan

Abstract This study provides an estimate of fresh water derived from ice melt for the ablation areas of glaciers in the Central Karakoram National Park (CKNP), Pakistan. In the CKNP there are ~700 glaciers, covering ~4600 km2, with widespread debris cover (518 km2). To assess meltwater volume we applied a distributed model able to describe both debris-covered and debris-free ice ablation. The model was calibrated using data collected in the field in the CKNP area and validated by comparison with ablation data collected in the field, independent of the data used in building the model. During 23 July–9 August 2011, the mean model-estimated ablation in the CKNP was 0.024 m w.e. d–1 in debris-covered areas and 0.037 m w.e. d–1 in debris-free areas. We found a mean error of +0.01 m w.e. (corresponding to 2%) and a root-mean-square error equal to 0.09 m w.e. (17%). According to our model, the ablation areas of all the glaciers in the CKNP produced a water volume of 1.963 km3 during the study period. Finally, we performed several sensitivity tests for assessing the impact of the input data variations.

Light-dependent microbial metabolisms drive carbon fluxes on glacier surfaces.

Biological processes on glacier surfaces affect glacier reflectance, influence surface energy budget and glacier response to climate warming, and determine glacier carbon exchange with the atmosphere. Currently, carbon balance of supraglacial environment is assessed as the balance between the activity of oxygenic phototrophs and the respiration rate of heterotrophic organisms. Here we present a metagenomic analysis of tiny wind-blown supraglacial sediment (cryoconite) from Baltoro (Pakistani Karakoram) and Forni (Italian Alps) glaciers, providing evidence for the occurrence in these environments of different and previously neglected metabolic pathways. Indeed, we observed high abundance of heterotrophic anoxygenic phototrophs, suggesting that light might directly supplement the energy demand of some bacterial strains allowing them to use as carbon source organic molecules, which otherwise would be respired. Furthermore, data suggest that CO2 could be produced also by microbiologically mediated oxidation of CO, which may be produced by photodegradation of organic matter.

Glacier area stability in the Central Karakoram National Park (Pakistan) in 2001–2010 The “Karakoram Anomaly” in the spotlight

The Karakoram Range is one of the most glacierized mountain regions in the world, and glaciers there are an important water resource for Pakistan. The attention paid to this area is increasing because its glaciers remained rather stable in the early twenty-first century, in contrast to the general glacier retreat observed worldwide on average. This condition is also known as “Karakoram Anomaly”. Here we focus on the recent evolution of glaciers within the Central Karakoram National Park (CKNP, area: *13,000 km2) to assess their status in this region with respect to the described anomaly. A glacier inventory was produced for the years 2001 and 2010, using Landsat images. In total, 711 ice-bodies were detected and digitized, covering an area of 4605.9 ± 86.1 km2 in 2001 and 4606.3 ± 183.7 km2 in 2010, with abundant supraglacial debris cover. The difference between the area values of 2001 and 2010 is not significant (+0.4 ± 202.9 km2), confirming the anomalous behavior of glaciers in this region. The causes of such an anomaly may be various. The increase of snow cover areas from 2001 to 2011 detected using MODIS snow data; the reduction of mean summer temperatures; and the augmented snowfall events during 1980–2009 observed at meteorological stations and confirmed by the available literature, are climatic factors associated with positive mass balances. Because the response of glacier area change to climate variation is very slow for large glaciers, the presence of some of the largest glaciers of the Karakoram Range in this region might have delayed observed effects of such climate change so far, or alternatively, the change may not be sufficient to drive an actual area increase. In this context, improved understanding the role of debris cover, meltwater ponds, and exposed ice cliffs on debris-covered glaciers, and surging glaciers (which are also found abundant here), are required is still an issue to clarify the mechanisms behind the Karakoram Anomaly.

Temporal variability of bacterial communities in cryoconite on an alpine glacier

Cryoconite holes, that is, small ponds that form on glacier surface, are considered the most biologically active environments on glaciers. Bacterial communities in these environments have been extensively studied, but often through snapshot studies based on the assumption of a general stability of community structure. In this study, the temporal variation of bacterial communities in cryoconite holes on the Forni Glacier (Italian Alps) was investigated by high throughput DNA sequencing. A temporal change of bacterial communities was observed with autotrophic Cyanobacteria populations dominating communities after snowmelt, and heterotrophic Sphingobacteriales populations increasing in abundance later in the season. Bacterial communities also varied according to hole depth and area, amount of organic matter in the cryoconite and oxygen concentration. However, variation in environmental features explained a lower fraction of the variation in bacterial communities than temporal variation. Temporal change along ablation season seems therefore more important than local environmental conditions in shaping bacterial communities of cryoconite of the Forni Glacier. These findings challenge the assumption that bacterial communities of cryoconite holes are stable.

Potential sources of bacteria colonizing the cryoconite of an Alpine glacier

We investigated the potential contribution of ice-marginal environments to the microbial communities of cryoconite holes, small depressions filled with meltwater that form on the surface of Forni Glacier (Italian Alps). Cryoconite holes are considered the most biologically active environments on glaciers. Bacteria can colonize these environments by short-range transport from ice-marginal environments or by long-range transport from distant areas. We used high throughput DNA sequencing to identify Operational Taxonomic Units (OTUs) present in cryoconite holes and three ice-marginal environments, the moraines, the glacier forefield, and a large (> 3 m high) ice-cored dirt cone occurring on the glacier surface. Bacterial communities of cryoconite holes were different from those of ice-marginal environments and hosted fewer OTUs. However, a network analysis revealed that the cryoconite holes shared more OTUs with the moraines and the dirt cone than with the glacier forefield. Ice-marginal environments may therefore act as sources of bacteria for cryoconite holes, but differences in environmental conditions limit the number of bacterial strains that may survive in them. At the same time, cryoconite holes host a few OTUs that were not found in any ice-marginal environment we sampled, thus suggesting that some bacterial populations are positively selected by the specific environmental conditions of the cryoconite holes.

Inventory of glaciers and glacial lakes of the Central Karakoram National Park (CKNP – Pakistan)

ABSTRACT This study presents a map reporting valuable information on the cryosphere of the Central Karakoram National Park (CKNP, the largest protected area of Pakistan and the highest park in the world). All the information is provided considering the CKNP as a whole, and in detail by dividing it into five basins (i.e. Shigar, Hunza, Shyok, Upper Indus, and Gilgit). The glacier inventory reports 608 ice bodies covering 3680 km2 (∼35% of the CKNP area), with a total glacier volume of ca. 532 km3. In addition, we modeled the meltwater from glacier ice ablation over the period 23 July to 9 August 2011. The total melt amount is ca. 1.5 km3. Finally, we considered glacial lakes (202 water-bodies, covering 4 km2). For these latter glacier features, we also analyzed their potentially dangerous conditions and two lakes were found having such conditions.

Bacterial diversity in snow from mid-latitude mountain areas: Alps, Eastern Anatolia, Karakoram and Himalaya

ABSTRACT Snow can be considered an independent ecosystem that hosts active microbial communities. Snow microbial communities have been extensively investigated in the Arctic and in the Antarctica, but rarely in mid-latitude mountain areas. In this study, we investigated the bacterial communities of snow collected in four glacierized areas (Alps, Eastern Anatolia, Karakoram and Himalaya) by high-throughput DNA sequencing. We also investigated the origin of the air masses that produced the sampled snowfalls by reconstructing back-trajectories. A standardized approach was applied to all the analyses in order to ease comparison among different communities and geographical areas. The bacterial communities hosted from 25 to 211 Operational Taxonomic Units (OTUs), and their structure differed significantly between geographical areas. This suggests that snow bacterial communities may largely derive from ‘local’ air bacteria, maybe by deposition of airborne particulate of local origin that occurs during snowfall. However, some evidences suggest that a contribution of bacteria collected during air mass uplift to snow communities cannot be excluded, particularly when the air mass that originated the snow event is particularly rich in dust.