The dynamics of seasonal snow ablation on six glaciers in central Spitsbergen (Dicksonland) were assessed by examining a set of Sentinel-2 satellite images covering the summer ablation season for the ...period 2016–19. All glaciers lost 80% or more of their surface snow cover during the studied ablation seasons. This bolsters the recently observed trend of local glacier thinning, even at higher altitudes. Snow ablation dynamics are highly dependent on the glaciers altitudes, their position relative to the prevailing wind direction and the exposure to insolation. The accumulation areas of the studied glaciers were delimited based on the overlap of the minimum extent of snow-covered areas in the four consecutive studied summer seasons. The high temporal and spatial resolutions of available images enabled a detailed description of the seasonal snow ablation dynamics. Moreover, an estimate of the average number of days with below threshold glacier snow cover was made. This study contributes to our understanding of recent processes and might further support the modelling of glacier melt and subsequent runoff.
The retreat rates of Triangular Glacier since 1979 and its mass changes during the period 2014/15–2019/20 indicate the sensitive response of small ice masses on the eastern side of the Antarctic ...Peninsula to air temperature evolution. This cirque glacier in the northern part of James Ross Island receded rapidly during the period of regional warming in the late 20th century, losing 30.8% of its surface area between 1979 and 2006 (−1.7% a−1). The retreat rate then dropped to −0.3% a−1 following the regional cooling trend, but started to accelerate again (−0.8 to −2.3% a−1) with increasing air temperature since the summer 2014/15. Since the glaciological year 2015/16, Triangular Glacier has experienced enhanced snow melt, wind scour and permanent mass loss with annual mass balance ranging from −0.08 ± 0.35 to −0.56 ± 0.25 m w.e. The largest mass loss was observed in the glaciological year 2019/20, which included the warmest summer of the observation period. The cumulative mass balance of −1.66 ± 0.83 m w.e. over the years 2014/15–2019/20 is consistent with the termination of the positive mass-balance period that occurred in the north-eastern Antarctic Peninsula from 2009/10 to 2014/15.
Abstract
Svalbard has experienced a dramatic increase in air temperature and glacier retreat since the end of the Little Ice Age. In many cases, this retreat has resulted in glaciers transitioning ...from being marine-terminating to land-terminating. Nordenskiöldbreen is an excellent contemporary example of this transition. A set of historical observations of glacier front positions was used to assess Nordenskiöldbreen's retreat rate and we found that the southern portion of the glacier front retreated by ~3500 m, since records began in 1896. The general retreat rate corresponds well with the air temperature trend during most of the 20th century. However, the average retreat rate has slowed since the 1990s despite increasing air temperatures. We show that this discrepancy between air temperature and retreat rate marks the transition from marine-terminating towards a land-terminating glacier, as the glacier's bedrock topography started to play an essential role in the glacier margin geometry, ice flow and retreat dynamics.
Abstract Glaciers cover 132 900 km 2 around the Antarctic Ice Sheet, but few are subject to annual mass-balance measurements. Lookalike Glacier and Davies Dome on James Ross Island have been ...monitored since 2009, providing the third longest mass-balance record for the northern Antarctic Peninsula. These glaciers had a balanced mass budget over the period 2009/10–2014/15 but started to lose their mass thereafter. Between 2014/15 and 2020/21, mass change rates were −0.15 ± 0.13 and −0.26 ± 0.11 m w.e. a −1 for Lookalike Glacier and Davies Dome, respectively. The mean equilibrium-line altitudes over this period at Lookalike Glacier (362 ± 18 m a.s.l.) and Davies Dome (>427 ± 22 m a.s.l.) are 51 and >34 m higher compared to the previous 6-year period. The mean accumulation area ratio values determined for the period 2014/15–2020/21 are lower than the balanced-budget ratio indicating that glaciers are out of balance with the current climate. The data confirm the transition from positive to negative mass-balance periods around 2014/15, which is attributed to the change in air temperature trends. The mean summer temperature increased by 0.9°C between the periods 2009/10–2014/15 and 2015/16–2020/21 and melt-season temperatures became predominantly positive.
Tidewater glaciers on the east coast of Svalbard were examined for surface elevation changes and retreat rate. An archival digital elevation model (DEM) from 1970 (generated from aerial images by the ...Norwegian Polar Institute) in combination with recent ArcticDEM were used to compare the surface elevation changes of eleven glaciers. This approach was complemented by a retreat rate estimation based on the analysis of Landsat and Sentinel-2 images. In total, four of the 11 tidewater glaciers became land-based due to the retreat of their termini. The remaining tidewater glaciers retreated at an average annual retreat rate of 48 m year−1, and with range between 10–150 m year−1. All the glaciers studied experienced thinning in their frontal zones with maximum surface elevation loss exceeding 100 m in the ablation areas of three glaciers. In contrast to the massive retreat and thinning of the frontal zones, a minor increase in ice thickness was recorded in some accumulation areas of the glaciers, exceeding 10 m on three glaciers. The change in glacier geometry suggests an important shift in glacier dynamics over the last 50 years, which very likely reflects the overall trend of increasing air temperatures. Such changes in glacier geometry are common at surging glaciers in their quiescent phase. Surging was detected on two glaciers studied, and was documented by the glacier front readvance and massive surface thinning in high elevated areas.
With the ongoing climate change and the prolongation of the summer melting season and increasing air temperature that this entails, fluvial transport is likely to become a more important process ...shaping the deglaciated areas of Antarctica. Quantification of suspended sediment transport in the deglaciated catchment of the Bohemian Stream is presented in this study. It was shown that a large amount of fine-grained material is being transported even in the relatively small catchment during the short period of the Antarctic summer. The average calculated suspended sediment concentration during the 2018 austral summer reached 274.6 mg l
−1
, which corresponded to an average suspended sediment load of 3662 kg day
−1
and suspended sediment yield of 68 t km
−2
year
−1
when considering the flow season to be approximately 4 months per year. Such values are considerably higher than those reported from continental Antarctica; however, they are lower compared to most of the Arctic catchments.
High Latitude Dust (HLD) deposition in the surface snow layer in two distant locations in Svalbard (Hornsund and Pyramiden) were collected during the June/July 2019 field campaign and examined in the ...laboratory. Despite the differences in their climate and topography, both locations are characterised by very similar spatial patterns of the deposition. On the one hand, strong linear negative relationship between the altitude of the sample taken and its concentration was found in low altitude (below 300 m a.s.l.), suggesting a strong influence of local HLD sources. On the other hand, almost constant concentrations were found at higher elevated sampling sites (above 300 m a.s.l.). This suggests a predominantly long-range transport in high altitude areas. The importance of local sources in the lower altitude corresponds well with the generally higher concentrations of HLD in the Pyramiden area. This region has a drier, continental climate and more deglaciated bare land surfaces, which favour more sediment to be uplifted in comparison with the more maritime climate of Hornsund area in the southern part of Svalbard. The spatial division between the local and long-range transport is supported by the proportion of certain lithophile elements in the altitude gradient.
Glaciers in central Svalbard are retreating since their Little Ice Age maximum, dated in the area to around 1900. Past areal extent of glaciers can confidently be reconstructed based on end moraine ...position. However, reconstructions of thickness and volume of glaciers remain relatively more complicated and uncertain. In this study, past changes in thickness and volume of the Ferdinand Glacier was reconstructed based on Structure-from-Motion techniques and field dGPS measurements in combination with analysis of historic photos from 1908 and aerial photos from 1938. According to the comparison of the historic and recent photograph, the 1908 glacier front height was estimated to 50 m and the glacier volume to 91.5 mil m
3
and the 1938 glacier volume estimated to 76.1 mil m
3
, in comparison to 6.29 mil m
3
in 2014. This means more than 90% loss of volume since 1938. Melting of the glacier in the first half of the twentieth century resulted in thinning and lowering of the glacier surface together with substantial ice volume loss, whereas the areal extent was almost not affected. Considering the 2014 mean ice thickness, together with ongoing climate warming, it is likely that the Ferdinand Glacier will completely disappear within the next 30 years.
A new non-invasive method based on picture analysis was used to estimate the conditions in Svalbard reindeer populations. The well-being of an individual subject is often expressed through visual ...indices. Two distinct reindeer populations were compared based on their antler parameters. Relative antler size and number of tines are variables supposed to reflect correspondingly the environmental conditions of sedentary populations within the growing season. The occurrence areas of two studied populations are distinctly isolated – separated with high mountain ridges, glaciers and fjords. The population in Petuniabukta occupies a sparsely vegetated region with harsh climatic conditions, whereas Skansbukta represents an area with continuous tundra vegetation cover, milder climatic conditions and, consequently, also a longer vegetation season. These environmental factors probably caused significant differences in the relative antler size and number of tines in the studied species. The Skansbukta population exhibited a larger relative antler size and higher number of tines than the population in Petuniabukta (both parameters differed significantly, p < 0.01). This difference reflects concisely the different environmental conditions of both locations. A comparison of Skansbukta population antler characteristics between years 2017 and 2018 did not reveal significant changes, most probably due to very similar atmospheric conditions in these two years (in terms of air temperature).
PDF
