Spitsbergen glaciers are in rapid recession. This is observed in both land-based glaciers [1
] and those terminating at sea [6
] and is regarded as a manifestation of the Arctic amplification effect, whereby changes in the net radiation balance tend to produce a larger increase in temperature near the pole than the planetary average [9
]. This process contributes to the expansion of low-albedo, ice-free sea surfaces with positive feedback (e.g., [11
In Spitsbergen (Svalbard Archipelago), surging glaciers represent a significant proportion of the glacier cover [6
]. They operate within the so-called “climate envelope” [23
], i.e., in optimal thermal and humidity conditions. Their behavior is mainly driven through snow mass supply in the glacier reservoir area (e.g., [24
]) and glacier enthalpy disorder, mainly at the ice-cliff area [22
]. The surging tidewater glaciers behave differently than the land-based glaciers. On land, the increased stress mainly propagates through the glacier surface from the accumulation area to the ablation zone where the maximum ice flow velocities are also measured. This sometimes manifests as an ice bulge [19
]. For tidewater glaciers, on the other hand, the properties of the active phase are often more obvious at the glacier ice-cliff. This phenomenon tends to be seen as an expanding crevassed zone [22
], as a result of the steep slope on the glacier surface propagating due to ablation of its lowermost part—the frontal zone. These features have been observed in Aavatsmarkbreen, for example. Other glaciers also show a characteristic lowering of the frontal zone due to ablation, and consequently intensive calving and retreat into deeper water from the pinning point. This is, for example, the case of Wahlenbergbreen, Mendeleevbreen, or Paierlbreenn [6
]. Meltwater and precipitation entering the glacier also enhances crevasse propagation towards the top of the glacier [22
]. The presence of crevasses in the frontal zone is important for determining tidewater glacier dynamics. In particular, crevasse formation increases the susceptibility of the glacier to mechanical ablation by calving [6
], facilitates the distribution of meltwater through en- and subglacial drainage systems [22
], particularly at low inclinations, crevasse allows penetration of direct radiation into deeper parts (also through multiple reflection of radiation from the crevasse ice walls [36
]) and facilitates ice-atmosphere and ice-ground/sea thermal conductivity. The length of the ice-cliff [20
] also influences thermal conductivity processes at the common ice–water–atmosphere boundary. As such, the ice-cliff wall also represents an additional heat and energy exchange zone. The glacier behavior is also influenced by the depth of the fjord into which the glacier flows [37
]. Thus, glaciers terminating in deeper parts of fjords are more susceptible to form a dense network of crevasses, further supplying heat to the underwater sections of the ice-cliff. This effect is particularly pronounced in areas where warmer West Spitsbergen Current waters penetrate deeply into the fjord [40
Regardless of the mechanisms determining the surging behaviour, a common sign of the active phase from all surging glaciers is the quick and constant change in geometry of the glacier frontal zone. If the ice-cliff bent towards the sea (convex), it is indicative of an advancing phase, whilst a bending towards the land (concave) is a sign of glacier retreat through intensive calving. This geometry is indeed representative of its dynamic state.
The purpose of this study is to analyze Spitsbergen tidewater glaciers using selected morphometric parameters of the frontal zone. This study combines data from 110 tidewater glaciers, including surging glaciers. Here, data from 1936 to 2017, both from recessive and advancing fronts is analyzed. In particular, the study focuses on annual geometrical changes of glaciers surging in the 1985–2017 period. Frontal morphometry was thus assessed as potential indicator to determine the initiation and termination of the active phase of the glacier surge. These data was used to forecast the initiation of active phases in 2017 and later, based on frontal morphology data from the 2014–2017 period. The results suggest that the “glacier buttresses system” of the frontal zone anchored on land plays a potential role on ice-cliff stabilization.
2. Materials and Methods
Landsat 7 Enhanced Thematic Mapper Plus (ETM+) satellite images with 30 m × 30 m resolution (543 bands) were collected from the summer seasons in year 2000 supplemented with a few in 2002. Landsat 8 Operational Land Imager/Thermal InfraRed Sensor (OLI/TIRS) imagery (654 bands) were collected for the 2014, 2017, 2018, and 2019 seasons (Table S1
: Emblems of topographic maps and IDs and acquisition dates of Landsat satellite images used in the research). These images were downloaded using the EarthExplorer browser [41
]. They were published by the United States Geological Survey (USGS) and the National Aeronautics and Space Administration (NASA) in the public domain. The selected data cover the ablation season. Topographic maps at 1:100,000 scale published by Norwegian Polar Institute (old and new editions [42
]) were used to define the ice-cliff edges for the years 1936, for the 1960s and 1970s, and partly for the 1990s. The maps from the older edition were georeferenced to the UTM 33 coordinate system using the ED50 ellipsoid (EPSG:23033) and then transformed into ETRS89 (EPSG:25833). Older Landsat 5 Thematic Mapper (TM) (543 bands) images from the period 1985–1998 and data described earlier were used to track yearly changes in the morphometry of 15 selected glaciers (1985–2017) (Table S2
. IDs and acquisition dates of Landsat satellite images for selected tidewater glaciers in Spitsbergen in the period 1985–2019). For a few cases Terra ASTER ©
NASA satellite scenes were used. Collected satellite images were also used to digitize the surface area of glaciers on available imagery in the year (max. 5 years) before the occurrence of the active phase of the glacier surge (see Table S2
—data pointed by red color of font). The vector layers (polygons) were used to calculate the basic morphometric parameters of a given glacier in order to examine the relationship between them and morphometry of the frontal zone. The average glacier slope is determined as the ratio between the elevation difference (maximum and minimum altitudes of the glacier found using the TopoSvalbard portal [43
]) and the length of the glacier measured along the central line. The compactness coefficient was calculated as the ratio of the glacier perimeter to the circle perimeter of area equal to the glacier area.
The data were analyzed using QGIS software (different versions). The ice-cliff line was delineated (vector layers) manually in a 1:20,000 scale. The composition of 543 (654) spectral bands clearly highlights the glacier ice area (blue), the non-glaciated area on land (brown, red) and sea water area (black, dark navy blue). For maps, the glacier front delineated in the original study was used as the cliff line.
The length of the ice-cliff line may vary between seasons, particularly depending on whether the image was taken at the beginning or the end of the ablation season. Uniform quality images from the whole of Spitsbergen are not available from the same day, due to variable cloud cover, different glacier exposure (shading), or other variables such as the presence of pack ice. The glacier range defined in the maps used were also based on aerial photographs and satellite images taken on different days for the same reasons.
This study assumes that the glacier frontal zone reacts clearest and fastest to changes in glacier dynamics than any other glacier sections. The following definition of the frontal zone (Figure 1
) was used here as standard: the “frontal zone Ag” of tidewater glaciers is defined as the section contained within the Ac
circle with a diameter Dc
equal to the distance between the parts of the glacier ice-cliff Lc
anchored on land.
Following the definition of the glacier frontal zone, the morphometric indicators—”glacier front dynamics indicator CfD
” and “ice-cliff balance indicator CfE
”—were defined. Thus, CfD
represents the ratio of glacier frontal zone area Ag
to circle area Ac
close to 1 or higher represents a convex frontal zone typical of advancing glaciers (Figure 2
a). The highest absolute value of CfD
= 1.11 was found for Negribreen in 1969. A value of CfD
above 1 (extreme cases) usually means that the frontal zone has spilled out and moved far out into the sea, beyond the outlet of the valley that limits it, and in consequence beyond the perimeter of the theoretical circle Ac
. A CfD
of approximately 0.5 represents a semi-circular frontal zone with a cliff line closely following the diameter of the circle and usually presenting very little variability (Figure 2
b). Finally, a CfD
close to or below 0 is indicative of a clearly concave glacier front in deep recession, where the inflexion point(s) of the ice-cliff line is often at a long distance from the line between the anchor points (Figure 2
c). A negative value appears when the greater part of the frontal zone is outside the circle area Ac
. Then this “minus” area needs to be subtracted from the value of the frontal zone area lying inside the circle (usually lateral part anchored on land). The lowest CfD
= −1.15 was found for Samarinbreen in 1961.
The ice-cliff balance indicator, CfE
, is the ratio of the circle diameter length Dc
to the ice-cliff length Lc
The absolute value (a.v., modulus), used to compared among different glaciers, represents the degree of curving of the ice-cliff. Thus, an absolute of 1 indicates a straight line; that is, that the length of the ice-cliff Lc
is equal to the circle diameter Dc
. This can be achieved by any glacier during the evolution between the concave and convex shape of its frontal zone (and vice versa). Ice-cliff bending level increases as the absolute values approach 0, with the number of inflexion points increasing concomitantly. The greatest curvature of the ice-cliff was found for Sefströmbreen in 1990 (|CfE
| = 0.21). The symbols + and − are used to distinguish between convex (+) and concave (−) glaciers. A negative sign is when most of the measured ice-cliff length Lc
is located between the circle diameter Dc
and the part of the frontal zone closer to the glacier body. In turn, when most of the cliff line exceeds the circle diameter Dc
towards the sea, the sign for CfE
is positive (cf. Figure 2
3.1. Geometric Parameters of the Glacier Ice-Cliffs in Spitsbergen (1936–2017)
Ice geometry data from Spitsbergen glaciers (Table 1
) were compiled for the year 1936 (28 glaciers; no data available from the NW and N parts of Spitsbergen), the period 1961–1966 (35 glaciers; no data available from the N and NE parts of Spitsbergen), 1969–1977 (17 glaciers; no data available from S Spitsbergen), 1990 (73 glaciers), 2000, 2014, and 2017 (110 glaciers each year). The different periods include different combinations of glacier systems (their complexity). For example, Strongbreen was configured as one glacier system in 1936 while it is currently shaped as several separate land-terminated (e.g., Karlbreen) and tidewater glaciers (e.g., the Kvalbreen–Indrebøbreen system, Moršnevbreen, the Sokkelbreen–Naglebren–Nuddbreen system ⇒ Strongbreen, the Vindeggbreen–Persejbreen system), as a result of recession.
Due to the asymmetrical distribution of morphometric parameters of the glaciers in terms of their area and their frontal zones, the calculation of average values for the glaciers population from each period took into account the median and interquartile range (IQR) values. Glaciers between 19.5 km2
and 110.4 km2
analyzed here (within the IQR; based on data by Błaszczyk et al. [20
]) can be considered as typical in terms of surface area.
For the following parameters—Lc, Dc, Ag, and Ac—the results show that the highest median appeared in 1936. The values subsequently decreased until the year 2000. Thus, the median ice-cliff length (Lc) decrease by 1.6-fold, the median valley width at the glacier front anchoring points (Dc) showed a 2-fold decrease, the frontal zone area (Ag) decreased by 4.9-fold, and the median value of area of the circle surrounding the glacier frontal zone (Ac) decreased by 3.8-fold. However, the period 1969–1977, when the values were slightly higher, was an exception. In addition, an increase in Lc was observed between 2000 and 2014 followed by a 1.1-fold decrease. Ag, on the other hand, showed a 1.3-fold decrease first followed by a 1.2-fold increase measured in 2017. The CfD and CfE indicators also show a general downward trend, suggesting that ice-cliffs are presenting an increasingly recessive nature. The exception was the year 2000, when these indicators increased.
If the interaction between CfD
for each glacier is considered, then most of the glaciers were in a state of recession throughout all the periods discussed here (negative CfE
values and CfD
values below 0.5) (Figure 3
). However, there is always a group of advancing glaciers (or shortly after the active phase of the glacier surge), representing 10.5% (1990) to 18.2% (2000) of the population of tidewater glaciers. These glaciers are characterized by a positive CfE
value and a CfD
value often above 0.5.
3.2. Frontal Zone Morphometry of the Retreating Glaciers
The values of morphometric indicators of the glacier frontal zones during recession phase were plotted against the mean annual air temperature (MAAT) measured at the Svalbard Airport for each of the different periods considered (Figure 4
). Glaciers showed a less intense recession following the minimum temperatures recorded at the beginning of the 20th century, presenting the highest median CfD
= 0.39 and CfE
= 0.81 a.v. in 1936). In contrast, the same glaciers showed their strongest recession episode over 30–40 years later, where the median values for both indicators dropped to CfD
= 0.24 and CfE
= 0.63 a.v., (median from 1969–1977). Until the end of the 20th century, the median values increased reaching CfD
= 0.36 and CfE
= 0.78 a.v. in 2000. The recession process further intensified over the first 17 years of the 21st century, accompanied by a decrease in CfD
, down to 0.26 and 0.69 a.v., respectively, in 2017. Both values were close to the levels observed in the 1990s, which was followed by the largest number of surging tidewater glaciers in Spitsbergen.
In relation to ice-cliff exposure in 1990, south-east and north-west facing glaciers showed the strongest recessive nature (Figure 5
). These glaciers showed a median CfD
of 0.11 and a relatively low CfE
(a.v.) compared to the other glacier groups.
In the year 2000, a clear growing trend was observed for the dynamically active of most glacier fronts, apart from those from the southern sector. This was most noticeable for ice-cliffs facing the south-east sector, with CfD values reaching over 0.44. The ice-cliff lengths in relation to the circle diameter also shortened, presenting median CfE (a.v.) of approximately 0.80.
More recessive stage was also observed for the 2014–2017 period, apparent as a clearly visible melting of the most dynamic part of the glacier frontal zones, particularly obvious for ice-cliffs facing to the southern sector. At this stage, ice-cliffs withdraw considerably with the CfD reaching its lowest recorded value at −0.06. This curving is also reflected in the lowest median CfE reaching 0.46 (a.v.). A significant decrease in CfD and CfE was also observed from north-facing glaciers, and to a lesser extent, for west- and north west-facing fronts. The fluctuation in CfD and CfE was smaller for east- and south west-facing glaciers.
3.3. Frontal Zone Morphometry of the Advancing Glaciers
Over the years 1990–2017, advancing ice-cliffs were found in glaciers from all geographical aspects, and roughly around the same number of cases (up to 5% difference). This pattern was particularly obvious for all north-, east-, or south west-facing tidewater glaciers from Spitsbergen, with fewer cases found from north-east (8% difference), south, and west. However, the proportion of cases changed over this period. Thus, in 1990–2000 the most active glacier fronts were found particularly in the N–S axis (e.g., Petermannbreen, Monacobreen, Waggonwaybreen, Paierlbreen, and Storbreen) and with north-east exposure (e.g., Davisbreen, and Inglefieldbreen-Nordsysselbreen). In turn, in 2014–2017, active ice-cliffs dominate in the E–W axis (e.g., Vindeggbreen-Persejbreen, Sjettebreen, Arnesenbreen, and Strongbreen) and from south west-facing glaciers (e.g., Blomstrandbreen, Kollerbreen, and Marstrandbreen).
Annual variations in the frontal zone geometrical indicators were analyzed for 15 glaciers. These glaciers experienced an active phase of the glacier surge at some point during 1985–2017 (based on: Murray et al. [45
]; Błaszczyk et al. [20
]; Sund et al. [19
]), or/and the advance could be directly observed from data analyzed in this study (Figure 6
, Table 2
). As the glaciers advance, their CfD
values changed from 0.33 (0.18 to 0.40 of IQR) during the quiescent phase to 0.61 (0.54 to 0.71 of IQR) during the active phase. The median CfE
changed from −0.72 (−0.81 to −0.56 of IQR) during the quiescent phase to 0.78 (0.69 to 0.88 of IQR) during the active phase of the glacier surge.
The comparison presented in Table 2
allows assessing how the timing of the initiation and end of the active phase can be determined based on CfD
. This relation differed slightly for the published data: by ±0 to 4 years for the beginning and ±1 to 6 years for the end of the active phase. The average duration of the active phase based on data published for 10 glaciers was approximately 3–10 years, while the CfD
indicators showed an average active phase of 6–10 years. Some of the published results, however, appeared in print during the active phase and the glacier could have continued surging afterwards.
The increase in CfD
was nearly concomitant to the glacier movement for larger glaciers (e.g., Nathorstbreen, Monacobreen, and Paierlbreen). However, a delay of few years was also observed (e.g., Mendeleevbreen and Wahlenbergbreen). A correlation analysis between the values of both indicators also show a delay of up to five years before the indicator values jump (Table 3
). The largest significant correlation of indicators at the significance level of 0.05 took place one year and five years before the active phase. In all cases, the active phase ended with an obvious decrease in CfD
; thus, entering a quiescent phase characterized by small interannual changes in these values.
Preliminary analysis indicates that the length of the ice-cliff just before the active phase of the glacier surge is well correlated with the glacier surface slope and the glacier compactness. The gentler the slope of the glacier surface and more complex the glacier in terms of its geometry, the longer its ice-cliff. This is because the glaciers that are most complex in shape are usually large valley glacier systems with numerous tributaries. These studies will be continued.
3.4. Application of CfD and CfE Indicators in the Classification of Spitsbergen Tidewater Glaciers in Terms of Dynamics
Interannual changes in indicator values were presented to describe the dynamic state of five Spitsbergen tidewater glaciers with the most complete data sets for the period 1985–2017: Monacobreen (to 2019; N part of Spitsbergen), the Vindeggbreen–Persejbreen system (E part of the island), the Osbornebreen–Vintervegen system and Blomstrandbreen (both in W part of Spitsbergen), and Paierlbreen (S part of the island) (Figure 7
; see Table S2
). The data indicates that most of the time the ice-cliffs are characterized by slight interannual changes in indicator values. The situation changes significantly with the beginning of the active phase of the glacier surge when the increase in values appears as a clear deviation in the I quadrant of the graph (advance), and this is also recorded in Figure 6
. A similar clear deviation occurs in the III quadrant during the transition of the active phase to the quiescent phase. Then in Figure 6
values go negative (retreat).
The analysis of the interannual variation in the CfD and CfE indicators allows describing the following dynamic models for tidewater surging glaciers in Spitsbergen:
At the beginning of “the active phase of the glacier surge” both CfD
indicators increase rapidly by 3–5 times during approximately 1–5 years. For larger glaciers, the rate of increase can reach a maximum of a 10× increase (I quadrant in Figure 7
and Figure 8
). In this phase, the frontal zone protrudes (convex shape) and the glacier moves forward. Then the ice-cliff position is marked by slight fluctuations or “stagnates”, and numerous inflexion points associated with intensive calving appear in the cliff line.
After the active phase, the glacier first loses its frontal zone convexity, mainly as a result of intensive calving, and it is subject to “recession” (including the quiescent phase of the glacier surge). At this point, CfD and CfE values decrease interannually to an average of 0.05–0.06 (for CfE the sign changes to negative; III quadrant).
Subsequently, the glacier can enter a “deep recession phase”, when its frontal zone is strongly concave, especially for the largest glaciers (IV quadrant). “Glacier buttresses” are also observed, i.e., parts of the glacier front anchored on land, from which the ice-cliff bends into an arch. During the quiescent phase, CfD and CfE values change very little interannually and are ca. 0.015–0.025. The value of CfD decreases the most (it can even be negative), with the CfE value slowly increasing from −1 to approximately −0.5.
The glacier begins to lose its maximum ice-cliff concavity at the end of the recession with “the frontal zone filling and the slow forward movement” beginning (II quadrant). At this point, the CfD value slowly increases and CfE value slowly decreases (from −0.5 to −1) until the protrusion of the glacier front and the value changes to plus sign.
The presented model was adopted for Monacobreen for the 1985–2019 period (Table 4
). Based on the indicators, the beginning of the active phase (I) of the glacier surge was determined in 1991–1992. For the first 2 years, the frontal zone was getting convex and the glacier advanced about 1100 m in western part to about 1500 m in eastern part of the cliff line compared to 1991. Then it entered a period of stagnation/minor fluctuations in the position of its ice-cliff, rising slightly in the western part and about 700 m in the eastern part of the cliff. At the end of the active phase (2000–2001), retreat began with the still convex frontal zone. The active phase lasted until 2001–2002 (10 years). After this period, the glacier entered the quiescent phase of the glacier surge (negative CfE
). Slow withdrawal of the ice-cliff position was accompanied by ablation by calving and melting (concave shape). By 2007, the glacier withdrew from about 700 m in the eastern part of the ice-cliff to about 800–900 m in the western part. The appearance of inflexion points (2005) indicates probably an important role of the outflow of subglacial waters. After 2008, the quiescent phase was marked by some recovery in glacier behaviour, reflected in changes in the indicators values from year to year up to 2018. The glacier retreated by 500–600 m. The quiescent phase lasted 17 years. In 2018–2019, a new active phase (II) of the glacier surge began (positive CfE
), as before, from the bending of the ice-cliff line towards the sea and an advance of about 800–900 m on the central line of the glacier.
Interannual variations in CfD
estimated on the basis of the data from 2014 and 2017 were also analyzed including all glaciers (Figure 8
) to determine which of them may experience an active phase of glacier surge in 2017 and later according to the model proposed. In addition, a class represented stagnant glaciers has been specified based on the IQR of interannual variations of CfD
. In this class CfD
varied from −0.02 to 0.01 per year and CfE
from −0.01 to 0.02 per year during the analyzed period.
A total of 28% of the 110 tidewater glaciers were in deep recession. In the 2014–2017 period, one-third were stagnant glaciers with an uncertain future behavior, although this might be a sign of an impending active phase of the glacier surge. For example, Nathorsbreen, Tunabreen, and Persejbreen showed interannual differences for CfD and CfE close to 0 about 4 years before the active phase of the glacier surge. Eleven percent of glaciers should have already been experiencing an active phase of the surge.
This classification was further compared with other information from these glaciers, particularly whether a clear advance was observed on Landsat satellite scenes in 2017 (6 glaciers), in 2018 (additional 7 glaciers), and in 2019 (additional 11 glaciers) (Figure 9
). The advance was identified as a forward shift of the ice-cliff in relation to previous years, and based on the presence of a crevassed zone within the glacier frontal zone Ag
, both characteristic of rapid glacier movement during the surge [7
]. Eleven of the glaciers showed overlapping classifications as those clearly advancing and showing movement forward (Aavatsmarkbreen, Midtbreen, Vaigattbreen, Wahlenbergbreen, Arnesenbreen, Strongbreen → Moršneevbreen, Svalisbreen, Emmabreen, Tunabreen, Allfarvegen, and Moltkebreen), 7 as stagnant (Marstrandbreen, Nordenskiöldbreen, Kvalbreen, Sonklarbreen, Crollbreen, Markhambreen, and Recherchebreen), 5 as deeply withdrawn, ready for advance (Negribreen, Thomsonbreen, ve Osbornebreen, Fjortende Julibreen, and Lilliehöökbreen → Bjørlykkebreen), and 1—Monacobreen—as retreating. Five glaciers, classified as advancing, were still (2019) in recession/quiescent phase (Fjerdebreen, Chauveaubreen, the Heuglinbreen–Hayesbreen–Königsbergbreen system, and Nansenbreen) or stagnant (Kollerbreen). In the case of Johansenbreen, classified in Figure 8
and Figure 9
as a stagnant glacier, an ice bulge is observed on satellite imagery (Landsat 8—2019) moving down glacier, while the medial moraine has been bent, both of which are typical first characteristics of glacier surge [19
The morphometric indicators used here, the frontal zone dynamics indicator CfD and the ice-cliff balance indicator CfE, allow determining of the dynamic state of tidewater glaciers and classifying them as: deeply receding glaciers, glaciers fulfilling the frontal zone/showing a forward movement, glaciers clearly advancing (active phase of the glacier surge), those showing signs of recession (quiescent phase), and stagnant glaciers. In addition, they allow forecasting future glacier behavior using remote sensing methods (e.g., satellite imagery, aerial photographs, laser scanning data, etc.).
The value of these indicators just before the surge is related to the size of the glacier and the complexity of the glacier system, the length of the ice-cliff and the average slope of its surface. The beginning and end of the active phase of the glacier surge can be identified as a sudden change in the ice-cliff morphometric indicators, as exceeding by several times the median of their interannual fluctuations in the order of approximately 0.05–0.06. This, in turn, gives the opportunity to estimate the duration of the active phase, which in the case of the 10 most-studied Spitsbergen tidewater glaciers appears to last on average 6–10 years.
The analysis shows a clear difference in morphometry and the behavior of the surging glaciers between smaller and large tidewater glaciers. One of the elements affecting the rate of the dynamic processes and their scale is the presence of glacier buttresses, which drives the distribution of the internal stresses in glaciers to the land anchored part, ensuring the stabilization of the ice-cliff. Buttresses are especially characteristic of large glaciers which can reach larger linear recession values, but also react more violently to the jump of the ice-cliff stability node. This also triggers the propagation of crevasses from the ice-cliff line up the glacier, especially in cases of anchoring the ice-cliff closer to the valley mouth. The presence of the glacier buttress system is probably another variable regulating the distribution of forces inside the glacier, which should be included in the modelling of the calving processes of tidewater glaciers.
The morphometric model proposed here is of limited use for glaciers with very little contact with the sea and in the case of ice-cliff shading. Glaciers pinning on islands/capes are also a problem. In this case, each part of the ice-cliff between the island(s) and the land should be treated as a separate section. Glaciers that have not lost their complexity are best suited for long-term analyzes.
Currently, Spitsbergen tidewater glaciers show a strong recession pattern, as expected following Arctic amplification models. Thus, the morphometric indicators presented here also suggest a likely intensification of the phenomenon of the glacier surge in the coming years.