In order to study the seasonal and inter-seasonal variations in radio-wave velocity (RWV), radiophysical investigations were made at Hansbreen, a polythermal glacier in Spitsbergen, in July– August 2003 and April 2004. These investigations included repeated radar profiling (20 and 25 MHz) along a transverse profile, repeated common-midpoint measurements, continuous radar measurements during 8 days at a fixed site, meteorological observations, and continuous ice surface velocity monitoring by differential GPS. Seasonal and inter-seasonal RWV changes in the temperate ice layer are attributed, respectively, to rapid water redistribution within it during the summer, and to variations in water content from 2.1% in summer to 0.4% in spring. The reflection properties of the temperate ice layer correlate well with the air temperature, with a nearly semi-diurnal time lag. The temporal variability of the reflection properties of the internal horizon suggests enlargement of water inclusions or water drainage from the horizon. Repeated profiling shows a stable spatial pattern in bed reflection power interpreted as changes in water content controlled by bedrock topography. The spatial variations of internal reflection energy along the repeated profile correlate with the thickness of the cold ice layer and the occurrence of drainage and crevasse systems.

Evidence for ice streams in the Laurentide ice sheet is widespread. In the region of northern Keewatin and the Boothia Peninsula, Nunavut, Canada, palaeo-ice streams have been recognized, but their location, size and potential role in ice-sheet dynamics are poorly constrained. Based on the interpretation of satellite imagery, we produce a palaeo-ice-stream map of this region. Glacial directional landforms, eskers and moraines were mapped and integrated into landform assemblages using a glacial geological inversion model. Palaeo-frozen bed areas were also identified. Relative age of the geomorphic swarms was assessed by cross-cutting relationships and radiocarbon ages where available. Using this information we obtained a glaciologically plausible picture of ice-stream evolution within the northernmost Laurentide ice sheet. On the M’Clintock Channel corridor, three generations of pure ice streams are found. On Baffin Island and the Gulf of Boothia, glaciation was dominated by frozen-bed zones located on high plateaus and ice streams running along the troughs, i.e. topographic ice streams. A massive convergent pattern at the head of Committee Bay drained ice from both the Keewatin and Foxe sectors and was probably one of the main deglaciation channels of the Laurentide ice sheet. Finally, our results indicate that streaming flow was present in the deep interior of the Laurentide ice sheet, as recently shown for the Greenland and Antarctic ice sheets.

Thrust-block naled in front of Kuannersuit Glacier, West Greenland, appears to have formed during the termination of a terrestrial surge event by a combination of enhanced winter runoff, rapid advance of the glacier terminus, and proglacial stress release by thrusting and stacking of naled blocks. This process is equivalent to the formation of thrust-block moraines. The thrust-block naled consists of at least seven thrust sheets, which are characterized by stratified ice with beds composed of a lower debris-rich lamina, an intermediate dispersed lamina and a top clean-ice lamina, and underlain by frozen outwash deposits. The thrust-block naled differs from basal stratified ice in the absence of internal deformation structures, a relatively low debris concentration, a clay-rich particle-size distribution and a preferential sorting of lighter minerals. The oxygen isotope composition of the thrust-block naled is indistinguishable from δ18O values from meteoric glacier ice and bulk meltwater, but different from basal stratified ice facies. The d–δD relationship indicates that thrust-block naled has been formed by freezing of successive thin layers of bulk waters with variable isotopic composition, whereas basal stratified ice has developed in a subglacial environment with regelation. This work shows that the association between proglacial naled and rapidly advancing glaciers may have significant consequences for the proglacial geomorphology and the interpretation of basal ice layers.

Bakaninbreen is a polythermal glacier in southern Spitsbergen, Svalbard, which surged between 1985 and 1995. For 9 days in spring 1987, when the surge front was travelling at ∼2.5-3.0 m d–1, three single-component geophones and two accelerometers were deployed in a T-shaped array immediately downstream of the surge front to record seismic emissions. The events were characterized by their waveforms and spectral content. At least three different categories have been identified: impulsive P- and S-waveforms, surface P- and S-wave trains, and harmonic (75-130 Hz) events. We interpret the impulsive events to originate at the base of the glacier, at or downstream of the surge front; the surface P- and S-wave trains from near-surface brittle fracture associated with the surface expression of the surge front itself; and the harmonic events from deep sources that involve resonance in a water-filled fracture, associated with the base of the surge front. We believe the basal events are related to the activation of stagnant ice downstream of the surge front, which allows water to access the bed and provides the mechanism for its propagation.

Aldegondabreen is a small valley glacier, ending on land, located in the Grønfjorden area of Spitsbergen, Svalbard. Airborne radio-echo sounding in 1974/75, using a 440 MHz radar, revealed a polythermal two-layered structure, which has been confirmed by detailed ground-based radio-echo sounding done in 1999 using a 15 MHz monopulse radar. The 1999 radar data reveal an upper cold layer extending down to 90m depth in the southern part of the glacier, where the thickest ice (216 m) was also found. A repeated pattern of diffractions from the southern part of the glacier, at depths of 50–80 m and dipping down-glacier, has been interpreted as an englacial channel which originates in the temperate ice. From joint analysis of the 1936 topographic map, a digital elevation model constructed from 1990 aerial photographs and the subglacial topography determined from radar data, a severe loss of mass during the period 1936–90 has been estimated: a glacier tongue retreat of 930 m, a decrease in area from 8.9 to 7.6 km2, in average ice thickness from 101 to 73 m and in ice volume from 0.950 to 0.558 km3, which are equivalent to an average annual balance of –0.7 mw.e. This is comparable with the only available data of net mass balance for Aldegondabreen (–1.1 and –1.35m w.e. for the balance years 1976/77 and 2002/03) and consistent with the 0.27˚C increase in mean summer air temperature in this zone during 1936–90, as well as the warming in Spitsbergen following the end of the Little Ice Age (LIA), and the general glacier recession trend observed in this region.

Our ultimate objective is to study the mass-balance variations of Polar Ural glaciers during the last millennium. We use mass-balance data for two glaciers between 1957 and 1981, climate data obtained by instrumental observations during the 20th century, and tree-ring data compiled for the last 1000 years. Because there is a high correlation between measured glacier mass-balance and climate variables, we reconstruct glacier mass balance for the 20th century using regression equations. Similarly, we use regression equations relating measured climatic variables to tree-ring widths to reconstruct glacier mass balance for the last millennium. According to our reconstructions, the most extensive period of negative mass balance occurred in the late 10th/early 11th century AD, which corresponds to the Medieval Warm Period. A prolonged period of positive glacier mass balance began after the mid-11th century, a time commonly accepted as the onset of the Little Ice Age. This cooling period has three maxima, the last from the early 17th to mid-19th century. Until the beginning of the 20th century, cumulative mass balance over the last millennium varied between ±8mw.e. However, glacier mass balance in the second half of the 20th century is lower than it has been for the past millennium, and cumulative mass balance is now -10mw.e. Polar Ural glaciers are important indicators of regional climate change and should be incorporated into a worldwide glacier-monitoring programme.

Glacier fluctuations from key Vatnajökull outlets have been redated using tephrochronology coupled with two lichenometric techniques to ascertain the timing of the Little Ice Age (LIA) maximum in southeast Iceland. An updated tephrochronology for southeast Iceland (both the number of tephra layers present and their geochemical signatures) indicates a LIA maximum for both glaciers between AD 1755 and 1873. Based on a population gradient approach, lichenometrically dated moraines along the margins of Skálafellsjökull and Heinabergsjökull narrow this window to the early to mid-19th century respectively. These revised chronologies, in addition to emerging evidence from elsewhere in Iceland, support a late 18th- to early 19th-century LIA glacier maximum. In contrast, the Norwegian LIA glacial maximum is strongly centred around AD1750. This implies differing glaciological responses to secular shifts in the North Atlantic Oscillation. Such revisions to the Vatnajökull record are crucial, as accurately identifying the timing and delimiting the spatial extent of the Icelandic LIA glacier maximum will allow further light to be shed on glacier–climate interactions in the North Atlantic.

Historical records, photographs, maps and measurements were used to determine changes in the length, geometry and volume of Rabots Glaciär, Sweden, in response to a ∼1°C warming that occurred early in the 20th century. The glacier’s initial rate of retreat from its 1910 maximum was ~2.0 m a–1. After a sharp increase to ∼11.7 m a–1 between 1933 and 1946, the mean retreat rate decreased to ∼5.5 m a-1 between 1946 and 1959. Thereafter the rate of retreat increased to ∼11.0 m a-1 and has remained relatively constant to the present time. Concomitant decreases in ice volume were estimated to be 77.3 × 106m3 between 1910 and 1959, 51.1 × 106m3 between 1959 and 1980, at least 10.4 × 106m3 between 1980 and 1989, and 14.4 × 106m3 between 1989 and 2003. The total volume change over the last 93 years is estimated at ∼153.2 × 106m3 corresponding to 1.6 × 106m3a–1.. The magnitude of the ongoing changes in length and volume suggests that Rabots Glaciär has not yet completed its response to the earlier climatic warming. In contrast, several nearby glaciers, most notably Storglaciären, have completed their adjustments and established new steady-state profiles as a result of having shorter response times.

Three receding glaciers on Spitsbergen were examined on the basis of a 1936 topographic map and field investigations during the summers of 1995 and 2001. Håbergbreen, the largest glacier, has undergone the most intensive recession due to its relatively low altitude. There are two important manifestations of glacial recession: (1) the retreating glaciers leave rocky outcrops in the upper or steeper mountain slopes, and (2) the edges of moving glacier tongues are being transformed into motionless ice-cored moraines in valleys. The glaciers under study have not been transformed into rock glaciers. The recession rate has been increasing since 1995, which can be interpreted as a result both of positive feedback initiated by 20th-century climate warming and of slight warming in the 1990s. The glaciers have not thawed enough in relation to the warming and rise of the equilibrium-line altitude (by at least 250–300 m since the beginning of the 20th century). Håbergbreen, already split up into four ice patches, will disappear without a sustained temperature decrease during the next few decades. Grumantbreen and Dryadbreen will survive as small mountain glaciers if winter snow precipitation does not increase.

Key issues of glacier monitoring are changes in glacier geometry and glacier mass. As accurate direct measurements are costly and time-consuming, the use of various remote-sensing data for glacier monitoring is explored. One technology used and described here is airborne laser scanning. The method enables the derivation of high-quality digital elevation models (DEMs) with a vertical and horizontal accuracy in the sub-metre range. Between September 2001 and August 2002, three laser scanner data acquisition flights were carried out, covering the whole area of Engabreen, Norway, and corresponding well to the measurement dates for the mass-balance year 2001/02. The data quality of the DEMs is assessed (e.g. by comparing the values with a control area which has been surveyed independently or GPS ground profiles measured during the flights). For the whole glacier, surface elevation change and consequently volume change is calculated, quantified and compared with traditional mass-balance data for the same time interval. For the winter term, emergence/submergence velocity is determined from laser scanner data and snow-depth data and is compared with velocity measurements at stakes. The investigations reveal the high potential of airborne laser scanning for measuring the extent and the topography of glaciers as well as changes in geometry (Δarea, Δvolume).

Precise airborne laser surveys were conducted during spring in 1996 and 2002 on 17 ice caps and glaciers in the Svalbard archipelago covering the islands of Spitsbergen and Nordaustlandet. We present the derived elevation changes. Lower-elevation glaciers in south Spitsbergen show the largest thinning rates of ∼ 0.5 m a-1, while some of the higher, more northerly ice caps appear to be close to balance. The pattern of elevation change is complex, however, due to several factors including glacier aspect, microclimatological influences and the high natural annual variability in local accumulation and ablation rates. Anomalous changes were observed on Fridtjovbreen, which started surging in 1996, at the start of the measurement period. On this glacier, thinning (of > 0.6 m a-1) was observed in the accumulation area, coincident with thickening at lower elevations. Asymmetric thinning was found on two ice caps on Nordaustlandet, with the largest values on the eastern side of Vestfonna but the western slopes of Vegafonna. The mean elevation change for all ice masses was -0.19 m a-1 w.e., which is 1.6 times the net mass-balance value determined for the last 30 years. Using mass-balance sensitivity estimates for Svalbard suggests that the implied increase in negative balance is linked to warmer air temperatures in the late 1990s. Multiple linear regression suggests that mass balance is most closely correlated with latitude, rather than mean altitude or longitude.

There are relatively few comparisons between synthetic aperture radar (SAR) observations and glacier mass-balance measurements. More typically, SAR has been deployed to identify changes in the end-of-summer snowline and other facies boundaries. In this paper, we analyze the geophysical processes affecting SAR amplitude data over two Arctic glacier systems in northern Scandinavia to assess the potential of SAR observations for the retrieval of surface balance parameters. Using a backscatter model and in situ data, we identify the controls on SAR imagery in terms of mass-balance measurement and discuss the glaciological parameters which can reasonably be derived from multi-temporal SAR data. Our results show that amplitude SAR imagery, in the absence of in situ measurements, is not capable of providing meaningful mass-balance data. We show that backscatter from temperate glaciers is affected primarily by snow grain-size and density, and therefore processes such as firnification or depth-hoar formation can complicate the analysis of imagery. We conclude that SAR imagery over temperate glaciers can provide valuable proxy information but not direct mass-balance terms.

Future climate warming is predicted to be more pronounced in the Arctic where approximately two-thirds of all small glaciers on Earth are located. A simple mass-balance model was applied to 42 glaciers and ice caps north of 60° N to estimate mass-balance sensitivities to a hypothetical climate perturbation. The model is based on daily temperature and precipitation data from climate stations in the vicinity of each glacier and ice cap. A regression analysis was made using a degree-day approach where the annual sum of positive daily air temperatures was correlated to measured summer mass balance, and the total annual snow precipitation was correlated to measured winter mass balance. The net mass-balance sensitivity to a hypothetical temperature increase of +1 K ranged from -0.2 to -2.0 m a-1, and an assumed increase in precipitation of +10% changed the mass balance by <+0.1 to +0.4 m a-1, thus on average offsetting the effect of a temperature increase by approximately 20%. Maritime glaciers showed considerably higher mass-balance sensitivities than continental glaciers, in agreement with similar previous studies. The highest sensitivities were found in Iceland, exceeding those reported in previous studies. Extrapolating our results, glaciers and ice caps north of 60° N are estimated to contribute ∼0.6 mm a–1 K–1 to global sea-level rise. Our results highlight the value of long-term mass-balance records and meteorological records in remote areas.

A survey of available mass-balance data shows that glaciers on arctic islands, i.e. mountain glaciers and ice caps in northern Canada, Greenland, Svalbard and the Eurasian islands, share mass-balance characteristics of low annual amplitude and small interannual variability. By contrast, glaciers around the Arctic (e.g. in Alaska, Iceland, mainland Scandinavia and northern Eurasia) can have exceptionally large annual amplitude and interannual variability but otherwise share characteristics with glaciers in lower latitudes. The arctic island glaciers occur in areas with low annual precipitation and high annual temperature variability, i.e. in dry-cold or continental regions. Most glaciers surrounding the Arctic (Alaska, Iceland and Scandinavia) occur in areas with high annual precipitation and low annual temperature variability, i.e. in wet-warm or maritime regions. Earlier mass-balance modelling showed that arctic island glaciers have low sensitivity to temperature changes consistent with their low mass-balance amplitude. However, very large changes in mass balance could occur on arctic island glaciers if the sea ice surrounding the arctic islands were reduced so that the climate of the arctic islands becomes more maritime.

In this paper, we report on an approach to estimate the contribution of Arctic glaciers to sea-level change. In our calculation we assume that a static approach is feasible. We only calculate changes in the surface balance from modelled sensitivities. These sensitivities, summarized in the seasonal sensitivity characteristic, can be used to calculate the change in the surface mass budget for given anomalies of monthly temperature and precipitation. We have based our calculations on a subdivision of all Arctic ice into 13 regions: four sectors of the Greenland ice sheet; the Canadian Arctic >74˚N; the Canadian Arctic <74˚N; Alaska, USA; Iceland; Svalbard; Zemlya Frantsa Iosifa, Russia; Novaya Zemlya, Russia; Severnaya Zemlya, Russia; and Norway/Sweden >60˚N. As forcing for the calculations, we have used the output from five climate models, for the period 2000–2100. These models were forced by the same greenhouse-gas scenario (IPCC-B2). The calculated contributions to sea-level rise in the year 2100 vary from almost zero to about 6 cm. The differences among the models stem first of all from differences in the precipitation. The largest contribution to sea-level change comes from the Greenland ice sheet. The glaciers in Alaska also make a large contribution, not because of the area they cover, but because they are more sensitive than other glaciers in the Arctic. The climate models do not agree on regional patterns. The runoff from Svalbard glaciers, for instance, increases for two models and decreases for the three other models. We conclude that the uncertainty due to a simple representation of the glaciological processes is probably smaller than the uncertainty induced by the differences in the climate-change scenarios produced by the models.

On western Spitsbergen, Svalbard, the amount of winter precipitation is insufficient to maintain the present-day mass balance of the local glaciers. Additional snow mass must be added to the precipitation to reach the observed accumulation rates of the glaciers. It was assumed in previous work that this additional mass is transported onto the glaciers by drifting snow and snow avalanches. This study is a first attempt to quantify the amount of snow mass added to the glacier mass balance by wind-transported snow. The wind field over an area of 60 × 50 km2 on western Spitsbergen was simulated for 24 idealized weather types by a mesoscale meteorological model on a 750 m grid. The resulting wind velocities and directions were coupled to a two-level snowdrift model. The model output clearly shows erosion and accumulation areas in the terrain. Comparison with the present glacier locations suggests that the glacier accumulation areas coincide with low wind speeds. Moreover, exposed areas with high wind speeds are mostly glacier-free in reality. Thus, the wind field and corresponding snowdrift gives an indication of the location of the present glaciers on western Spitsbergen.

Glacier mass balance and hydrology are strongly influenced by the distribution of snow accumulation at the start of the melt season. Two successive end-of-winter snow-cover surveys at Finsterwalderbreen, Svalbard, are here used to investigate the interannual variability in the spatial distribution of accumulation, and its relationship with topography. 40–62% of the variance in snow depth was not determined by elevation (assessed by linear regression of snow depth on surface elevation), which could not therefore necessarily be used as a sole predictor of the spatial distribution of accumulation here. Principal components (PC) analysis of the topographic variables elevation, slope, north–south and east–west aspects shows that only two of six PCs, determined for 2years’ sampling locations, had maximum loadings on altitude; aspect was more important, with maximum loadings on four PCs. Hierarchical cluster analysis was then applied to these PCs: significant correlations with accumulation in each of two terrain clusters were given by (1) elevation and slope, (2) east–west aspect only (1999); (1) elevation only, (2) no significant correlations (2000). There is strong interannual variability not only in the magnitude of winter accumulation (0.41 mw.e. in 1999, 0.58 mw.e. in 2000), but also in its spatial distribution, and its relationship with topography.

Tabular (massive) ground ice in periglacial areas of the Russian Arctic (Barents and Kara Sea coasts) is considered to be a remnant of past glacial epochs and is thus used as proof of the glacial extent. In this paper, we argue that the origin of these tabular ice bodies, which can be used as archives of specific climatic conditions and periglacial environments, is intra-sedimentary (migration/intrusion). The objective of this study is to establish geochemical benchmarks describing the ice formation from atmospheric moisture and compare them with geochemical data of tabular ground ice. Shokalsky glacier on Novaya Zemlya (NZ), on the east coast of the Barents Sea, was chosen as a possible moisture source for the formation of tabular ground ice at the key section ‘Shpindler’ on Yugorsky peninsula, on the south coast of the Kara Sea. Tabular ice in the Shpindler section was compared to the Shokalsky glacier ice in both isotope/geochemical and structural aspects. In general, the hydrochemical properties of glacier ice at NZ and ground ice from Shpindler are closely correlated, while stable-isotope, microelemental and microbiological properties are substantially different. It was concluded that glacier ice most likely participated in the formation of tabular ground ice, but only as a source of refrozen meltwater.

The geometry of glaciers is affected by both the mass balance and the dynamics. We present repeated GPS measurements of longitudinal altitude profiles on three glaciers in Svalbard and show that surface altitude changes alone cannot be used to assess the mass balance. The three measured glaciers are in different dynamic modes, and the observed changes in geometry are strongly affected by the dynamics. Nordenskiöldbreen shows no significant change in the geometry, indicating that the mass balance is in steady state with the dynamics. On Amundsenisen the surface has lowered by 1.5–2.0 ma–1 in the lower part of the accumulation area at 520–550m a.s.l., indicating that the ice flux is higher than the mass-balance input, probably due to a surge advance of the glacier further downstream affecting the higher part of the drainage area. On Kongsvegen the opposite situation was found. Here the geometry of the profile showed a clear build-up of 0.5 ma–1 in the accumulation area and a lowering of 1 ma–1 in the lower part of the ablation area. The ice velocity is very low, giving a negligible vertical velocity component and an ice flux that is far smaller than the mass-balance flux, indicating that the glacier is building up towards a surge advance. Our results show that if mapping of height changes is to be used to monitor the response of the glaciers to climate change, both surface net mass-balance data and dynamic data are needed.

Meltwater intrusions of glacial origin complicate the operation of a coalmine situated approximately 200 m below the bed of Gruvefonna ice cap, Svalbard. The magnitude of this water input is expected to increase with the intended enlargement of the mine. The current praxis, evacuation of the water by pumping, is an expensive undertaking and prompts the investigation of alternative solutions. The evaluation of different options requires reliable values of the total volume and the input rate of the water to be drained. To quantify the melt rate at the glacier surface, we applied a distributed temperature-index model. The model parameters were calibrated using mass-balance measurements performed at Gruvefonna during the 2003 ablation season. The water discharge in the mine during the same period was derived from records of the pump rate. Comparing the records of modelled melt and measured discharge reveals an efficient hydraulic connection between the glacier surface and the mine. The total discharge volume in the mine over the 2003 melt season was about 2.8 × 106m3, exceeding significantly the total melt- and rainwater production on the glacier surface directly above the mine (1.2 × 106m3). This implies that the mine discharge receives contributions from a larger surface area. Based on the distribution of hydraulic potential at the glacier bed, we estimate this contributing area. In a number of scenarios, we calculate the amount of meltwater intrusions for several steps of the planned mine enlargement.