Eliot Glacier is a small (1.6 km2) glacier on Mount Hood, Oregon, USA, and its ablation zone is largely covered with rock debris. We examine the interrelated processes of ablation rates, ice thickness and surface velocities to understand the retreat rate of this glacier. Since measurements began in 1901, the glacier has retreated 680 m, lost 19% of its area and thinned by about 50 m at the lower glacier profile before the terminus retreated past that point. The upper profile, 800m up-glacier, has shown thinning and thickening due to a kinematic wave resulting from a cool period during the 1940s–70s, and is currently about the same thickness as in 1940. Overall, the glacier has retreated at a slower rate than other glaciers on Mount Hood. We hypothesize that the rock debris covering the ablation zone reduces Eliot Glacier’s sensitivity to global warming and slows its retreat rate compared to other glaciers on Mount Hood. Spatial variations in debris thickness are the primary factor in controlling spatial variations in melt. A continuity model of debris thickness shows the rate of debris thickening down-glacier is roughly constant and is a result of the compensating effects of strain thickening and debris melt-out from the ice.

This paper presents a comparative study at a small and highly glacierized catchment area in the Austrian Alps, where runoff under the extreme hot and dry conditions of summer 2003 was simulated based on two different glacier extents: the 2003 glacier extent and the 29% larger 1979 extent. Runoff was simulated applying the hydrological water balance model PREVAH at a high temporal resolution. For this purpose, the catchment area was subdivided into hydrological response units based on digital elevation model and land-cover data. The model was driven by meteorological data from the observatory at Hoher Sonnblick, situated at the highest point of the catchment area (3106ma.s.l.). We were interested in the effect the change in glacier extent would have on the annual and monthly water balance and the hydrograph of hourly discharges. Results of the 2003 and the hypothetical 1979 simulation show main differences in runoff for the period July–August depending on a higher ice-melt contribution. Due to the same meteorological input, both simulations calculate the same snow accumulation and snowmelt. Annual discharge in 1979 would have been 12% higher and hourly runoff up to 35% higher than in 2003.

In order to reconstruct climatic and environmental changes in the Canadian Arctic, an 85 m deep ice core drilled in 1995 on Penny Ice Cap, Baffin Island, was analyzed for ions and δ18O. In addition to the core, snow-pit samples collected in 1994 and 1995 were also analyzed. Elution of ions caused by summer melting was observed in the pits. Due to the heavy summer melting on this ice cap, seasonal variations of ion chemistry and δ18O were not always present in the core. Comparisons of this core with a previously reported core drilled 2.5 maway show that the noise contained in single annual time series is 40–50% for ions and 25% for δ18O. the ice-core data, however, provide us with a reasonable proxy record of climatic and environmental changes during the last two centuries on better than a decadal basis. Sulfate and nitrate concentrations started to increase around 1900 and 1960, respectively, due to anthropogenic influx transported from the industrialized regions in North America. Sea-salt concentrations began to increase around the mid-19th century and were elevated throughout the 20th century. This trend of sea-salt concentrations is similar to that of melt percentage, which is a measure of summer temperature. Warming after the Little Ice Age would have reduced the sea-ice extent and led to the elevated sea-salt concentrations on Penny Ice Cap.

An ice core from the Nevado Huascaran col in the Cordillera Blanca of northern Peru contains high-resolution time series of dust concentrations and size distributions since the end of the last glacial stage. A large dust peak, dated ∼4500 years ago, is contemporaneous with a widespread and prolonged drought that apparently extended from North Africa to eastern China, evidence of which occurs in historical, archeological and paleoclimatic records. This event may have been associated with several centuries of weak Asian/Indian/African monsoons, possibly linked with a protracted cooling in the North Atlantic. During the second half of the 20th century, high austral-summer dust concentrations in the Huascaran record are significantly correlated with atmospheric conditions, such as sea-level pressure and zonal wind velocities that are consistent with El Nino-Southern Oscillation (ENSO) and positive North Atlantic Oscillation (NAO) indices, and with aridity in North Africa, southwest Asia and the Middle East. Therefore, the dominant submicron fraction of the dust may have been transported by more intense northeasterly trade winds from the African dry regions across the tropical Atlantic during a period of frequent and/or intense ENSO activity. The proposed ENSO conditions that may have been linked with drought in the monsoon region may also have contributed to aridity in tropical South America, including the Cordillera Blanca.

We present sea-ice surface roughness estimates, i.e. the standard deviation of relative surface elevation, in the Arctic regions of Fram Strait and the Nansen Basin north of Svalbard acquired by an airborne laser scanner and a single-beam laser altimeter in 2010. We compare the scanner to the altimeter and compare the differences between the two survey regions. We estimate and correct sensor roll from the scanner data using the hyperbolic response of the scanner over a flat surface. Measurement surveys had to be longer than 5 km north of Svalbard and longer than 15 km in Fram Strait before the statistical distribution in surface roughness from the scanner and altimeter became similar. The shape of the surface roughness probability distributions agrees with those of airborne electromagnetic induction measurements of ice thickness. The ice in Fram Strait had a greater mean surface roughness, 0.16 m vs 0.09 m, and a wider distribution in roughness values than the ice in the Nansen Basin. An increase in surface roughness with increasing ice thickness was observed over fast ice found in Fram Strait near the coast of Greenland but not for the drift ice.

The geophysical metronome (Milankovitch components of the past surface temperature variations) and the isotope–temperature transfer function deduced from the borehole temperature profile at Vostok station, Antarctica, are applied to date the 2500 mdeep ice core from Dome Fuji station, Antarctica, and to reconstruct paleoclimatic conditions at the drilling site on the basis of the local δ18O isotope record. Special attention is paid to consistency of this depth–age relation with the mass-balance reconstruction and predictions of ice-flow modeling. the present-day ice mass-balance rate at Dome Fuji is estimated as 3.2 cm a–1. the ice age at the borehole bottom (590m above the bedrock) is around 335 ± 4.5 kyr and may reach 2000 kyr at about 3000 mdepth.The difference in the ice-sheet surface temperatures between Holocene optimum and Last Glacial Maximum is found to be 17.8˚C at the temporal isotope/temperature slope, about 30% lower than the modern geographical estimates. A good agreement between modeled and measured (preliminary data) borehole temperatures is obtained at the geothermal flux 0.059 Wm–2 and ice-fusion temperature (–2˚C) at the ice–rock interface with minimum (zero) melt rates.

Sixteen high-resolution marine aerosol (Na+, SO42–) records from spatially distributed International Trans-Antarctic Scientific Expedition (ITASE) ice cores spanning the last ~200 years from the Pine Island–Thwaites and Ross drainage systems and the South Pole are used to examine sources (sea spray and frost flowers) and transport pathways of marine aerosols into West Antarctica. Factors contributing to the amount of marine aerosols transported inland include sea-ice extent, the presence of open-water features (polynyas, leads), wind strength and direction, and the strength and positioning of low-pressure systems. Analysis of SO42–/Na+ ratios indicates that frost flowers can contribute significantly (40%) to the Na+ budget of Antarctic ice cores. Higher Na+ concentrations in the Ross drainage system may result from greater production of marine aerosols related to frost flowers in the Ross Sea region in association with greater sea-ice extent and larger open-water areas. Significant positive correlations of sea-ice extent and the Na+ time series exist in some regions of West Antarctica. Higher wind speeds in winter and higher Na+ concentrations when sea-level pressure is lower indicate that intensified atmospheric circulation enhances transport and production of marine aerosols.

While measurements of ice-sheet surface elevation change are increasingly used to assess mass change, the processes that control the elevation fluctuations not related to ice-flow dynamics (e.g. firn compaction and accumulation) remain difficult to measure. Here we use radar data from the Thwaites Glacier (West Antarctica) catchment to measure the rate of thickness change between horizons of constant age over different time intervals: 2009–10, 2010–11 and 2009–11. The average compaction rate to ~25 m depth is 0.33 m a−1, with largest compaction rates near the surface. Our measurements indicate that the accumulation rate controls much of the spatio-temporal variations in the compaction rate while the role of temperature is unclear due to a lack of measurements. Based on a semi-empirical, steady-state densification model, we find that surveying older firn horizons minimizes the potential bias resulting from the variable depth of the constant age horizon. Our results suggest that the spatio-temporal variations in the firn compaction rate are an important consideration when converting surface elevation change to ice mass change. Compaction rates varied by up to 0.12 m a−1 over distances <6 km and were on average >20% larger during the 2010–11 interval than during 2009–10.

Recent observations of a decreasing ice extent and a possible thinning of the ice cover in the Arctic make it imperative that detailed studies of the current Arctic environment are made, especially since the region is known to be highly sensitive to a potential change in climate. A continuous dataset of microwave, thermal infrared and visible satellite data has been analyzed for the first time to concurrently study in spatial detail the variability of the sea-ice cover, surface temperature, albedo and cloud statistics in the region from 1987 to 1998. Large warming anomalies during the last four years (i.e. 1995−98) are indeed apparent and spatially more extensive than previous years. The largest surface temperature anomaly occurred in 1998, but this was confined mainly to the western Arctic and the North American continent, while cooling occurred in other areas. The albedo anomalies show good coherence with the sea-ice concentration anomalies except in the central region, where periodic changes in albedo are observed, indicative of interannual changes in duration and areal extent of melt ponding and snow-free ice cover. The cloud-cover anomalies are more difficult to interpret, but are shown to be well correlated with the expected warming effects of clouds on the sea-ice surface. The results from trend analyses of the data are consistent with a general warming trend and an ice-cover retreat that appear to be even larger during the last dozen years than those previously reported.

Along the northern part of the western coast of Sweden, the landscape is characterized by joint-aligned valleys with intervening rock hills. Precambrian bedrock is exposed over large areas and the Quaternary cover is mainly restricted to the bottom of narrow valleys. The well-exposed bedrock exhibits many glacial forms, but recently the major landforms have been interpreted as exhumed sub-Mesozoic etch forms. To gain insight into the relative roles of different processes in shaping the present forms, we studied a granite area where the rock hills contain fractures and narrow clefts with weathering forms and saprolite remnants. Marks of glacial erosion are found only in the upper parts of the clefts, where erosion by subglacial meltwater has exploited weathered preglacial sheeting structures to form furrows with concave cross profiles (p forms). On the summit surfaces, glacial erosion has been of greater importance, but the roche moutonnees found here are also structurally controlled. The main impact of glacial erosion is plucking on the order of tens of metres. Thus, landscapes labelled “areally scoured glacial terrain” can, at some locations, also be described as stripped and slightly incised etch surfaces.

The influence of meteorological variables on snow/ice melting has been analyzed for two very contrasting months, in summer 2006, on Glacier de Saint-Sorlin, French Alps. July 2006 was the warmest July since 1950, and August 2006 was the coldest August since 1979. The total energy available for melting was just over half as much in August as in July, due to a sharp decrease in net shortwave radiation and in turbulent flux. This decrease of net shortwave radiation was mainly controlled by a strong increase in albedo responsible for an increase of reflected shortwave radiation, as well as by a reduction in incident shortwave radiation. During the two months, net longwave radiation remained almost unchanged. The mass balance computed from energy-balance modelling or with a degree-day approach was in good agreement with measured mass balance. Differences were attributed to space and time surface aspect variations which mainly controlled the observed mass balance.

The Norske Øer Ice Barrier (NØIB) is a region of fast ice located off the northeast coast of Greenland. It is one of the most extensive areas of landfast ice on Earth. This paper looks at the NØIB formation during the freeze-up of late 2003 and the break-up in summer 2004. As the fast ice is immobile, it provides an ideal location for checking the consistency of classification schemes for satellite sensors. Active microwave (SAR) backscatter values from Envisat are compared with optical observations from the MODIS, multichannel passive microwave from the SSM/I and with ice-freeboard values from the Envisat RA-2. In August 2004 the underside of the NØIB was mapped by an upward-looking multibeam sonar mounted on the Autosub autonomous underwater vehicle. Statistics from sea-ice draft measurements by the multibeam are compared with near-coincident satellite observations. Evaluating the evolution of the fast ice through multiple satellite sensors with ground truth measurements may allow future development of improved automatic classification algorithms which will be better able to track fast-ice extent. Loss of the fast ice for periods of the year has implications for the coastal environment of Greenland and may contribute to the retreat of the Nioghalvfjerdsfjorden glacier and enhanced coastal erosion.

This paper assesses the capabilities of a new one-dimensional snow scheme developed for the thermodynamic component of the Louvain-la-Neuve sea-Ice Model (LIM). the model is validated at Point Barrow, Alaska, and at Ice Station Polarstern (ISPOL) in the western Weddell Sea, Southern Ocean. the new snow thermodynamic scheme leads to better snow internal temperature profiles, with a set-up-dependent increase in the correlation between simulated and observed temperature profiles. on average over all runs, these correlations are 27% better with the six-layer configuration. the model’s ability to reproduce observed temperatures improves with the number of snow layers, but stabilizes after a threshold layer number is reached. the lowest and highest values for this threshold are 3 (at Point Barrow) and 6 (at ISPOL), respectively. Overall, the improvement of the model’s ability to simulate sea-ice thickness is not as significant as for snow temperature, probably because of the rather crude representation of the snow stratigraphy in the model.

We extrapolate temperature data from a gridded climatology to the equilibrium-line altitude (ELA) of a glacier and tune a degree-day model by adjusting precipitation to give zero mass balance at the ELA. We verify the tuned model by comparing modelled accumulation with winter balance where this has been measured (presently for 180 glaciers). The modelled accumulation naturally depends upon the vertical lapse rate (VLR) for temperature and the degree-day factor (DDF) for snowmelt. Both are somewhat uncertain in high-mountain areas, but modelled accumulation and measured winter balance are in reasonable agreement for most glaciers. The degree-day model predicts a non-linear relation between accumulation and summer temperature at the ELA as assumed by many workers, but we find a family of curves rather than a single universal curve. Maritime glaciers with low annual temperature range have proportionally more accumulation than continental glaciers with high annual temperature range for a similar summer mean temperature. Averages of winter balance for the five main geographical regions where mass-balance data are available agree well with annual accumulation from the degree-day model.

Determining the expected age at a potential ice-core drilling site on a polar ice sheet generally depends on a combination of information from remote-sensing methods, estimates of current accumulation and modelling. This poses irreducible uncertainties in retrieving an undisturbed ice core of the desired age. Although recently perfected radar techniques will improve the picture of the ice sheet below future drilling sites, rapid prospective drillings could further increase the success of deep drilling projects. Here we design and explore a drilling system for a minimum-size rapid-access hole. The advantages of a small hole are the low demand for drilling fluid, low overall weight of the equipment, fast installing and de-installing and low costs. We show that, in theory, drilling of a 20 mm hole to a depth of 3000 m is possible in ∼4 days. First concepts have been realized and verified in the field. Both the drill cuttings and the hole itself can be used to characterize the properties of the ice sheet and its potential to provide a trustworthy palaeo-record. A candidate drilling site could be explored in ∼2 weeks, which would enable the characterization of several sites in one summer season.

Using firn-core data from ten widely spread Antarctic sites, the dependence of firnification on temperature, wind and accumulation rate has been examined with two empirical models. One model relates the square of the porosity to the logarithm of the overburden pressure, and yields good fit to data through the first stage of firnification up to around 0.70-0.75 Mg m −3, beyond which it severely overestimates density. All three meteorological factors enter into this model, with higher temperatures and stronger winds increasing firnification rates, whilst higher accumulation rates have the opposite effect at any given depth. A temperature increase of 10°C has the equivalent effect to a wind-speed increase of 5 m s−1, or an accumulation rate decrease of 0.10 m a−1 w.e. A second model equates the logarithm of the porosity to overburden pressure and gives a much better fit to field data at higher densities where values asymptote to the bubble-free density of pure ice. This model generally yields a poor match to field data in the upper layers, with surface densities generally overestimated. Annual mean wind speed appears to be the least important of the local variables in this case, consistent with the success of the model at greater depth in matching data profiles.

In the Italian Alps, the maximum advance of the Holocene usually coincided with the Little Ice Age (LIA), which reached a climax for most glaciers during the first two decades of the 19th century. Moraines deposited during the peak of the LIA usually obliterated glacial deposits from previous advances. Using dendrogeomorphology, it is possible to date glacier advances before the LIA peak. In the central Italian Alps, it was possible to pinpoint an advance of Ghiacciaio del Madaccio, which took place in the first two decades of the 17th century. With dendrogeomorphology, it is also possible to reconstruct in detail the behaviour of glaciers during the Little Ice Age climax. Trees growing on the margin of glacier tongues may have suffered damage, recognizable by the presence of wood scars and the formation of particularly thin rings; their dating allows both ice advances and retreats to be dated. This is the case for Ghiacciaio Grande di Verra in the western Italian Alps; owing to the rapid decrease of the tree ring widths, it is possible to recognize climate changes responsible for both lower wood production and, sometimes, subsequent glacier advances, although the latter take place with a certain delay. For Ghiacciaio del Lys in the western Italian Alps, a response time of five years was determined.

In shearing sediment beneath glaciers, networks of grains may transiently support shear and normal stresses that are larger than spatial averages. Consistent with studies of fault-gouge genesis, we hypothesize that crushing of grains in such networks is responsible for surrounding larger grains with smaller grains. At sufficiently large strains, this should minimize stress heterogeneity, favor intergranular sliding and abrasion rather than crushing, and result in a self-similar grain-size distribution.

This hypothesis is tested with a ring-shear device that slowly shears a large annular sediment sample to high strains. Shearing and comminution of weak equigranular (2.0–3.3 mm) sediment resulted in a self-similar grain-size distribution with a fractal dimension that increased with shear strain toward a steady value of 2.85. This value is significantly larger than that of gouges produced purely by crushing, 2.6, but it is comparable to values for tilts thought to be deforming beneath modern glaciers, 2.8 to nearly 3.0. At low strains, under a steady mean normal stress of 84 kPa, variations in normal stress measured locally ranged in amplitude from 50 to 300 kPa with wavelengths that were 100 times larger than the initial grain diameter. Crushing of grains, observed through the transparent walls of the device, apparently caused the failure of grain networks. At shearing displacements ranging from 0.7 to 1.0 m, the amplitude of local stress fluctuations decreased abruptly. This change is attributed to fine sediment that distributed stresses more uniformly and caused grain networks to fail primarily by intergranular sliding rather than by crushing of grains. Sliding between grains apparently produced silt by abrasion and resulted in a fractal dimension that was higher than if there had been only crushing.

A size distribution with a fractal dimension greater than 2.6 is probably a necessary but not sufficient condition for determining whether a basal till has been highly deformed. Stress heterogeneity in subglacial sediment that is shearing through its full thickness should contribute to the erosion of underlying rock.

This paper summarizes the 37 year history of net accumulation measurements at the geographic South Pole obtained by numerous investigators using a variety of techniques. These data lead to the conclusion that annual net snow accumulation has increased in the vicinity of South Pole Station (SPS) since 1955. The records were examined for evidence of a “station effect” and it is concluded that not all of the observed increase can be attributed to snow drift associated with the presence of the station. Furthermore, the accumulation increase at the South Pole appears consistent with increases observed at other locations on the East Antarctic Plateau, and in the Peninsula region as well. These data suggest that the recent accumulation increase at SPS may be regionally extensive over the East Antarctic Plateau.

The Chinese National Antarctic Research Expedition (GHINARE) carried out three traverses from Zhongshan station to Dome A, Princess Elizabeth Land and Inaccessible Area, East Antarctic ice sheet, during the 1996/97 to 1998/99 Antarctic field seasons. The expeditions are part of the Chinese International Trans-Antarctic Scientific Expedition program. In this project, glaciological investigations of mass balance, ice temperature, ice flow, stratigraphy in snow pits and snow/firn ice cores, as well as the glaciochemical study of surface snow and shallow ice cores, have been carried out. In the 1998/99 field season, CHINARE extended the traverse route to 1128 km inland from Zhongshan station. The density profiles show that firnification over Princess Elizabeth Land and Inaccessible Area (290–1100 km along the route) is fairly slow, and the accumulation rate recovered from snow pits along the initial 460 km of the route is 4.6–21 cm (46–210 kg m–2a–1 ) water equivalent. The initial 460 km of the route can be divided into four sections based on the differences of accumulation rate. This pattern approximately coincides with the study on the Lambert Glacier basin (LGB) by Australian scientists. During the past 50 years, the trends of both air temperature and accumulation rate show a slight increase in this area, in contrast to the west side of the LGB. Data on surface accumulation rates and their spatial and temporal variability over ice-drainage areas such as the LGB are essential for precise mass-balance calculation of the whole ice sheet, and are important for driving ice-sheet models and testing atmospheric models.