Since the Little Ice Age, most glaciers in the Tien Shan mountains have been retreating. Owing to an increase in precipitation in most parts of the mountains during the late 1950s to early 1970s, the percentage of receding glaciers and the speed of retreat have tended to decrease in the 1970s. However, the general trend of continuous glacier retreat remains unchanged, in part because the summer air temperature shows no tendency to decrease.

In the Tien Shan mountains, as the degree of climatic continentality increases the mass balance becomes more dependent on summer temperature, and accumulation and ablation tend to be lower. Therefore, the responses of glaciers to climatic fluctuations in more continental areas are not synchronous with those in less continental areas, and the amplitude of the glacier variations becomes smaller.

The rapid retreat and disintegration of the Larsen Ice Shelf sector extending north of Seal Nunataks (65° S), documented from the mid 1970s onwards by remote sensing, is presented and related to the Antarctic Peninsula climatic warming recorded over several past decades. A 1975 KOSMOS satellite photograph and a series of LANDSAT MSS and TM images taken in 1978, 1979, 1986, 1988 and 1989 were used to monitor the retreat of the ice shelf between Seal Nunataks and Prince Gustav Channel. The ice shelf has decreased by more than 30% during the period 1975–89 within the Christensen Island to Cape Longing region. Measurements of the ice front position carried out in the field during late 1991 indicate that the recession between Lindenberg Island and Sobral Peninsula is still continuing, in some places at a rate of up to 2.5 km a−1.

Piston cores collected from the Ross Sea continental shelf, Antarctica, were studied as part of a multi-scale analysis of glacial and glaciomarine stratigraphy and sedimentology. The objective of these analyses was to differentiate glaciomarine sediments from subglacially deformed tills. Results from analyses of microstructures, lithofacies and seafloor morphology indicate that glaciomarine and subglacially deformed sediments can be clearly distinguished and further characterized by variations in textural parameters. Overcompaction, as well as presence of stratification in sediments, are not considered critical criteria for distinguishing subglacial from glaciomarine deposits. Trough-shaped morphologies and fluted terrain strongly correlate with S-C and S-C-C- type shear-zone microstructures and indicate that subglacial deformation is an important process in these areas, confirming the presence of grounded ice on the shelf during formation of these landforms and deposits. Flat, smooth topographies, as well as (low-angle) slope environments, correspond to microfabrics which lack microscopic shear-zone geometries and contain dropstones, angular-sediment clasts, large-shell fragments and slight sorting in sandy layers, which imply ice-shelf or open-water conditions present during deposition.

Spectrofluorimetric and spectrophotometric continuous flow analysis (CFA) methods were developed and applied to the determination of aluminium and iron in EPICA Dome C (East Antarctica) ice-core samples (6–585m depth). The methods are able to measure the fraction of Al and Fe which can be detected once the sample is filtered on a 5.0 μm membrane and acidified to pH 2. Both the methods present high sensitivity (detection limit of 10 ng L–1 for Al and 50 ng L–1 for Fe) and reproducibility (5% at sub-ppb level). The Fe and Al profiles show sharp decreases in concentrations in the last glacial/interglacial transition, reflecting the decreasing dust aerosol load. The two elements show a different pattern during the Antarctic Cold Reversal (ACR) climatic change, with high iron concentrations (similar to the glacial period) and low but increasing Al content during the ACR minimum. In order to interpret the Al and Fe data obtained by CFA, a comparison with Al and Fe composition, as measured by inductively coupled plasma sector field mass spectrometry (ICP-SFMS), was performed for Holocene, ACR and glacial periods. The percentage of CFA-Al with respect to ICP-SFMS-Al in the three periods shows a lower variability than CFA-Fe (3% in the glacial period and 64% in the ACR). This pattern may be explained by the different dominant iron sources in the different climatic periods. During the Last Glacial Maximum, Fe is proposed to arise mainly from insoluble continental dust, while a variety of ocean-recycled Fe, mainly distributed in fine particles and as more soluble species, shows a higher contribution in the ACR and, to a lesser extent, in the Holocene.

A physically based computational model of drifting snow in two-dimensional terrain is developed. The model considers the case where wind speeds are low enough to neglect the transport of particles from the saltation layer into the turbulent flow field. The model has two distinct parts, one describing the turbulent airflow, and a second describing the mass-transport process and resulting snow-accumulation patterns produced by saltation transport. The turbulent-flow model consists of a general solution of the time-averaged, two-dimensional Navier-Stokes equations, where the k-∊ turbulence model is used to close the system of equations. The turbulent-flow model is coupled to a saltation model to compute the time evolution of the surface wind fields and snowdrift formation in the vicinity of a solid fence. Modeled wind fields and snow-accumulation profiles are similar to published field and experimental data.

The friction of pure ice against various materials was studied at the melting point by pulling plates of the materials of known roughness under a melting ice sample, which was loaded from above, and by maintaining a surrounding air temperature of +2°C (±1°C). Speed was varied over a wide range from 0.05 to 400 mm s−1.

Results for an aluminium sheet of roughness Ra = 0.84 μm, showed a maximum in friction coefficient of 0.04 at a speed of 16 mm s−1. Below this speed the friction coefficient dropped to 0.002 at 0.2 mm s −1 and results from different ice samples were very reproducible. Above 16 mm s−1, the friction coefficient initially dropped to about 0.002 at 100 mm s−1, and then increased again to 0.037 at 400 mm s−1. Results at speeds above 16 mm s−1 were much less reproducible than those at lower speeds. Results are given also for the friction of ice on Formica, acrylic, and copper plates.

The amount of meltwater produced during a test was measured by weighing an absorbent tissue before and after mopping-up the meltwater. The amount of meltwater was significantly more for aluminium than for Formica or acrylic, showing that the thermal conductivity of the slider was controlling the amount of meltwater. The amount was also a strong function of velocity.

The hypothesized link between glacier surging and bedrock geology motivates this study of the suspended sediment size distributions (SSSD) from surge-type and non-surge-type glaciers. We analyze SSSDs from proglacial streams in 20 individual basins comprising various fractions of metasedimentary (MS) and felsic plutonic rocks. We compare the size distributions by performing tests of significance on the distribution statistics, and a principal component analysis on discrete grain sizes. We find that surge-type and non-surge-type glaciers underlain solely by MS rocks have significantly different SSSDs, while surge-type glaciers as a whole have remarkably similar SSSDs, regardless of the underlying bedrock geology. These observations hint at a relationship between sediment characteristics and glacier surging, though causation in either direction cannot be established without additional data.

Moraines in five valleys of the Turkestan range of the Pamir-Alay, Kyrgyz Republic, were analyzed based on their geographical position and elevation, morphology and ecological characteristics. The moraines represent four glacial advances: Turkestan Stage I, during the last glacial; Stage II, during the late Holocene; Stage III, during the Little Ice Age (AD 1400−1900); and Stage IV, during the 20th century. In Turkestan Stage I, the glaciers expanded to about 5−10 km from their present termini during marine isotope stage (MIS) 2. Radiocarbon ages for several soil layers buried in a lateral moraine of the Asan-Usin glacier frontal area indicate that glaciers shrank or stagnated between at least ∼48 and 42 kyr BP, during the warm climate of mid-MIS 3. These findings suggest that the glacier expansion in mid-MIS 3 was relatively small compared to the glacier expansion of MIS 2 during the last glacial.

Supraglacial streams form annually during the melt season, transporting dissolved solutes from the melting ice and snowpack to subglacial flow paths and the glacier terminus. Although nutrient and carbon processing has been documented in other supraglacial environments (cryoconite holes, snowpack), little work has examined the potential for in-stream nutrient retention in supraglacial streams. Here we carried out a solute nutrient injection experiment to quantify NH3+, PO43− and labile dissolved organic carbon (DOC) retention in a supraglacial stream. The experiment was performed on a 100 m stream reach on Mendenhall Glacier, an outlet glacier on the Juneau Icefield, southeastern Alaska, USA. The study stream contained two distinct reaches of equal length. The first reach had a lower velocity (0.04 ms−1) and contained abundant gravel sediment lining the ice–water interface, while the second reach was devoid of bedload sediment and had an order-of-magnitude higher velocity. At the end of the second reach, the stream emptied into a moulin, which is typical of supraglacial streams on this and other temperate glaciers. We found that N and P were transported largely conservatively, although NO3− increased along the reach, suggestive of nitrification. Labile DOC was retained slightly within the stream, although rates were low relative to the travel times observed within the supraglacial stream. Although our findings show that these streams have low processing rates, measurable in-stream nitrification and dissolved organic matter uptake within this biologically unfavorable environment suggests that supraglacial streams with longer residence times and abundant fine substrate have the potential to modify and retain nutrients during transport to the glacier terminus.

We present results from a laboratory tank study of ice growing from saline water in a wave field, focusing on the transition from a predominantly frazil/grease-ice cover to a pancake-ice cover. Combining surface temperature observations with direct and indirect determinations of ice salinity and solid fraction, we describe the evolution of frazil- and pancake-ice area fraction, salinity and solid-ice volume fraction over the course of 1 day. In the investigated stage of transition, frazil ice surrounding the pancakes was found to have rather constant properties: a surface temperature 0.4–0.6 K below the freezing point of the underlying sea water, a salinity of 24–26 g kg–1 and a solid volume fraction of 0.25–0.29. the average salinity of young pancake ice, estimated from heat and salt budgets, decreased from 18 to 15 g kg–1, while average solid volume fractions increased from 0.6 to 0.7. the transition from frazil to pancake is estimated to take place when solid fractions reach 0.37–0.40 and surface temperatures are 0.7–0.9 K below the freezing point. We find that, for proper modelling of the grease–pancake system, it is important to distinguish between a surface and volumetric fraction of pancakes and grease ice.

Aerial photography and satellite imagery of the Petersen ice shelf, Nunavut, Canada, from 1959 to 2012 show that it was stable until June 2005, after which a series of major calving events in the summers of 2005, 2008, 2011 and 2012 resulted in the loss of ∼61% of the June 2005 ice-shelf area. This recent series of calving events was initiated by the loss of extensive regions of ˃50-year-old multi-year landfast sea ice from the front of the ice shelf in summer 2005. Each subsequent calving event has been preceded by open-water conditions and resulting loss of pack-ice pressure across the front of the ice shelf, and most occurred during record warm summers. Ground-penetrating radar (GPR) ice thickness measurements and RADARSAT-2 derived observations of surface motion indicate that tributary glaciers provided total ice input of 1.19-5.65 Mta–1 to the ice shelf from 2011 to 2012, far below the mean surface loss rate of 28.45 Mta–1. With recent losses due to calving and little evidence for current basal freeze-on, this suggests that the Petersen ice shelf will no longer exist by the 2040s, or sooner if further major calving events occur.

Computations over 50 000 years into steady state with Greve’s polythermal ice-sheet model and its numerical code are performed for the Greenland ice sheet with today’s climatological input (surface temperature and accumulation function) and three values of the geothermal heat flux: (42, 54.6, 29.4) mW m−2. It is shown that through the thermomechanical coupling the geometry as well as the thermal regime, in particular that close to the bed, respond surprisingly strongly to the basal thermal heat input. The most sensitive variable is the basal temperature field, but the maximum height of the summit also varies by more than ±100m. Furthermore, some intercomparison of the model outputs with the real ice sheet is carried out, showing that the model provides reasonable results for the ice-sheet geometry as well as for the englacial temperatures.

We describe a derivation of surface velocities and associated errors for Black Rapids Glacier, Alaska, U.S.A., using single-orbital-path synthetic aperture radar interferometry (InSAR). The technique described is adapted to small temperate glaciers with complex flow patterns. We also describe a motion anomaly, apparent in the InSAR phase signal, that persisted on Black Rapids Glacier for at least 78 days during winter 1991/92 and recurred in 1996. This anomaly is interpreted using a basal hydrology hypothesis in which a hydraulic head is maintained at the glacier bed at close to the overburden pressure. This permits a cumulative influx of 1.6 × 106 m3 of water under the glacier, a sort of shallow subglacial lake, that migrates downstream at an average rate of 30 m d− 1 over 78 days. The motion anomaly is speculated to be an unsuccessful bid for surge initiation.

Recent drilling successes on Rutford Ice Stream in West Antarctica demonstrate the viability of hot water drilling subglacial access holes to depths >2000 m. Having techniques to access deep subglacial environments reliably paves the way for subglacial lake exploration beneath the thick central West Antarctic Ice Sheet. An ideal candidate lake, overlain by ~2650 m of ice, identified by Centro de Estudios Científicos (CECs), Chile, has led to collaboration with British Antarctic Survey to access Subglacial Lake CECs (SLCECs). To conform with the Scientific Committee on Antarctic Research code of conduct, which provides a guide to responsible scientific exploration and stewardship of these pristine systems, any access drilling must minimise all aspects of contamination and disturbance of the subglacial environment. To meet these challenges, along with thicker ice and 2000 m elevation, pumping and water treatment systems developed for the Subglacial Lake Ellsworth project, together with new diesel generators, additional water heating and longer drill hose, are currently being integrated with the BEAMISH hot water drill. A dedicated test season near SLCECs will commission the new clean hot water drill, with testing and validation of all clean operating procedures. A subsequent season will then access SLCECs cleanly.

Several years of daily microwave satellite ice drift are combined with moored upward-looking sonar (ULS) ice drafts into an ice-volume flux record at points along a flux gate across the Weddell Sea, Antarctica. Monthly ice transport varies at the mooring locations from a maximum export of 0.4 m3 s−1 near joinville Island to −0.4 m3 s−1 imported along the Fimbul and Riiser-Larsen ice-shelf margins. Winter peaks are observed at each end of the flux gate, where high concentrations of deformed ice are advected in and out of the basin along the coastline. The central gyre, in contrast, exhibits negligible seasonality and much smaller volume transports. During the period of overlapping ULS operation, the mean monthly integrated ice export west of the gyre center is 59 × 103 m3 s−1, and the import in the East Wind Drift is −17 x103 m3s-1. ULS data are compared with ERS satellite observation of radar backscatter to obtain an empirical relationship between ice thickness and the rate of change of backscatter with incidence angle. Resulting proxy ice-thickness data are combined with Special Sensor Microwave/Imager-derived ice velocities to obtain seasonally varying estimates of net ice-volume flux for the period 1992−98. Significant interannual variability is observed in ice-volume flux expressed as fresh-water transport. A maximum annual mean of 0.054 Sv is observed in 1992; with a minimum of 0.015 Sv in 1996. A 6 year mean transport of 0.032 Sv is observed. Maximum seasonal ice export occurs in July 1992, with a minimum in November 1996. The 10 year mean area flux is 30 × 103 m2s–1 Interannual variations in net volume flux closely follow variations in area flux, with summer minima in 1990/91 and 1996/97. Maximum area transport occurs in 1991, and although this predates the ERS-1 scatterometer data, ice-thickness estimates by Harms and others confirm 1991 as a decadal peak in net integrated fresh-water transport.

A degree-day model extended for surface mass-balance calculations has been applied to derive the sensitivity of Gran Campo Nevado ice cap (GCN), southwest Patagonia, to climate change. Seasonal sensitivity characteristics were computed using automatic weather station data gathered in the period 2000–05. Results indicate pronounced mass-balance sensitivity to temperature during the summer, with monthly values of –0.27±0.01mw.e. K–1. Monthly sensitivity to a 10% precipitation perturbation fluctuates around +0.03mw.e The sensitivity characteristics obtained were used to model the surface mass-balance evolution of GCN during the 20th and 21 st centuries based on monthly means of air temperature and precipitation derived from bias-corrected weather station data and statistically downscaled re-analysis and general climate model data. Surface mass balance shows a persistently negative trend ranging from around +1mw.e. a–1 at the beginning of the 20th century down to almost –1.5mw.e. a–1 during the first years of the 21st century, with only a few positive years occurring occasionally during the second half of the 20th century. The scenario for the end of the 21 st century totals approximately –4.5mw.e. a–1, i.e. an estimated ice volume loss for GCN of 59 km3 during 1900–2099.

The water balance of the mountainous Durance river catchment, French Alps, is simulated from 1981 to 1994 with a soil-vegetation-atmosphere transfer (SVAT) model. Particular attention is paid to the snow-cover evolution using a detailed model of the snowpack evolution. The results are validated by comparison of the simulated discharges calculated by the SVAT with daily observations at three gauging stations located in the watershed. Three different spatial resolutions are used (1, 8 and 46 km) in order to evaluate the impact on the surface-water-budget results. Comparison with the finest resolution indicates the need for sub-grid-scale parameterization for the model with larger resolution.

An experimental program at Worthington Glacier, Alaska, U.S.A., has yielded the first in situ measurement of the full stress tensor in glacier ice. Measurements were made with an array of stiff (low-compliance) normal-force sensors frozen into a borehole at 120 m depth. Freezing in temperate ice was accomplished by a down-hole heat exchanger which extracted heat at a rate of 15 W. Under slowly varying stress conditions, relaxation of stress anomalies by viscous creep following drilling of the hole and installation of the sensors allows for equilibration of measured stresses with far-field stresses. Equilibration of local and far-field stresses was confirmed and pressure sensors calibrated in laboratory experiments prior to the field program. Results of the stress measurements show principal axes of the stress tensor oriented in directions consistent with the geometry of the glacier and broadly consistent with measured englacial strain rate. The magnitudes of stress-tensor components are more error-prone and more sensitive to uncertainty in sensor magnitude than uncertainty in sensor orientation. Mean stress determined by pressure measurements agrees with estimated lithostatic overburden to within approximately 15%. Unexpected results include a stress perturbation lasting about 5 days that caused a rotation of the orientations of the principal stress axes of approximately 5° about an axis pointing in the down-flow direction.

The shortwave albedo is a major component in determining the surface energy balance and thus the evolution of the spring melt cycle. As the melt commences, the ice is partitioned into multiple surface types ranging from highly reflective white ice to absorptive blue ice. The reflectance from these surfaces shows significant spatial and temporal variability. Spectral albedo measurements were made at six different sites encompassing these two surface types, from 19 March to 3 May 2005, on 1.5 m thick landfast sea ice in southwestern Hudson Bay, Canada (58˚ N). Furthermore, the broadband albedo and the surface energy balance were continuously recorded at a nearby site during the 1 month period. Rapid changes in the albedo were found to relate to typical subarctic climate conditions, i.e. frequent incursions of southerly air, resulting snow and rain events and the generally high maximum solar insolation levels. Subsequently, diurnal variations in snow surface temperature were evident, often causing daytime melting and night-time refreezing resulting in the formation of ice lenses and superimposed ice. After rain events and extensive melting, the snowpack was transformed throughout into melt/freeze metamorphosed snow and superimposed ice. The integrated (350–1050 nm) albedo varied between 0.52 and 0.95 at the blue-ice sites, while it varied between 0.73 and 0.91 at white-ice sites. Variability on the order of ±10% in the white-ice broadband albedo resulted from the diurnal freeze–thaw cycle, but also synoptic weather events, such as snowfall and rain events, could rapidly change the surface conditions.

Measurements made on first-year ice in the Arctic and sub-Arctic are used to show that ice from both regions decays in a similar manner during the spring/summer melt season. One notable difference is that melt-induced changes in sub-Arctic Labrador occur about 2 months earlier than in the Arctic. In both regions, the temperature and strength of the ice change gradually over the season, whereas the bulk salinity and thickness of the ice do not change substantially until later in the season, when the ice becomes isothermal at a temperature of –1.8˚C. Results show that the seasonal decrease in the strength of first-year sea ice and the temperature-induced increase in brine volume are correlated. Once the ice is devoid of salt in late summer, the air volume continues to increase but has minimal effect on the ice strength.