The surface flooding of Antarctic sea ice in summer covers 50% or more of the sea-ice area in the major summer ice packs, the western Weddell and the Bellingshausen-Amundsen Seas. Two CRREL ice mass-balance buoys were deployed on the Amundsen Sea pack in late December 2010 from the icebreaker Oden, bridging the summer period (January–February 2011). Temperature records from thermistors embedded vertically in the snow and ice showed progressive increases in the depth of the flooded layer (up to 0.3–0.35 m) on the ice cover during January and February. While the snow depth was relatively unchanged from accumulation (<10 cm), ice thickness decreased by up to a meter from bottom melting during this period. Contemporaneous with the high bottom melting, under-ice water temperatures up to 1°C above the freezing point were found. The high temperature arises from solar heating of the upper mixed layer which can occur when ice concentration in the local area falls and lower albedo ocean water is exposed to radiative heating. The higher proportion of snow ice found in the Amundsen Sea pack ice therefore results from both winter snowfall and summer ice bottom melt found here that can lead to extensive surface flooding.

Data from ice rises on the east coast of the Antarctic Peninsula can be interpreted as showing that the ice is thinning at rates of up 0.5 m a−1. However, a level line between two nunataks in Palmer Land showed no change in surface elevation over a period of 5 a. Melt rates on George VI Ice Shelf vary with position and may indicate that parts of the ice shelf are thickening at the rate of several m a−1, presumably in response to a higher accumulation rate over the peninsula a few hundred years ago. A small valley glacier, Spartan Glacier, is wasting away at about 0.27 m a−1. Ice fronts on both east and west coasts of the peninsula have been retreating for the last 30 a. It seems that there is general glacier recession in response to a wanner climate and decreased snowfall for at least the last 30 a, while parts of the peninsula are still thickening in response to a high accumulation rate several hundred years ago.

Ice cores recovered for paleoclimatic and/or paleoenvironmental reconstructions in the Tien Shan and Qinghai–Tibetan Plateau often encounter cracks. Although we expect that cracks opened to surface meltwater will inevitably change ice-core records, we do not know how and to what extent records are influenced. An ice core retrieved from glacier No. 1 at Ürümqi river head, Tien Shan, China, exhibits a crack nearly 2.5 m long that has admitted meltwater, forming secondary ice within the fracture. A small inclusion of the infiltrated ice in sampling is shown to reduce δ18O by an extent of Holocene vs Last Glacial Maximum while enhancing significantly the pH, conductivity and the following ionic species: CH3COO–, and CO(COO)22–. of the parameters increased, and HCOO– are the most affected, being enhanced nearly six-fold in the fractured section compared to the non-fractured sections, followed by CO(COO)22– and electrical conductivity measurement (ECM). Despite the alteration, primary fluctuations of some parameters are still recognizable. This suggests that if the infiltrated ice can be avoided in the sampling operation, ice cores with cracks may still provide authentic records. This shows the need to pay close attention to physical characteristics of ice cores in order to identify such secondary ice.

High-resolution numerical model experiments were carried out along two flowlines in Dronning Maud Land, Antarctica, one flowline passing through the central part of a coastal mountain range and the other along a major continental ice stream (Shirase Glacier). Results showed that ice-sheet behaviour in response to the climatic signal differs locally. Response patterns are different for the inland ice sheet, for the coastal ice sheet and around marginal (subglacial) mountains. Modelled response time series were analyzed by lag-correlation, range and fractal analysis. Local differentiation in ice-sheet response is primarily related to the sensitive interplay between surface accumulation patterns, thermomechanical properties of the ice sheet and bedrock roughness.

As the focus of intensive glaciological studies in the 1960–70s, White Glacier on Axel Heiberg Island, Canada, has played an important role in understanding the dynamics of mostly-cold polythermal glaciers in the high Arctic. In this study, we examine the magnitude, duration and timing of peak velocity events in the summers of 2013–15 using continuous dual-frequency GPS observations, and compare them with similar measurements made in 1968. Summer speed-up events in 1968 and 2014, in which ice velocities reached 200% above winter values, were found to occur in conjunction with formation and drainage of an ice-marginal lake. Despite thinning of the glacier by >20 m and a decrease in annual surface velocities of 15–35% since the 1960s, the relative magnitude and duration of these peak events has increased, particularly at lower elevations, in comparison with the observations at the same locations many decades ago. Given the long-term slowdown of the glacier, the relative contribution of summer displacement to the net annual motion has therefore increased significantly, with summer motion over the span of <2 months now accounting for nearly half of the total annual displacement.

Several sets of temperature measurements were carried out in 1972- 88 in the Vostok boreholes. They have provided the ice-sheet temperature profile down to a depth of 2000 m. The accuracy of the profile is sufficient to analyze perturbations induced by the surface-temperature variations over the last climatic cycle. The mathematical model developed for the ice-temperature computation is applied to solve an inverse problem. The amplitudes and phase lags of the main harmonic components in the surface-temperature variations are reconstructed on the basis of fitting the calculated ice-temperature profile to the experimental one with the assumption that Milankovich's cycles (100, 41, 23 and 19 kyear) are dominant in the climate oscillations. The paleotemperature record simulated with the inverse procedure is revealed to be insensitive to the model parameters varied within the range of their uncertainty. Minimal standard deviation between calculated and measured temperature profiles is found of the same order as the reproducibility of the temperature measurements (0.005-0.01°C). Although the simulated temperature-time curve obtained in this study does not contain short-term variations, all the main climate events predicted from the ice-core isotope analysis can be recognized. Thus, the age of the events can be verified independently of the ice-sheet dynamics dating. The resultant time-scale for the Vostok record appears to be in good agreement with the dating of climate events recorded in deep-sea sediments.

Sensitivity experiments can be used to illustrate the response of the general circulation to prescribed changes in lower boundary conditions (such as ocean temperature) or external forcing conditions (such as solar radiation). The climatic record from the late-glacial and the Holocene provides examples for both types of prescribed change experiments. A number of general circulation model experiments have been carried out. These are reviewed.

At 18 ka 8P, orbital parameter values were very much like those of today, but the lower boundary conditions (ocean temperature, ice-sheet extent, etc.) were very different. The change in ocean temperature, and ice-sheet extent and thickness, were prescribed from the results of the Climate: Long-range Investigation Mapping and Prediction (CLIMAP) project.

At 9 ka BP, orbital parameter values were very different from present, leading to increased radiation in July and decreased radiation in January (compared to present). The North American ice sheet still covered a significant area, so that lower boundary conditions also differed from the present ones. The combined and individual effects of these prescribed changes on the general circulation are reviewed, particularly in the context of changes of the monsoon circulation.

At 6 ka BP, the solar radiation distribution differed from that of today in much the same fashion as at 9 ka BP, although the magnitude of the change was reduced. Lower boundary conditions were probably very similar to those of today.

A series of experimental results from 18, 9, and 6 ka BP are presented as “snapshot” estimates of the paleoclimate of those times. The results are based upon simulations with the community climate model of the National Center for Atmospheric Research.

A model of the Antarctic ice sheet has been used to simulate the ice sheet in warmer climates, in order to investigate what kind of ice-sheet geometries one can reasonably expect under what kind of climatic conditions and to discover which physical mechanisms may be involved to explain them. The results of these experiments reveal the considerable stability of; in particular, the East Antarctic ice sheet. It would require a temperature rise of between 17 and 20 K above present levels to remove this ice sheet from the subglacial basins in the interior of the continent and of 25 K to melt down the Antarctic ice sheet completely. For a temperature rise below 5 K, the model actually predicts a larger Antarctic ice sheet than today as a result of increased snowfall, whereas the west Antarctic ice sheet was round not to survive temperatures more than 8–10 K above present values. Furthermore, basal temperature conditions in these experiments point to the problems involved in raising the base of the ice sheet to the pressure-melting point over the large areas necessary to consider the possibility of sliding instability. These results bear on a lively debate regarding the late Cenozoic glacial history of Antarctica. Particularly, based on these findings, it is difficult to reconcile a highly variable East Antarctic ice sheet until the Pliocene with modest warming recorded in, for instance, the deep-sea records for the late Neogene.

Soviet plans to divert water from rivers flowing into the Arctic Ocean have led to research into the impact of a reduction in discharge on Arctic sea ice. We consider the mechanisms by which discharge reductions might affect sea-ice cover and then test various hypotheses related to these mechanisms. We find several large areas over which sea-ice concentration correlates significantly with variations in river discharge, supporting two particular hypotheses. The first hypothesis concerns the area where the initial impacts are likely to which is the Kara Sea. Reduced riverflow is associated occur, with decreased sea-ice concentration in October, at the time of ice formation. This is believed to be the result of decreased freshening of the surface layer. The second hypothesis concerns possible effects on the large-scale current system of the Arctic Ocean and, in particular, on the inflow of Atlantic and Pacific water. These effects occur as a result of changes in the strength of northward-flowing gradient currents associated with variations in river discharge. Although it is still not certain that substantial transfers of riverflow will take place, it is concluded that the possibility of significant cryospheric effects and, hence, large-scale climate impact should not be neglected.

We conducted a 9-d seismic experiment in October 2015 at Laohugou Glacier No. 12. We identified microseismic signals using the short-term/long-term average trigger algorithm at four stations and classified them as long and short-duration events based on waveform, frequency, duration and magnitude characteristics. Both categories show systematical diurnal trends. The long-duration events are low-frequency tremor-like events that mainly occurred during the daytime with only several events per day. These events lasted tens of seconds to tens of minutes and are likely related to resonance of daytime meltwater. The dominant short-duration events mostly occurred during the night time with a peak occurrence frequency of ~360 h−1. Their short-duration (<0.2 s), high frequency (20–100 Hz) and dominance of Rayleigh waves are typical of events for near-surface crack opening. A strong negative correlation between the hourly event number and temperature change rate suggests that the occurrence of night-time events is controlled by the rate of night-time cooling. We estimated the near-surface tensile stress due to thermal contraction at night to be tens of kilopascals, which is enough to induce opening of surface cracks with pre-existing local stress concentrations, although we cannot exclude the effect of refreezing of meltwater produced during the day.

The glaciological structure and dynamics of West and Shackleton Ice Shelves, East Antarctica, are qualitatively determined using a combination of satellite remote-sensing techniques. Sketch maps traced from unenhanced imagery show the ice edge, grounding lines, flow lines, and rifts. Surface-elevation profiles and contour maps from radar altimetry provide free-board elevations of the floating ice and show flow-line undulations and rumples characteristic of grounded ice. West and Shackleton Ice Shelves consist of a combination of fast-moving ice tongues from outlet glaciers and slow-moving parts constrained by islands, ice rises, and ice rumples.

The numerical solution to a time-dependent two-dimensional problem of an avalanche impact against a wall is presented. The height of the wall is much larger than the flow depth. Compressibility of the moving snow as well as the effect of gravity is taken into account. Calculations are made for an impact of low-density avalanches with densities <100 kgm–3 obeying the equation of state for a mixture of two gases (air and gas of ice/snow particles). The pressure, density and velocity distributions in the flow as functions of time and space coordinates are calculated, as well as the variation of the flow depth. In particular, the flow height at the wall, the pressure at the wall and the pressure distribution on the slope near the wall are given, demonstrating peaks and falls due to compression shocks and rarefaction waves.

Although the effects of snow during sea-ice growth have been investigated for sea ice which is thick enough to accommodate dry snow, those for thin sea ice have not been paid much attention due to the difficulty in observing them. Observations are complicated by the presence of slush and its subsequent freeze-up, and the surface heat budget might be sensitive to the additional ice thickness. An onsite short-term land fast sea-ice freeze-up experiment in the Saroma-ko Lagoon, Hokkaido, Japan was carried out to examine the effects of snowfall on the structure and surface heat budget of thin sea ice, based on observational results and a 1-D thermodynamic model. We found that snowfall contributes to the solidification of the surface slush layer, contributing ice thickness that is comparable to the snowfall amount and affecting the crystal texture significantly. On the other hand, the basal ice growth rate and turbulent heat flux were not significantly affected, being <3.1 × 10−8 m s−1 and 3 W m−2, respectively. This finding may validate the omission in past studies of snow effect in estimating ice production rates in polynyas and has implications about the reconstruction of growth history from sample analysis.

Questionnaires concerning slush flows were distributed globally. The purpose of the questionnaire was to determine the geographic distribution of slush-flow activity and also to collect information concerning the most commonly used nomenclature, release conditions, the season of occurrence, the type of terrain most susceptible to slush-flow occurrences, the characteristics of starting zones, paths and run-out zones, geomorphic activity, type of damage likely to result, and hazard control.

Individuals having first-hand experience of the slush-flow process have been identified. The answers to the questionnaire established that slush flows definitely occur in lower latitudes as well as in the Arctic, and that the slush-flow hazard has not yet received the emphasis that it deserves. Heavy rainfall may cause slush flows at any time during winter, especially in areas with a marine west-coast type of climate. Stream channels and shallow depressions are the most common locations of starting zones, while slush-flow frequency seems to be closely related to the permeability of the substratum. Slush flows are a significant geomorphic agent, and it is noteworthy that there has been an increasing encroachment into potential slush-flow zones as a consequence of human activity.

In this paper, we present an electric-thermal drill with a novel design of a melting head that was developed within the EnEx-RANGE project. The design combines a short melting head with a large surface area of parabolic shape. It was succesfully tested in the laboratory as well as on Alpine glaciers (Langenferner and Mittelbergferner) and at the Ross Ice Shelf in Antarctica. In all these different environments, a high melting speed per specific power of typically 8.8 cm3 w−1 h−1 is achieved that is close to the ideal maximum bound of ~10.5–11.8 cm3 w−1 h−1 when neglecting all heat losses. It has also been demonstrated that the melting probe can be operated with typical equipment of small-scale field camps including a small power generator.

From field observations and historical information, it is found that there are generally three end moraines in front of glaciers in the Gongga mountains. These moraines were formed during the Little Ice Age and represent three glacier advances. During the last 100 years, the glaciers have been in continuous retreat except for two periods of stability or even slight advance, one in the beginning of the 20th century, up to the 1920s, and the other from the middle 1960s to the early 1980s. The amplitudes of glacier fluctuations were greater on the east slope than on the west.

High-latitude atmospheric warming is impacting freshwater cycling, requiring techniques for monitoring the hydrology of sparsely-gauged regions. The submarine runoff of tidewater glaciers presents a particular challenge. We evaluate the utility of Moderate Resolution Imaging Spectroradiometer (MODIS) imagery for monitoring turbid meltwater plume variability in the glacier lagoon Jökulsárlón, Iceland, for a short interval before the onset of the main melt season. Total Suspended Solids concentrations (TSS) of surface waters are related to remotely-sensed reflectance via empirical calibration between in-situ-sampled TSS and reflectance in a MODIS band 1-equivalent wavelength window. This study differs from previous ones in its application to an overturning tidewater glacier plume, rather than one derived from river runoff. The linear calibration improves on previous studies by facilitating a wider range of plume metrics than areal extent, notably pixel-by-pixel TSS values. Increasing values of minimum plume TSS over the study interval credibly represent rising overall turbidity in the lagoon as melting accumulates. Plume extent responds principally to consistently-strong offshore winds. Further work is required to determine the temporal persistence of the calibration, but remote plume observation holds promise for monitoring hydrological outputs from ungauged or ungaugeable systems.

We measured the N2/O2 ratios in clathrate hydrate crystals from Vostok Antarctic ice cores using Raman spectroscopy in order to investigate the spatial distribution of air molecules within a crystal. The results showed that the pattern of the spatial distribution of air molecules in clathrate hydrate depends on the crystal. Some clathrate hydrates have inhomogeneous distributions of the N2/O2 ratio within the crystals, while others are practically homogeneous. The spatial distribution of air molecules within an individual clathrate hydrate changes with time due to three processes: (1) the initial selective enclathration caused by the difference between the dissociation pressures of pure N2- and O2–clathrate hydrates, (2) the diffusive mass transfer of air molecules from surrounding air bubbles through the ice matrix, and (3) diffusion of air molecules in the clathrate hydrate crystal. The dissociation pressures and the diffusion rates of air molecules in ice and clathrate hydrate strongly depend on temperature. Therefore, it is concluded that the pattern of the spatial distribution of air molecules in clathrate hydrate is mainly determined by the depth at which they formed and the temperature in the ice sheet.

The terminus of Columbia Glacier, Alaska, was observed with a single automatic 35 mm camera to determine velocity with a time resolution in the order of a day. The photographic coordinates of the image of a target were then transformed linearly into the direction numbers of the line of sight from the camera to the target. The camera orientation was determined from the film-plane locations of known landmark points by using an adaption of vertical photogrammetry techniques. The line of sight, when intersected with some mathematically-defined glacier surface, defines the true space coordinates of a target, The time sequence of a target’s position was smoothed, first in horizontal x, y space to a straight line, then in y (the principal direction of ice flow) and time with a smoothing cubic spline, and then the x-component was computed from the y-component by considering the inclination of the straight line. This allows daily velocities (about 8 m/day) to be measured at a distance of 5 km, using a 105 mm lens. Errors in daily displacements were estimated to be 1 m. The terminus configuration was also measured using the same photo set.

The Guliya ice cap, on the crest of the Kunlun Shan, central Asia, is an ideal site for acquiring ice cores for climate-change studies. Detailed analyses of the precipitation index (glacier accumulation) and the temperature proxy (δ18O) recorded in the Guliya ice core since 300 years BP show that precipitation correlates with temperature in this region. Climate conditions in the Guliya region since 300 years BP can be separated into three periods: warm and wet from AD 1690 to the end of the 18th century; cold and dry from the 19th century to the 1930s; and warm and wet again since the 1940s. During this period, the climate exhibits just two phases: warm/wet and cold/dry. Comparison of the temperatures and the precipitation recorded in the Guliya ice core shows that variations of temperature and precipitation in the region correlate quite well. However, changes in the precipitation regime appear to lag behind those of the temperature by 20–40 years. We believe this results from the larger heat capacity of the ocean relative to that of the land. Hence, ocean temperatures and corresponding evaporation rates change more slowly than do continental conditions. Additionally, however, positive feedback processes, such as increasing temperatures and precipitation improving vegetation, moisture retention and, hence, local convective precipitation probably play an important role. In this paper, we explain how the timescale of evolving vegetation and the feedback mechanism between precipitation and the temperature could help explain why the changes in precipitation lag those of temperature by 20–40 years over long periods. Taking this time lag into account, we should be able to predict future precipitation trends, based on observed temperature trends.