A review of Holocene climatic variations in different parts of China shows that they were asynchronous. Proxy data from ice cores, pollen, loess, lacustrine sediments, and changes of sea and lake levels demonstrate that many warm and cold oscillations have occurred in China during the Holocene, including a most important climatic event known as the “Holocene optimum,” a milder and wetter period, and that the duration and amplitude of the optimum period, as well as its start and end times, differed in different parts of China. Uplift of the Tibetan plateau over the past millions of years led to the development of the monsoon climate and to complex atmospheric circulation over continental China during the Holocene. As a result, the Holocene optimum began and terminated earlier in high-altitude regions of western China than at lower elevations in eastern China, and the amplitude of the variations was lower in the east. This suggests that the western higher-altitude areas were more sensitive to climatic change than were the eastern lower-altitude areas. Holocene climatic records in the Dunde and Guliya ice cores do not correspond. Inverse δ18O variations between the two cores indicate that the effects of climate and atmospheric processes on the stable isotopes at the two sites differed. The correlation between the isotopic composition of carbonates in lake deposits in western China and climatic variations is similar to that in the ice cores. The climatic resolution in ice cores and lake sediments is higher than that in other media. The lack of precise correspondence of climatic records constructed on the basis of proxy data from different parts of China is a result of the different locations and elevations of the sampling sites, the different resolutions of the source material, and the varied climatic conditions within China. Further work is needed to confirm both the conclusions and the inferences presented here.

Temporal and spatial variations of the seasonal snow cover at 40 sites in Nordland county, Norway, since the last decade of the 19th century are examined. Nordland lies across the Arctic Circle. Annual maximum snow depths there have varied, reflecting the interaction of synoptic conditions, temperature and terrain. North/south and coastal/inland differences are evident, but common temporal trends are identified. Maximum snow depths are strongly related to the winter North Atlantic Oscillation index. Early in the 20th century, the index was positive and the associated stormy conditions resulted in a deep, prolonged snow cover. As the index declined in the 1920s, snow depths decreased sharply. Through much of the second half of the 20th century they increased as the index tended to become more positive. The start and duration of the period of continuous snow cover is influenced by the autumn NAO index. A decrease of duration around 1990 was particularly evident at low-lying stations and those in northern Nordland. The NAO has varied considerably over the past 120 years. Because of its influence, forecasting future trends of snow depth and snow-cover duration is not a simple task.

The glaciers on Yulong mountain (5596 m a.s.l.), China, are the southernmost in mainland Eurasia. The largest is Baishui glacier No. 1. Up to 90% of the annual precipitation there falls in summer, when warm moisture-rich air masses associated with the southwest monsoon reach the area from the Indian Ocean. The winter climate is influenced by air masses with a continental origin and by the southern branch of the westerlies. The snow that accumulates on Baishui glacier No. 1 includes marine aerosols associated with the summer monsoon, and dust brought in winter from central/west Asia, Africa or the Thar Desert area. Studies in May 2006 at two sites, one in the accumulation area (4900 m) and one in the ablation area (4750 m), revealed differences between the ionic composition of the snow that had accumulated in the 2005/06 winter and that of the snow which had been deposited during the preceding summer monsoon. Differences in the chemistry of the summer-accumulated snow at the two sites probably reflected local differences in ablation and elution rates, rather than differences in ion supplies. Differences in the chemistry of the winter-accumulated snow may reflect the influence of up-valley winds, which bring more crustal material to the lower site.

In the summer of 2004, a firn profile, 18.3 m long, extending down to glacier ice, was recovered in the accumulation area of the largest glacier, Baishui No. 1, on Yulong mountain, the southernmost glacier-covered area in mainland Eurasia. Multivariate empirical orthogonal function (EOF) and statistical correlation analyses of major-ion data from the profile demonstrate that three distinct types of ionic material contribute to the chemical characteristics of firn in this monsoonal region: material of marine origin, which is transported by the Indian southwest monsoon; crustal materials, which come from local sources; and anthropogenic pollutants, which are produced by industrial and agricultural activities in South Asia. Although the influence of post-depositional processes on the seasonal isotopic and soluble ionic compositions is significant, dust layers in the firn profile are clearly visible. Due to the effects of meltwater percolation, the dust layers generally coincide with late-summer snow surfaces. We therefore use the dust layers, combined with the seasonal variations of electrical conductivity (EC), Ca2+ and Mg2+, to establish a depth/age scale for the firn profile. The reconstructed net accumulation has a significant negative correlation with the temperature at Lijiang, whereas the correlation between the net accumulation and the precipitation amount at Lijiang is weak. Although the δ18O time series of the firn profile was modified significantly by meltwater percolation, the correlation between annual mean δ18O values and the Indian southwest monsoon index (WSI1) is significant. This result suggests that δ18O records from monsoon-influenced temperate glaciers can provide a valuable record of past variations of the Indian southwest monsoon.

There is no discernible river discharge from Austre Okstindbreen, Norway, in winter; any water formed by basal melting is likely to be stored in isolated cavities or sediments at the bed. In summer, a baseflow component of discharge, relatively depleted of 18O, is diluted by water more enriched in 18O. Glacier ice meltwater with a high δ18O value passes rapidly through channelized systems, and emerges in the glacier river within a few hours. Headward extension of the systems in late summer may tap water stored within the glacier since the previous summer’s close-down. Stored water also is released during early melt-season events, when the low-capacity drainage systems cannot accommodate inputs. The high δ18O value indicates that the probable source of the released water is glacier ice or low-altitude snowfall. Stratigraphic variations of δ18O values, resulting from changing weather conditions, characterize the accumulating winter snowpack. During the melt season, the mean δ18O value of the residual pack rises. The water leaving it, depleted of 18O, passes slowly through the glacier, smoothing out variations of supply. δ18O values of rain vary between and within events, and their effect on glacier-river δ18O values is unpredictable.

Sampling was carried out at Baishui glacier No. 1, the largest glacier on Yulong mountain, China, during the summers of 1999 and 2000, to investigate the spatial variations of oxygen isotopes in the atmosphere–glacier–river system. the results confirm that there is an apparent inverse relation between the oxygen isotopic composition of precipitation and air-temperature/precipitation amount in this region, with lower δ18O values when the amount of precipitation and air temperature in summer is higher, due to the influence of intense monsoon climate on the study area. There are marked differences in the δ18O values of winter-accumulated snow, glacial meltwater, summer precipitation and the glacier-fed river water. Spatial and temporal variations of isotopic composition are controlled by varied weather conditions at different altitudes. Isotopic depletion or fractionation occurs during phase changes, snow-to-ice and ice-to-meltwater transformations and runoff processes.Variations of stable isotopes in glacier runoff can indicate variations of sources of supply. Ionic changes occur as a result of meltwater contact with glacier bed materials.

Stratigraphic variations of oxygen isotopes in the snow which accumulates during the winter at the Norwegian glacier Austre Okstindbreen are not entirely eliminated after 1–2 months of ablation in the following summer. The relationship between regional temperature changes and δ18O values in the snowpack is affected by many natural factors, but 1989/90 winter air temperatures were reflected in the snow which remained on Austre Okstindbreen at 1350 m a.s.l. in July 1990. There were many variations of δ18O values in the 4.1m of snow above the 1989 summer surface, but variations in the underlying firn were relatively small. Meltwater percolation modifies the initial variations of δ18O values in the snowpack. At a site below the mean equilibrium-line altitude on Austre Okstindbreen, increased isotopic homogenization within a 10 day period in July accompanied an increase of the mean δ18O value. Although the isotopic record at a temperate glacier is likely to be influenced by more factors than is that at polar glaciers, it can provide an estimate of the approximate trend of local temperature variations.

Ionic analyses of snow samples collected from snow pits and cores, and samples of meltwater collected from the only river draining the Norwegian glacier Austre Okstindbreen during the 1995 summer, showed that the input/output relations of sodium and chloride were nearly identical. Sampling at the pits revealed that some 72% of the Na+ and Cl– ions which accumulated in winter drained from the snowpack in early June with the first 12% of the meltwater. Concentrations and loads of the two ions in the first meltwater draining from the glacier in late May were relatively high. There then followed a slight decrease in both the concentrations and the loads of the two ions in samples of the river water, and more-or-less steady levels were present for a long period. In late July, concentrations decreased. Loads decreased in early August, indicating that most of the winter-accumulated ions had drained from the catchment. Input and output calculations for Na+ and C1– indicate a total drainage time for the first meltwater from the uppermost part of the accumulation area of 6–7 weeks, equivalent to an average drainage velocity of 100 md–1.

Recent developments of global positioning systems (GPS) have provided opportunities for rapid and frequent glacier mapping. The speed and accuracy of GPS techniques make them particularly suitable for repeated glacier mapping. Using two receivers in differential mode provides very high accuracy. In July 1995, a kinematic differential GPS survey of Austre Okstindbreen, one of the glaciers in the Norwegian national programme of mass-balance studies, provided three-dimensional positions of 2228 points in less than 6.5 h. Handling the data in a geographic information system permitted construction of a triangular irregular network digital terrain model (TIN DTM), which could be compared with TIN DTMs constructed from 1981 and 1993 surveys based on aerial photogrammetry and electronic distance measurement, respectively. A TIN DTM has advantages over the more usual grid-based DTM, which incorporates many interpolated values, although interpolation also is necessary if contours are to be derived from a TIN model. The aspect and gradient of triangular facets in the 1995 DTM have been used to produce a map which has considerable potential for detailed energy-balance studies of the glacier’s accumulation area.

Long-term observations of surface velocities and strain rates at the Norwegian glacier Austre Okstindbreen revealed both temporal and spatial variations. During a period of 6 years, the amount of ice passing through a cross-section slightly below the mean equilibrium-line altitude (1250 m) was some 30% less than the amount which accumulated above the equilibrium line. The mean horizontal component of surface velocity at the centre of the cross-section was of the order of 45–50 m a−1, whilst the thinner marginal ice moved less rapidly. At an altitude of about 1230–1200 m, surface velocities generally increased as the ice entered a steep icefall. In the lower part of the icefall, mean surface velocities again were of the order of 50 m a−1. From there, a general decrease down-glacier was evident, and longitudinal compression along the curving centre line of flow was accompanied by lateral extension. The contribution of internal deformation to surface flow at the lower part of the glacier, which was less than 150 m thick, is likely to have been relatively small, and between-year variations of the horizontal component of surface flow which affected a large area probably were a response to changes of basal sliding rates, reflecting variations of mass balance and water availability.

Large errors in the estimation of glacier ablation and accumulation may arise from the uncritical use of planimetric surface areas in volume calculations based on specific point values. Three-dimensional digital terrain models of glacier surfaces show that the actual surface area is likely to be substantially larger than the planimetric area; with high-resolution digital terrain models, approximations of the true surface area may be as much as 20% larger. The errors are sufficient for questions to be raised about some calculations of water storage in glaciers, because incorrect surface-area values may result in ablation being underestimated substantially. Errors may also be introduced into calculations of radiation-energy inputs to a crevassed glacier surface.

Ionic and isotopic analyses of snow samples collected at four sites at the Norwegian glacier Austre Okstindbreen during two field seasons in 1991 showed that, before melting started, the snowpack was vertically inhomogeneous. Patterns of variation with depth of both ions and oxygen isotopes were maintained throughout the pre-melt period. Horizontal variations of ionic concentration were smaller than vertical ones. The stratigraphic pattern of ionic concentrations in the pack at lower altitudes reflected the influence of melting-refreezing processes, as well as original variations in the falling snow. The mean ionic content of the first set of samples collected at the lowest site was much lower than that at the others, indicating that ions had already been removed by meltwater. Much liquid water was present in the snowpack when drainage started, and ions were removed quickly with the first meltwater. During the melting phase, comparative rates of loss of ions resulting from differential movement through the pack were SO42− > Na+ > Cl−. At 1475m, only 13% of the winter accumulation melted between 6 June and 9 July, but at least 88% of the Na+, 89% of the Cl− and about 100% of the SO42− was lost. Initially, there was no altitudinal trend in the mean δ18O values of the snowpack. Warming of the pack was accompanied by a tendency towards isotopic homogenisation. At the three sites at which snow remained in July, considerable 18O enrichment had occurred since the middle of June.

Winter snow cover at Austre Okstindbreen is influenced strongly by patterns of atmospheric circulation, and by air temperatures during precipitation. Differences of circulation over the North Atlantic and Scandinavia during the winters of 1988–89 and 1989–90 were reflected in the ionic and isotopic composition of snow that accumulated at the glacier. Early summer ablation did not remove, or smooth out, all the initial stratigraphic differences. In the first half of the 1988–89 winter, most air masses took a relatively short route between a marine source and Okstindan; late winter snowfalls were from air masses which had taken a longer continental route. The snow that accumulated in the first half of the 1989–90 winter was associated with air masses which had followed longer continental routes, and so brought higher concentrations of impurities from forests, lakes and crustal material. The ablation season began earlier in 1990 than in 1989, and summer winds and rain supplied more impurities to the snowpack surface.

In the 1870s and 1880s, after a long period of cold conditions, most of the glaciers of Svartisen ended near their maximum Neoglacial limit. Subsequent changes, although principally a response to the climatic controls of mass balance, have been influenced by glacier geometry, including area/altitude relations and aspect, and by glacier dynamics. Calving has played a principal role in the decrease of size of two of the larger glaciers, Austerdalsisen and Flatisen, both of which became unstable once the grounded distal sections of their tongues lost contact with their beds. Mass balance variations reflect climatic controls of the length of the accumulation and ablation seasons, as well as changes of summer temperature. The mass balance record of Engabreen, a maritime outlet of the Vestre Svartisen ice cap, monitored since 1970 by the Norwegian Water Resources and Energy Administration, is not representative of the area as a whole: the more continental glaciers of Østre Svartisen are likely to experience negative net balances when that of Engabreen is slightly or moderately positive. However, the pattern of year-to-year changes of net balance is similar, not only for the Svartisen area as a whole, but also for a larger area.

Twelve years of observation at Austre Okstindbreen, Norway, have demonstrated that the drainage systems of glaciers change with time, both between and within seasons. Random events indicative of instability have been recorded, and disruption of the glacier systems has preceded some outbursts from Kalvtjørna, the glacier-dammed lake. The results of dye-tracer tests suggest that, although discrete systems exist within the glacier, these vary between years. They also demonstrate that some of the water entering the glacier is stored temporarily as the capacities of the systems change. The chemical composition of river water emerging from Austre Okstindbreen differs from year to year, and it is found that both systematic patterns of variation and random deviations from them occur. Although waters of different origin mix within drainage systems, not all systematic patterns of isotopie composition are eliminated by this mixture; diurnal variations are superimposed on longer-term trends, which sheds light on drainage conditions. Between-year differences of within-season trends probably reflect changing spatial patterns of drainage. The general level of oxygen-isotope (δ18O) values of bulk glacier river water in a particular summer is much lower than the values of δ18O for old snow and glacier ice, and indicates the relative contribution of the base-flow component, which may be sustained either by accumulation-area sources or by water release from storage.

Observations of the discharge, electrical conductivity, cationic content, and isotopic composition of glacier-river water indicate that drainage of the lake dammed at the margin of the glacier Austre Okstindbreen, Okstindan, Norway, is preceded by disruption of the glacier’s drainage system(s). Annual studies over a period of 12 years have demonstrated that intense storm precipitation, changes of ablation conditions, and the stage of development of drainage systems all may play a role in triggering drainage of the ice-dammed lake. Water temperature may influence the course of the outburst. The lake has drained on at least ten occasions in the last 12 years. Three of the events (1979, 1985, and 1986) occurred early in the summer, whilst melting of the winter’s snow cover was contributing substantially to glacier-river discharge: high basal water pressure and rapid sliding may have facilitated disruption of drainage conditions within the glacier. In 1982, the lake drained during a severe storm, in 1977 and 1984 shortly after a period of heavy rainfall. During the 1977 and 1984 events, water under pressure burst up through the glacier surface. The lake basin remained partly filled throughout one summer (1980): in-flow of water was balanced by out-flow into the glacier.

The isotopic composition of river water discharging from the Norwegian glacier, Austre Okstindbreen, in summer varies on both daily and longer-term scales. Most δ18o values of samples from the principal river are within the range −12.5 to −14.0‰). Because new snow tends to be relatively depleted of 8180, water leaving the glacier early in the summer has low δ18O values. Subsequently, values rise as contributions of old snow, glacier ice, and their melt waters, which are isotopically heavier (median δ18O values generally above −12.0‰) dilute the δ18O depleted base-flow component of discharge, a mixture of waters with different histories of formation, storage, and transit. Accumulation-area melting contributes significantly to river discharge. Towards the end of the summer, as surface melting declines, δ18O values tend to fall. Between-year differences of within-summer trends reflect differences of development of the glacier’s drainage systems. The drainage systems are affected by outbursts from a glacier-dammed lake. During fine weather, δ18o variations follow the diurnal cycle of surface melting: they are strongly correlated with, but lag behind, air temperatures. Perturbations during rainfall cannot be explained simply in terms of the isotopic composition of the precipitation, since low values may be associated with isotopically heavy rainfall. Displacement of water previously stored within or below the glacier may account for the anomaly. Contrasts of composition characterize different rivers leaving the glacier, because the relative contributions of various water sources differ.

Basal ice at the glacier Østerdalsisen commonly deforms under stress within cavities at the glacier bed. Some ice subject to rapid strain, however, fails in a brittle manner. The creep-rate of basal ice is influenced by sediment particles within it, and by ice grain-size and structural anisotropy; a flow law for such ice has not been derived experimentally. Near the glacier bed, particles enclosed in ice may migrate as a result of stress concentration, bubbles may be flattened, and anisotropic structures may develop. Recrystallization leads to grain-size changes. Both regelation spicules and layers of regelation ice, generally thin, form within subglacial cavities but their occurrence is limited. Regelation-ice formation has a significant influence on the distribution of rock debris at the ceilings of subglacial cavities.