Due to their remote location within the Russian High Arctic, little is known about the mass balance of ice caps on Severnaya Zemlya now and in the past. Such information is critical, however, to building a global picture of the cryospheric response to climate change. This paper provides a numerical analysis of the climate and mass balance of the Vavilov Ice Cap on October Revolution Island. Mass balance model results are compared with available glaciological and climatological data. A reference climate was constructed at the location of Vavilov Station, representing average conditions for the periods 1974–1981 and 1985–1988. The site of the station has a mean annual temperature of −16.5°C, and an annual precipitation of 423 mm water equivalent. The mass balance model was calibrated to the measured mass balance, and tested against the time-dependent evolution of the englacial temperatures (to a depth of 15 m). The mass balance model was then converted to a distributed model for the entire Vavilov Ice Cap. Model results predict the spatial distribution of mass balance components over the ice cap. Processes involving refreezing of water are found to be critical to the ice cap's state of health. Superimposed ice makes up 40% of the total net accumulation, with the remaining 60% coming from firn that has been heavily densified by refreezing.

To understand how ice masses in the Russian High Arctic respond to climate change, the processes that influence their current mass balance must be evaluated. A mass balance model was coupled with an ice-flow model to determine the influence of the present climate regime on the dynamics of the Vavilov Ice Cap, October Revolution Island, Severnaya Zemlya. Model results show that the bulk of the ice cap is flowing relatively slowly, at a velocity of around 5 m a⁻¹. However, the climate regime encourages the ice cap to migrate toward the precipitation source in the southwest. The ice cap may not, therefore, be in equilibrium with the present climate. Given that the response time of the ice cap is of the order of 1000 years, this non-equilibrium may be related to changes in climate that occurred during the Little Ice Age, when the ice cap may have been north of its present position.

A coupled surface mass balance and ice-flow model was used to predict the response of three ice caps on Severnaya Zemlya, Russian Arctic, to the present climate and to future climate changes as postulated by the Intergovernmental Panel on Climate Change (IPCC). Ice cap boundary conditions are derived from recent airborne geophysical surveying (Dowdeswell et al., 2002), and model inputs are constructed from available climate data. Model results indicate that, currently, the state of balance of ice caps on Severnaya Zemlya is dependent on their size. For small ice caps, such as Pioneer Ice Cap (area 199 km²), mass balance is extremely negative. Under current climate conditions, these relatively small ice caps are predicted to disappear within ∼1000 years. For larger ice caps, however, such as the Academy of Sciences Ice Cap (area 5586 km²), the accumulation zone is much larger, which results in these ice caps being approximately in balance today, but still susceptible to decay in future climate scenarios. When climate conditions are changed in the model, as predicted by the IPCC, the mass balance of all ice caps in Severnaya Zemlya is predicted to become negative within a 100 years or so. Although it is difficult to say with certainty the exact rate of decay, it is likely that ice loss from Severnaya Zemlya will contribute, over a period of a few hundred years, a rise in sea level of the order of a few centimeters.

Effects of abiotic factors on daily and annual photosynthetic carbon gain were evaluated in Abies lasiocarpa and Picea engelmannii at three sites across an alpine treeline ecotone in the Medicine Bow Mountains of southeastern Wyoming (U.S.A.). In addition, the year 2001–2002 was characterized as an episodic drought (seventh driest year since 1895), including a winter that generated only 45% of normal snowpack. Both species had approximately 50% lower xylem water potentials and photosynthesis compared to previous studies for the same species and locale. In A. lasiocarpa, estimated total photosynthesis for the measurement period (A_tot) was greatest (28.7 mol m⁻²) at the mid-ecotone site (∼3198 m), followed by the alpine site (24.6 mol m⁻²) at ∼3286 m, and then the forest site (19.4 mol m⁻²) below timberline (∼2965 m). Similar results occurred in P. engelmannii (17.6, 23.4, and 25.3 mol m⁻², respectively). These differences appeared to be most influenced by stomatal rather than non-stomatal effects based on comparisons of photosynthesis, leaf conductance, and internal CO₂ concentrations through summer. Although photosynthesis over the summer appeared limited primarily by annual water limitation, the two higher elevation sites had significantly greater values that were associated with microclimatic differences in sunlight incidence and, possibly, temperature.

Active layer thickness was monitored along three ephemeral streams in the Taylor Dry Valley of Antarctica during the 1997–1998 summer season. Five to seven cross sections were established on each stream, and the thickness of the active layer was measured every 1.5 m over intervals ranging from 2 to 30 days. Active layer depths ranged from a minimum of 3 cm in early November to a maximum of 60 cm in late January, and the depth of the active layer increased rapidly as summer temperatures climbed above freezing. While there were significant differences in the thickness of the active layer among the three streams, the timing of rapid thaw was similar for all cross sections. Changes in active layer thickness were responsive to both daily and seasonal changes in air temperature. There was more rapid thaw under the areas with flowing water, suggesting a transfer of heat from meltwater into the underlying sediments, and some evidence of an insulating effect during cold periods. Active layer thickness was not strongly related to modeled differences in incoming solar radiation using 30 m grid cells.

The rock-dwelling pikas of Asia and North America are suitable model species for studying foraging strategies of small generalist herbivores, because they collect and store green parts of plants for winter. In the past, contents of these stores were subjected to numerous studies but researchers differed in opinions on selective versus opportunistic plant-gathering by pikas. We analyzed plant species composition and their shares (%) in caches and in surrounding habitats in six territories of Ochotona hyperborea in Siberian mountains. We applied Ivlev's Electivity Index for assessing selectivity. We found that some plant species were evidently preferred and others avoided by caching pikas. Among the former, many were rich in secondary compounds, while among the latter, evergreen tuft-forming plants prevailed. Our data conform to earlier findings on selective foraging by the American pika Ochotona princeps, and prove great similarity in winter diet of both species. We discuss possible cues used by rock-dwelling pika species to choose which plants to collect, and suggest that their harvesting strategy is most economic in harsh high-mountain habitats.

The hydrologic system of the coastal McMurdo Dry Valleys, Antarctica, is defined by snow accumulation, glacier melt, stream flow, and retention in closed-basin, ice-covered lakes. During the austral summers from 1993–1996 and 1999–2000 to 2002–2003, fresh snow, snow pits, glacier ice, stream water, and lake waters were sampled for the stable isotopes deuterium (D) and ¹⁸O in order to resolve sources of meltwater and the interactions among the various hydrologic reservoirs in the dry valleys. This data set provides a survey of the distribution of natural water isotope abundances within the well-defined dry valley hydrologic system in Taylor Valley, which extends 20 km inland from McMurdo Sound. The three major Taylor Valley lakes are not connected to one another hydrologically, and their levels are maintained by glacial meltwater inflow and perennial ice-cover sublimation. At the valley scale, glacial ice, snow, stream, and lake waters become more depleted in δD with increasing distance from McMurdo Sound (further inland). Snow pack in glacial accumulation zones is heterogeneous, likely a result of varying storm sources (continental versus coastal), and, in general, snow pits, fresh snow samples, and glacier ice are more depleted than stream waters. Within the lake basins, glacial ice source waters are depleted by as much as 111‰ δD and 20‰ δ¹⁸O compared to lake waters. These results demonstrate the importance of in-stream fractionation at the valley scale. In-stream enrichment occurs through direct evaporation fractionation from the channel and hyporheic exchange with isotopically enriched waters in the near-stream subsurface during transport from the glacial source to lake. Furthermore, the results show that lake waters directly reflect their glacial ice sources, despite fractionation during stream transport. Inter-annual comparisons of lake profiles suggest that lake waters are directly influenced by the isotopic composition and amount of stream flow during a season.

The present investigation of High Arctic epilithic lichens and their substrate is based on field observations in Inglefield Land, North-West Greenland, mainly in 1999, with subsidiary observations from 1995. Eighteen rock samples, all glacial erratics, were specifically selected on the basis of macroscopic mineralization features such as iron and copper staining, vein and breccia structures, and ore minerals. The samples are representative of the crystalline shield, and their lithologies can be matched with exposures in Inglefield Land. Seven lichen communities are recognized, viz. Pleopsidium chlorophanum c., Xanthoria elegans var. splendens c., Dimelaena oreina–Physcia caesia–Xanthoria elegans c., Xanthoria elegans–Umbilicaria virginis c., Orphniospora moriopsis c., Porpidia flavicunda c., and Tremolecia atrata c. The studied material on the 18 samples reveals no conspicuous correlation between metal concentrations in the rock samples and the lichen communities and, broadly speaking, it can be stated that the lichens reflect more the properties of the rock surface, such as, for example, nitrogen- and iron-bearing weathering crusts, than the mineralogical composition of the rocks. However, there is a very close affinity between the Orphniospora moriopsis community and one variety of syenitic rocks with elevated magnetite and phosphorus.

Small (1 ≤ m diameter) sorted patterned ground features were studied on the Little Ice Age forelands of three Jotunheimen glaciers. Patterned ground appears to be most active near the ice margins, declining in intensity of activity with distance from the glaciers. Vegetation and soil development are negligible within patterned ground that is “Recent” (decadal time frame). Significant (P < 0.05) fine scale differences in vegetation and soil development occur within patterned ground on terrain ∼70 yr in age, with patterned ground borders having higher values of vegetation cover and thicker soils than that in patterned ground centers. With increasing age of terrain and patterned ground, soil development and vegetation encroach inward toward patterned ground centers, implying that a short-term, active periglacial zone exists near the ice margin, decaying with time and glacier retreat. Specifically, terrain that has been deglaciated for ∼70 years and is approximately ∼350–500 m from the ice margin shows a significant decline in frost activity, allowing for the initiation of pedogenesis and vegetation colonization.

A large, late-melting snowbed and famous landmark was analyzed on a south-facing slope in the Giant (Krkonose/Karkonosze) Mountains, the High Sudetes, Czech Republic. So far, only its maximum snow depth, reportedly between 4 and 20 m, had been merely estimated. Wire probes can be reliably used up to snow depths of 3 m only. To get more realistic data, two digital models using kinematic carrier phase–based GPS measurements were developed: (1) a model for snow surface data, applied at the end of five winter seasons from 2000 to 2004, and (2) a model for the underlying snow free ground surface, applied after the snow melt in August 2000. These two models, overlaid in the GIS environment, have identified snow depths for each of the 111 phytosociological relevés in plots 2 m × 2 m in size. The snow depth maxima recorded in the above given winter seasons were 15.7, 6.1, 13.4, 7.6, and 14.2 m, respectively. To determine the effect of the obtained variables on the vegetation pattern, the relevant snowpack thickness together with snow melting rate, position of the relevé, amount of soil skeleton, depth of litter horizon, and depth of the soil profile were used as environmental variables in the Canonical Correspondence Analysis (CCA), which explained 23.1% of the species data variability. The most powerful environmental variables were soil parameters. The vegetation cover significantly decreased as a function of the snow depth. The tiny forb Gnaphalium supinum and the grasses Avenella flexuosa, Deschampsia cespitosa, and Nardus stricta appeared to be the most tolerant species surviving under the deep snow layer and possessing a short vegetation season. Comparison with an earlier study suggested a stabilized pattern of the snow-patch vegetation even after about 50 years.

Low temperatures and the short growing season in high altitude snow patches in temperate mountains constrain life cycles and reproduction of snowbed species. This leads to a highly adapted timing of sexual reproduction. Winter precipitation and temperature, the main factors determining growing season length, are predicted to change with global warming. To understand their impacts on plant phenology, we studied the responses of seven alpine vascular plant species during 2001.

Temperature had a clear impact on phenological patterns. The start of the reproductive development was not directly linked with the date of snowmelt, but rather with the cumulative energy input. In addition, photoperiodism may also contribute to the control of plant development through an increasing temporal adjustment of phenology until flowering.

Pårteglaciären in northern Sweden has a response time of ∼200 years, demonstrating a long response time for a continentally located glacier. Pårteglaciären is a polythermal valley glacier presently covering an area of 10 km². Its size will be reduced another 60–70% if the present climate persists and will then only have ∼30% of its Little Ice Age maximum volume left. Future global warming will of course enhance melt rates, and the relative size and volume reduction will probably be even larger. Photogrammetric studies between 1963 and 1992 show a general thinning of the entire glacier except for the center one of the three cirques in the accumulation area, which seems to have a surface elevation in balance with present climate. Balanced flow studies performed using GPS and Ground Penetrating Radar at the outlet of the cirques gave negative values for two cirques and a positive value for the center cirque. The future Pårteglaciären will split up into three small glaciers, and only the center one will extend beyond its cirque.

Trees have a common high elevation distribution limit at similar soil temperatures across the globe. Here we tested whether low temperature in the root zone alone can induce the well known dwarfing at the low temperature growth limit of trees by using a “natural experiment” with trees growing on low elevation permafrost ground. At the natural high elevation treeline, both air (shoot) and soil (root) temperature are low, while at the montane permafrost site in the Swiss Jura mountains, roots are cold, but not shoots. Soil temperature records confirmed that the low elevation study site resembles thermal conditions typical for the high elevation treeline. The warm air conditions have no ameliorating effect on tree growth. Irrespective of shoot temperatures, the root zone temperature and the associated metabolism appear to determine tree growth at this site. The test revealed a critical role of soil temperature, which by itself is sufficient to explain a growth limit of trees associated with a seasonal mean soil temperature at 10 cm depth of around 6°C.

Surface horizons of many alpine soils on Quaternary deposits in high-mountain settings are enriched in silt. The origin of these particles has been debated, particularly in the Rocky Mountain region of North America. The most common explanations are frost shattering of coarser particles and eolian additions from distant sources. We studied soil A horizons on alpine moraines of late-glacial (Satanta Peak) age in the Colorado Front Range. Surface horizons of soils on these moraines are enriched in silt and have a particle size distribution that resembles loess and dust deposits found elsewhere. The compositions of sand and silt fractions of the soils were compared to possible local source rocks, using immobile trace elements Ti, Nb, Zr, Ce, and Y. The sand fractions of soils have a wide range of trace element ratios, similar to the range of values in the local biotite gneiss bedrock. In contrast, silt fractions have narrower ranges of trace element ratios that do not overlap the range of these ratios in biotite gneiss. The particle size and geochemical results support an interpretation that silts in these soils are derived from airborne dust. Eolian silts were most likely derived from distant sources, such as the semiarid North Park and Middle Park basins to the west. We hypothesize that much of the eolian influx to soils of the Front Range occurred during an early to mid-Holocene warm period, when sediment availability in semiarid source basins was at a maximum.

Higher plant species richness has been proposed to increase the resilience of plant communities to disturbance. The purpose of this study was to test whether this is true for reindeer grazed arctic tundra vegetation. Plant biomass, plant community structure, and species richness were measured along four fences that separated areas grazed by reindeer from ungrazed areas in northern Norway. I found a negative relationship between plant species richness and the change in species richness and biomass due to grazing. These results indicate diversity did not confer greater resilience to increased reindeer grazing intensity. No support for higher grazing pressure in diverse habitats were recorded, thus, these results suggest lower resilience to grazing in species-rich arctic tundra vegetation.

Turbulent sensible and latent heat exchanges play an important role in melting snow covers, contributing 30–40% of overall melt energy with daily values reaching over 50% on warm, cloudy days (Morris, 1989). The spatial variability of these turbulent fluxes across a basin and the relative importance of the differences is not well known. This paper specifically addresses small-scale variabilities in sensible and latent energy fluxes related to topographically induced wind speed variations. A simple wind model was used to simulate topographic effects on the surface wind field. Hourly wind observations were areally distributed by the model and used to calculate spatially variable sensible and latent turbulent heat fluxes for a small (63 km²) research catchment dominated by open tundra vegetation. Simulations showed that, even though the study area is characterized by relatively low relief (average slope 3°), the small-scale sensible and latent heat fluxes varied considerably throughout the basin. The resulting variations in snowmelt rates play an important role in the development of a patchy snow cover. Overall, turbulent fluxes within the research area varied by as much as 20% from the mean, leading to differences in potential snowmelt of up to 70 mm snow water equivalent over the entire melt period.

Long-term records from meteorological stations on the Antarctic Peninsula show strong rising trends in the annual duration of melting conditions. In each case, the trend is statistically significant and represents a major increase in the potential for melting; for example, between 1950 and 2000 the record from Faraday/Vernadsky Station showed a 74% increase in the number of positive degree-days (PDDs). A simple parameterization of the likely effects of the warming on the rate of snow melt suggests an increase across the Antarctic Peninsula ice sheet from 28 ± 12 Gt a⁻¹ in 1950, to 54 ± 26 Gt a⁻¹ by 2000. Given a similar rate of warming over the next 50 years this may reach 100 ± 46 Gt a⁻¹. The majority of this increased meltwater does not drain into the sea but is refrozen in the ice sheet, and it is difficult to predict the fraction of ablation that will become runoff; however, a calculation based on an established criterion for runoff indicates that the contribution from the Antarctic Peninsula, as a direct and immediate response to climate warming is significant, equivalent to (0.008–0.055) mm a⁻¹ of global sea level rise. Given future warming this could easily treble in the coming 50 years. This contribution due to increased runoff could be augmented by any dynamic imbalance in the glaciers draining the ice sheet. This finding appears to contradict the conclusions of previous assessments, including the Intergovernmental Panel on Climate Change, which considered the contribution of runoff from Antarctica to sea level rise would be insignificant.