Tasman Glacier is the largest glacier in the New Zealand Southern Alps. Despite a century of warming and down-wastage, the glacier remained at its Little Ice Age terminus until the late 20th century. Since then, a proglacial lake formed, and comparatively rapid calving retreat has been initiated. In this paper we use sequential satellite imagery to document terminus retreat, growth of supraglacial ponds, and expansion of the proglacial Tasman Lake. Between 2000 and 2008, the glacier terminus receded a maximum of c. 3.7 km on the western margin, and the ice-contact Tasman Lake expanded concomitantly. This northward expansion of Tasman Lake up-valley proceeded at a mean annual rate of 0.34 × 10⁶ m² a⁻¹ over 2000–2008, attaining a surface area of 5.96 × 10⁶ m² in May 2008, with a maximum depth of c. 240 m. Terminus retreat rates (U_r) vary in both space and time, with two distinct periods of calving retreat identified during the study period: 2000–2006 (mean U_r  =  54 m a⁻¹) and 2007–2008 (mean U_r  =  144 m a⁻¹). Terminus retreat can also be categorized into two distinct zones of activity: (1) the main ice cliff (MIC), and (2) the eastern embayment ice cliff (EEIC). During the period 2000–2006, and between 2006 and 2008 for the EEIC, the controlling process of ice loss at the terminus was iceberg calving resulting from thermal undercutting. In contrast, the retreat of the MIC between 2006 and 2008 was controlled by buoyancy-driven iceberg calving caused by decreasing overburden pressure as a result of supraglacial pond growth, increased water depth, and rainfall. The presence of a >130-m-long subaqueous ice ramp projecting from the terminal ice cliff into the lake suggests complex interactions between the glacier and ice-contact lake during the 8–10 km of possible future calving retreat.

In this first systematic classification of the snowpack in central Svalbard a new additional snow climate is presented. Based on field observations in the 2007–2009 period, 109 snow pits were quantitatively analyzed in terms of temperature gradients, grain shapes, grain sizes, and hardness of every snow layer. Emphasis was given to the occurrence of depth hoar, ice layers, the most observed weak layer–bed surface interfaces. These parameters in combination with meteorological observations define the “High Arctic maritime snow climate” as having a very thin and cold snowpack, a basal layer of depth hoar with winds labs and ice layers on top. The snowpack lasts for 8–10 months of the year, at higher grounds for the whole year. Snow climate classifications are an important part of improving the local avalanche characterization. This is timely, especially for the area around Svalbard's main settlement Longyearbyen, where avalanches represent a natural hazard. Also, climate models for the area predict changing meteorological conditions, especially more solid precipitation, thus a description of the snow climate as it is today is important. This “High Arctic maritime snow climate” characterization is based on the 16.8 km² mountainous area around Longyearbyen at 78°N, and does not fit any other High Arctic location. Svalbard has in comparison to other High Arctic locations milder climate due to an overall meteorological maritime influence.

Antarctic ice-free areas contain lakes and ponds that have interesting limnological features and are of wide global significance as early warning indicators of climatic and environmental change. However, most limnological and paleolimnological studies in continental Antarctica are limited to certain regions. There are several ice-free areas in Victoria Land that have not yet been studied well. There is therefore a need to extend limnological studies in space and time to understand how different geological and climatic features affect the composition and biological activity of freshwater communities. With the aim of contributing to a better limnological characterization of Victoria Land, this paper reports data on sedimentary pigments (used to identify the main algal taxa) obtained through a methodology that is more sensitive and selective than that of previous studies. Analyses were extended to 48 water bodies in ice-free areas with differing lithology, latitude, and altitude, and with different morphometry and physical, chemical, and biological characteristics in order to identify environmental factors affecting the distribution and composition of freshwater autotrophic communities. A wider knowledge of lakes in a limnologically important region of Antarctica was obtained. Cyanophyta was found to be the most important algal group, followed by Chlorophyta and Bacillariophyta, whereas latitude and altitude are the main factors affecting pigment distribution.

The retreat of glaciers during past decades has led to the emergence of large rock outcrops in many glaciated areas around the world. Primary succession of vegetation in glacier forelands has been described for many regions, but most studies have been conducted on glacial deposits, whereas deglaciated rock outcrops have received little attention. This study assesses the pattern of primary succession on a chronosequence of five rock outcrops exposed during the past 140 years by the retreat of Glaciar Frías in the Patagonian Andes, Argentina. Data on floristic composition and species cover for algae, lichens, ferns, bryophytes, and vascular plants were recorded on sampling plots. Ordination and classification analyses discriminate three major successional stages, each dominated by a different species assemblage, suggesting directional replacement of species in the succession. The pioneer stage is dominated by the crustose lichen Placopsis perrugosa, the mid-successional stage by a lichen-moss mat dominated by the moss Racomitrium lanuginosum, and the late-successional stage by a large diversity of vascular plants. The low density of Nothofagus dombeyi saplings in the late-successional site indicates that plant succession is still in progress 140 years after deglaciation. Progress in succession appears to be influenced by species life-cycle traits and facilitative interactions among species. The comparison of the successional processes between rock outcrops and unconsolidated glacial deposits suggests that the vegetation sequence is similar, but the rate of succession is slower on rock outcrops. The development of a ground lichen-moss cover, previous to the widespread colonization by vascular plants, accounts for the slower succession progress on rock outcrops. The establishment of Nothofagus stands takes at least 100 yrs longer on the rock outcrops than on glacial deposits. Under predicted climate warming, most Patagonian Andes glaciers will continue the retreat along steep bedrock slopes, where similar, long-term vegetation successional patterns to those observed on Glaciar Frías foreland will eventually occur.

The marked change in above-ground forest stand structure with elevation towards the alpine treeline has been widely recognized, while studies on altitudinal effects on the root system are still scarce. We studied Norway spruce stands along a 700-m-long elevational transect at Mount Brocken (Harz Mountains, central Germany) to test the hypothesis that fine root dry mass partitioning shows an inverse response to elevation towards the treeline compared to above-ground biomass. Microclimate measurements revealed that thermal conditions at the treeline of Mount Brocken are closely comparable to other treeline sites around the world. Above-ground structure did not differ significantly among stands at lower and mid elevations, but tree height and stem biomass decreased strongly with elevation upslope. Fine root biomass increased with elevation by a factor of nearly two. Annual fine root production was found to be highest at mid elevation but was only 40% lower than this maximum at the treeline. Consequently, the ratio of fine root production to above-ground stem biomass increased by a factor of 2–3 with elevation, indicating a strong shift of below- versus above-ground carbon allocation towards the treeline. We hypothesize that the enlargement of the fine root system at cold sites represents an adaptation to the unfavorable soil conditions, such as impaired nutrient supply.

Tree-ring width and glacier mass balance are two highly sensitive climatic proxies which are often used as indicators of biological and geophysical changes in high-altitude ecosystems. Tree-ring data have been widely used to reconstruct past temperatures and also to reconstruct past glacier mass balance. Here we show that tree-ring chronologies from a high-altitude Pinus cembra L. dendroclimatic network and glaciers from the same region in the European Alps have non-stationary responses to air temperature, and have also been responding non-proportionally to temperature extremes in recent decades. Both ring-width chronologies and the mass-balance series of some glaciers from the same region have shown an increasing sensitivity to summer (JJA) temperatures. Our results demonstrate that the sensitivity to climate of tree-ring chronologies and glacier mass balance may change over time and has been increasing in recent decades, posing some limitations to tree-ring-based glacier mass-balance reconstruction. Moreover, we found these reconstructions in the European Alps are more reliable for large rather than for small glaciers, and may not be able to reveal years of extreme ablation that could have occurred in the past.

In this study, we used a 4.00-m pit on Belukha glacier in Russia's Altai region and attempted to establish the timing of chemical deposition events by analyzing pollen profiles. As the pollen deposition of each examined taxon on the glacier surfaces followed a distinct seasonal phenology, seasonal layers could be identified over a two-year period. The seasonal layer boundaries reconstructed from the pollen analyses were in close agreement with the in situ observations and indicated that the snow deposition on the glacier originates mainly from summer precipitation. The record of oxygen isotope ratios showed a relatively high mean value of −13.3‰, which was attributed to the absence of winter depositions. The formate (HCOO⁻) concentration records displayed seasonal variation with the highest emissions occurring in the spring, and a dust event in the spring of 2003 was detected from the Mg² , Ca² , and dust concentration profiles. Taken together, these results suggest the analysis of pollen profiles in combination with chemical data in snow pits and ice cores may lead to better reconstruction of seasonal variation.

Truelove Lowland on Devon Island, Nunavut (75°N), has long been investigated for its flora, fauna, and microbiota. Unlike ectomycorrhizae, endomycorrhizal interactions have been described as sparse or absent in this High Arctic environment. To probe this observation, samples of roots and associated soils (55 plants in total) from 10 genera in 9 families were collected during July 2006. Fungi growing within these roots were visualized using our high-sensitivity lactofuchsin epifluorescence method. Fungal colonization within plant roots (collectively, endorhizal fungi) was assessed with our quantitative microintersect method. Of the 3988 intersections assessed at 400× total magnification, only 154 lacked fungi. Most colonization was by septate endophytes (average abundance 66%, range 13–100%), and fine endophytes (average abundance 48%, range 0–100%). Endorhizal morphology in Dryas and Saxifraga roots typically consisted of thin extraradical hyphae that formed a sheath and grew between and within root cortical cells, resembling ericoid or ectendomycorrhizae. Soil in which the Truelove plants had grown, which had been stored at −20 °C, was planted with wheat seeds. After 10 weeks, fungal colonization of these roots was 35–100%. Endorhizal fungi are typically present in roots of plants living on Devon Island tundra.

Understanding relationships between snow accumulation and synoptic climatology is important for assessing the way in which future climate variability will impact on glacier mass balance. However, few studies have as yet examined these relationships. Variability in snow accumulation on mid-latitude glaciers is strongly influenced by atmospheric circulation, orography, and redistribution of snow by wind. Very little is known about these processes in the New Zealand Southern Alps, where it is assumed that west-facing glaciers receive higher snow totals. However, few measurements are available to test this hypothesis. These processes were investigated over a 21-day period in winter 2008 on glaciers located west (Franz Josef Glacier) and east (Tasman Glacier) of the Main Divide of the Southern Alps. We directly measured snow accumulation and considered how it was affected by synoptic weather regime and location with respect to the Main Divide. Both glaciers received ∼75% of their snowfall during troughing regimes, which are characterized by strong westerly quadrant winds bringing humid air masses from the Tasman Sea over the Southern Alps. The Franz Josef Glacier site received ∼30% more snow than the Tasman Glacier site, but wind deflation meant that by the end of the study period, net snow accumulation was similar at both sites. Blocking synoptic regimes resulted in a reversal of prevailing westerly flow, generating strong downslope winds at Franz Josef Glacier and snow loss.

Winter snowfall is increasing in many Arctic regions and climate models predict this trend will persist in the coming century. We examined the effects of two levels of increased winter snow accumulation on soil microclimate, plant and soil nutrient status, plant phenology and ecosystem CO₂ exchange after five years of treatment in a widespread High Arctic ecosystem. Increased snow cover resulted in greater winter CO₂ efflux, altered growing season soil nutrient availability and greater leaf nitrogen concentrations during the snow-free season. Modest increases in snow cover ( 0.25 m above ambient) increased gross ecosystem photosynthesis (GEP) without increasing ecosystem respiration (ER), while the deepest snow cover ( 0.75 m above ambient) increased both GEP and ER. The area of intermediate snow addition was a smaller source of CO₂ to the atmosphere during the growing season when compared to the ambient and deep snow areas. The intermediate and deep snow areas apparently had similar effects on the functioning of the vegetation community (increased GEP), but divergent effects on the soil microbial respiration, as evidenced by the changes in ER. This nonlinear response to increasing snow depth demonstrates the potential for complex High Arctic ecosystem responses to changes in winter precipitation.

Whitebark pine (Pinus albicaulis) is a foundation and keystone species of upper subalpine and treeline ecosystems throughout the western United States and Canada. During the past several decades, Cronartium ribicola, an introduced fungal pathogen that causes white pine blister rust in five-needled pines, has caused significant declines in whitebark pine throughout its range. Our research objectives were to examine geographic variation in blister rust infection (total canker density) in whitebark pine found at six alpine treelines east of the Continental Divide in Glacier National Park, Montana, and to determine which environmental factors have the greatest influence on blister rust infection at treeline. Within a total of 30 sampling quadrats (five at each treeline study site), we measured the number of cankers on each whitebark pine in order to assess how blister rust infection varied throughout our study area. We created high-resolution digital elevation models to characterize surface microtopography, and used a geographic information system (GIS) to derive environmental variables of interest. A mixed effects, Poisson regression model determined environmental correlates of blister rust from the resulting set of field and GIS-derived variables. We found that rates of infection varied considerably among treelines, and that treeline sites exhibiting high flow accumulation rates, greater distances to wetlands, slopes facing southwest, higher curvature, greater wind speeds, and close proximity to Ribes and perennial streams had the highest rates of blister rust infection.

For numerous climate studies, snowpack density is used to determine snow water equivalent from snow depth (or the reverse) or to determine snow surface albedo through the characterization of aging snow covers. In addition, high spring snowpack water content (and thus density) can act as a catalyst for wet avalanches. Surprisingly, there are few empirical studies that focus on spring snowpack density. In this study, spring snowpack densities in the western United States are statistically related to four variables that characterize the antecedent winter conditions: (1) mean air temperature for days without snowfall, (2) the fraction of precipitation falling as snow, (3) total precipitation, and (4) mean snowfall density. Areal composite regression analysis for the western United States indicates a highly significant (p  =  0.005) positive relationship between winter precipitation total and April 1 snowpack density. This relationship weakens in lower elevation regions and coastal regions where warmer winter temperatures are conducive to more frequent rain events and melt events which affect snowpack density and ablate snow cover. These empirical results are supported by a simple snowpack model. The significant positive relationship between precipitation and density is likely due to increased densification rates through gravitational compaction from the presence of greater snow water equivalent resulting from more snowfall.

Trends of Normalized Difference Vegetation Index (NDVI) from 1982 to 2006 in the upper mountainous areas of three inland river basins (Shiyanghe, Heihe, and Shulehe, from east to west) in the Qilian Mountains, northwestern China, were analyzed based on the Global Inventory Monitoring and Modeling Studies (GIMMS) NDVI data. The relationships between NDVI and climatic factors such as air temperature, precipitation, and evaporation were also analyzed. The results indicate that changes of NDVI over time had an obvious elevational difference. NDVI has decreased in the northern lower-elevation (<3000 m) areas, which account for 31% of the total area, and increased in the southern higher-elevation (3000–4100 m) areas, which occupy 32% of the total area. In addition, 37% of the area did not show an obvious change in NDVI and was distributed in the periglacial belts with elevations higher than 4100 m. The decrease of NDVI in the lower elevations was controlled by a decrease in precipitation and an increase in air temperatures, whereas the increase in the higher elevations was mainly controlled by an increase in air temperature alone. With a continuous increase in air temperature in the future, vegetation would suffer from more serious water stress in the elevations lower than 3000 m, but become more flourishing between 3000 and 4100 m in the Qilian Mountains. This information is critical for understanding how climate warming may affect hydrology and ecology in the Qilian Mountains and for managing water resources for the lowlands in the Hexi Corridor adjacent to the mountains.

Ecosystem respiration is important because it is the small imbalances between CO₂ uptake via photosynthesis and CO₂ release by ecosystem respiration that determine the effect of the biosphere on atmospheric CO₂. For subalpine grasslands with mild winters we do not know the size of under-snow respiration relative to the total annual ecosystem respiration. This study determines the contribution of respiration through snow to total annual respiration, and models annual ecosystem respiration based on relationships with soil temperature and water content. Measurements were made monthly for two years in an unmanaged subalpine grassland in the Snowy Mountains of Australia. The vegetation is sparse (aboveground mass  =  355–605 g m⁻², belowground mass  =  570–1010 g m⁻²) and dominated by native perennial C3 grasses and sedges. Ecosystem respiration was positively related to temperature, and there was some evidence that ecosystem respiration was more temperature sensitive at temperatures between 0 and 2 °C than at warmer temperatures. Annual ecosystem respiration was 12.1 Mg C ha⁻¹ yr⁻¹ in 2007/2008 and 10.5 Mg C ha⁻¹ yr⁻¹ in 2008/2009. Maximum daily rates of ecosystem respiration of 7 µmol CO₂ m⁻² s⁻¹ occurred during summer, while minimum rates occurred under snow cover and were 0.2 to 0.9 µmol CO₂ m⁻² s⁻¹. The duration of permanent snow cover was 60–68 days (equivalent to 16–18% of the year) and ecosystem respiration under snow was 4.1 to 4.3% of annual ecosystem respiration, which is smaller than the 10–50% commonly reported from studies in areas with longer snow-covered periods.

Weather and climatic conditions over the Himalaya regions are of great interest to the scientific community at large. The objective of this study is to present spatial and temporal variations of air temperatures and relative humidity on the north slope of Mt. Qomolangma. Both hourly air temperatures and relative humidity were measured at seven automatic weather stations (AWS) from 5207 to 7028 m a.s.l. from May 2007 through September 2008. Long-term (1959–2007) air temperature and precipitation data were obtained from Dingri Meteorological Station. The preliminary results show that the elevational gradient of mean annual air temperature is non-linear, which decreases from 0.2 °C at an elevation of 5207 m to −4.4 °C at 5792 m, and −5.4 °C at 5955 m. The maxima are 14.6, 9.1, and 18.6 °C, and the minima are −24.2, −28.8, and −29.3 °C at the three elevations, respectively. The relative humidity does not change significantly with increasing elevation except over glacier ice, but the mixing ratio decreases due to the decrease in air temperature. The mean diurnal ranges of air temperature and relative humidity decrease with increasing elevation. The daily maximum air temperature occurs significantly later at the high-elevation site than that at the low elevation site because the air temperature at the high-elevation site is affected to a large extent by downward mixing of warm air near the ablation zone of the glacier during daytime. The air moisture content reflects the pronounced alternation of the wet and dry seasons, and the highest water vapor content is associated with the southwesterly Indian monsoon. The mean annual surface air temperature–elevation gradient is 0.72 ± 0.01 °C (100 m)⁻¹, and also shows a pronounced seasonal signature. Mean annual air temperatures have increased by about 0.62 °C per decade over the last 49 years in this region; the greatest warming trend is observed in winter, the smallest in summer. Warmer conditions have been observed since the mid-1980s. Additional studies have shown a reduction in precipitation in the 1960s that resulted in a decrease in net snow accumulation. Therefore, accelerated retreat of the Rongbuk Glacier since the 1980s may be caused by rising air temperature and the decreased precipitation.