Local mountain meteorology of the landscape around Longyearbyen in central Svalbard is analyzed through the decade from 2000 to 2011. Standard meteorological stations from close to sea level and up to 464 m a.s.l. located on different periglacial landforms, have been used. During winters with little sea ice, strong temperature inversions do not develop, and then there is a distinct cooling with height, as opposed to when sea ice is present. Airflow is accelerated due to topography and direction deflected in the confined valleys, whereas open plateaus have on average 1 m/s lower wind speeds with a regional SE direction. The permafrost thermal state is largely controlled by meteorology, with permafrost in the valley bottoms as cold as on the mountain plateaus. The periglacial landform most exposed to climatic variability is ice-wedges, which seem to crack mainly during shorter cooling periods. Such activity is also linked to temperature inversions, and thus also occur mainly when sea ice is present. Solifluction is mainly controlled by the balance between summer thawing and winter freezing in combination with snow dynamics, whereas avalanches are mainly wind controlled. Avalanches and avalanche controlled landforms are least sensitive to climatic variability.

We present the first glacier inventory of the Monte San Lorenzo region (47°35′S, 72°18′W) in the southern Patagonian Andes of Chile and Argentina. This region contains the largest and easternmost glaciers at these latitudes in South America. The inventory was developed using a combination of ASTER and Landsat ETM scenes from 2005 and 2008, respectively, and a semi-automatic band ratio approach to map glacier ice. Manual corrections were applied to include debris-covered ice and ice in cast shadows. We inventoried 213 glaciers that cover a 2005/2008 total area of ca. 207 km² and lie between 520 m and 3700 m in elevation. Landsat TM images acquired in 1985 and 2000 were subsequently used to assess changes in glacierized area over the 1985–2008 interval. Based on all available information, we determined an 18.6% reduction in the total glacier area since 1985. Glaciers smaller than 1 km² have shown highly variable (0–100%) relative areal reduction, whereas the formation and growth of proglacial lakes promoted rapid recession of the larger valley glaciers, which concentrate the major ice losses, representing ca. 32% of the total glacier area reduction. Glacier fragmentation has occurred for 50% of the ice bodies larger than 1 km². These results agree with the generalized pattern of glacier retreat observed throughout the Patagonian Andes, but the lack of detailed meteorological and glaciological data in the area preclude a more refined analysis of the climate-glacier relationships and processes explaining the recent glacier trends.

Alaska's arctic glaciers have retreated and thinned during recent decades, and glaciers in the central Brooks Range are no exception. Digital elevation models (DEMs) reconstructed from topographic maps (from 1970 and 1973) were differenced from a 2001 interferometric synthetic aperture radar DEM to calculate the volume and mass changes of 107 glaciers covering 42 km² (1970/1973) in the central Brooks Range, Alaska, U.S.A. For each glacier the 1970/1973 DEM was 3-D co-registered (horizontal and vertical) to maximize agreement between the non-glacierized terrains of both DEMs. Over the period 1970–2001, total ice volume loss was 0.69 ± 0.06 km³ corresponding to a mean (area-weighted) specific mass balance rate of -0.54 ± 0.05 m w.e. a^-1 (± uncertainty). The arithmetic mean of all glaciers' specific mass balance rates was -0.47 ± 0.27 m w.e. a^-1 (± 1 std. dev.). A value of -0.52 ± 0.36 m w.e. a^-1 (± 1 std. dev.) was found when 3-D coregistration is performed over the entire domain instead of individually for each glacier, indicating the importance of proper co-registration. Glacier area, perimeter, boundary compactness, mean elevation, and mean slope were correlated with specific balance rates, suggesting that large, low-elevation, elongated and shallow sloped glaciers had more negative balance rates than small, high-elevation, circular, and steep glaciers. A subsample of 36 glaciers showed a mean area reduction of 26 ± 16% (±1 std. dev.) over ∼35 years.

Physiological processes responsible for ecosystem carbon and nitrogen cycling may vary across hill slopes and be controlled by watershed hydrology and the associated nutrient transport. Mass transport of nutrients down slope and into water tracks may increase nutrient delivery to plant roots, nutrient uptake, and perhaps photosynthetic activity. Small arctic watersheds are commonly characterized by increased biomass, particularly of woody deciduous shrubs, both down slope and in water tracks. We ask if photosynthetic physiology varies with hill slope position and if it is correlated to observed changes in above ground biomass. Chlorophyll fluorescence surveys from six common species reveal that maximum photosynthetic electron transport decreased significantly (by as much as 85%) down slope in 4 species. Leaf nitrogen concentrations varied from 1 to 2.5% across all leaves sampled, but show little trend with hill slope position, and as a result are not well correlated with photosynthetic electron transport. We hypothesize that trace metal concentrations may have increased in the leaves of plants growing in down slope positions and that this may be responsible for the reduction in electron transport. The relationship between the measured maximum energy conversion by photosystem II and maximum electron transport rate is species specific and indicative of light adaptation in these arctic species. Increased plant growth down slope and in water tracks does not appear to be correlated to the physiological parameters measured and instead are more likely a product of increased canopy nitrogen concentrations and leaf area accumulation.

In this study, we use the coupled photosynthesis-stomatal conductance model of Collatz et al. (1991) to simulate the current canopy carbon dioxide exchange of a heterogeneous tundra ecosystem in European Russia. For the parameterization, we used data obtained from in situ leaf level measurements in combination with meteorological data from 2008. The modeled CO₂ fluxes were compared with net ecosystem exchange (NEE), measured by the eddy covariance technique during the snow-free period in 2008.

The findings from this study indicated that the main state parameters of the exchange processes were leaf area index (LAI) and Rubisco capacity (V_cmax). Furthermore, this ecosystem was found to be functioning close to its optimum temperature regarding carbon accumulation rates. During the modeling period from May to October, the net assimilation was greater than the respiration, leading to a net accumulation of 58 g C m^-2. The model results suggest that the tundra ecosystem could change from a carbon sink to a carbon source with a temperature rise of only 2–3 °C. This is due to the fact that, in the continental Arctic, a global warming of a few degrees might restrict the net assimilation, due to high temperatures, whereas the respiration is predicted to be enhanced. However, future changes in vegetation composition and growth, along with acclimation to the new thermal regime, might facilitate the assimilation to counterbalance the carbon losses.

Wildfires are historically infrequent in the arctic tundra, but are projected to increase with climate warming. Fire effects on tundra ecosystems are poorly understood and difficult to quantify in a remote region where a short growing season severely limits ground data collection. Remote sensing has been widely utilized to characterize wildfire regimes, but primarily from the Landsat sensor, which has limited data acquisition in the Arctic. Here, coarse-resolution remotely sensed data are assessed as a means to quantify wildfire burn severity of the 2007 Anaktuvuk River Fire in Alaska, the largest tundra wildfire ever recorded on Alaska's North Slope. Data from Landsat Thematic Mapper (TM) and downsampled Moderate-resolution Imaging Spectroradiometer (MODIS) were processed to spectral indices and correlated to observed metrics of surface, subsurface, and comprehensive burn severity. Spectral indices were strongly correlated to surface severity (maximum R2 = 0.88) and slightly less strongly correlated to substrate severity. Downsampled MODIS data showed a decrease in severity one year post-fire, corroborating rapid vegetation regeneration observed on the burned site. These results indicate that widely-used spectral indices and downsampled coarse-resolution data provide a reasonable supplement to often-limited ground data collection for analysis and long-term monitoring of wildfire effects in arctic ecosystems.

This study reflects the growing demand for better understanding the response of alpine lake ecosystems to climate forcing. We combined continuous monitoring of water temperature with GIS-derived data, and modeled the lake surface water temperature (LSWT) and ice-cover characteristics of 18 Tatra Mountains lakes against altitude, lake morphometry, and local topography. The general trend in LSWTs was similar across all studied lakes and showed a high degree of coherence over the whole study period. The daily LSWTs were governed primarily by altitude and topographic shading represented by lake-specific total duration of direct solar radiation (TDDSR). Day-to-day variability of LSWTs was controlled mainly by the maximum depth of the lakes. The surface temperature of deeper lakes was more stable than the temperature of shallow ones. Topographic shading appeared to play an important role in the development and duration of ice-cover. Lakes with low TDDSR retained ice-cover longer than well insolated ones.

This is the first time that the effect of topographic shading was explicitly considered in relation to the surface temperature and ice-cover timing of remote lakes. Including direct solar radiation as a model parameter would considerably improve predictions of temperature characteristics of high-altitude lakes. This may have potentially important implications for climate change studies as it could allow for site-specific modifications of temperatures in high-altitude lakes.

Cryosolic soils store large amounts of carbon (C) because soil organic matter (SOM) decomposition is slower than plant growth. The response of arctic SOM to climate change is likely to depend not only on temperature, but also upon complex interactions between soil properties and SOM chemistry. We hypothesized that organic surface soils (>17% carbon) have more labile SOM than mineral surface soils (<17% carbon). Furthermore, we hypothesized that high arctic soils have more labile SOM than soils from the Low Arctic and subarctic. This study was conducted in 3 arctic ecosystems: subarctic (Churchill, Manitoba; n = 138), Low Arctic (Daring Lake, Northwest Territories;n = 60), and High Arctic (Truelove Lowlands, Nunavut; n = 54). The 0–10 cm depth of several different Cryosolic soils was sampled. The results from density fractionation and solid-state ¹³C cross polarization and magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectroscopy showed that organic surface soils contained relatively more labile C than mineral surface soils. Organic soils contained about 13% more O-Alkyl-C and 30% less Aromatic-C than mineral soils. Furthermore, for Churchill, Daring Lake, and Truelove organic soils, 53, 73, and 20% of the C was included in the light fraction of SOM [LF (LF < 1.55 g mL^-1)], whereas 24, 19, and 14% of the C was included in the LF of mineral soils, respectively. Organic surface soils of subarctic and low arctic sites contained relatively more labile C than the high arctic site. Results showed that the subarctic and low arctic sites store about 15% more O-alkyl-C and 35% less Aromatic-C than high arctic organic soils (P < 0.001).

Deciduous plants in the Arctic are increasing in abundance due to warming trends, and this increase will likely contribute to changes in regional carbon dynamics. One of the dominant deciduous-shrub genera, Salix, is highly susceptible to leaf galls, but the influence of arthropod herbivores on plant-level carbon uptake in the Arctic remains poorly studied. We examined the impacts of galling by two eriophyoid mites on a suite of ecophysiological traits in leaves of two species of willows (Salix pulchra Cham, and Salix glauca L.) in Alaskan arctic tundra. Galled leaves showed significant declines in maximum photosynthetic capacity (Amax), photosystem II efficiency (F_V /F_M), stomatal conductance (g_s), and instantaneous water-use efficiency (WUE) in S. pulchra leaves and in A_max and F_v/F_M of S. glauca leaves. Neighboring gall-free leaves on the same shoot as galled leaves had higher A_max and g_sthan nearby controls suggesting compensatory responses. Gall-infested tissue had significantly higher concentrations of glucose and fructose compared to gallfree leaves, suggesting a possible preference for these metabolites. Alternatively, this variation in metabolite concentrations in the area of wounding may be associated with the production of defense compounds. To unravel the specific variation in metabolic concentrations related to gall infestation, additional studies are needed. Our findings do suggest that galling mites—ubiquitous but poorly examined in the tundra—have significant impacts on photosynthetic processes that are likely to affect whole-plant functioning in arctic willows.

Average depth of snow in the mountains of southeastern Australia is decreasing at a rate of 0.48 cm a^-1, while the duration of the snowpack has been shortened by 18.5 days since 1954 ( -3 days per decade). The major factors responsible for these declines are an increasing temperature trend of 0.36 °C per decade, and a reduction in winter precipitation at the rate of 10.1 mm a^-1. While the depth of the snowpack is dependent upon precipitation trends and minimum temperatures (multiple r²= 0.43), the shortening in the length of the snow period is best predicted by increasing temperatures and reduced humidity. The major forcing of the warming trend involves greenhouse gasses, in particular atmospheric carbon dioxide and water vapor. However, the decline in winter precipitation seems to be unrelated to the forcing of greenhouse gasses, and is instead statistically associated with the Southern Oscillation Index (r = 0.38). Inverse correlations were found between depth of snow and solar irradiance, which in turn is inversely correlated with the number of sunspots per cycle. The latter findings suggest that the declining precipitation and snow trends could additionally be associated with a reduction in solar activity during the past five decades.

Plant waxes (e.g. long-chain n-alkanes) in ice cores are a promising paleovegetation proxy. However, much work needs to be done to assess how n-alkanes are transported from source areas to, and incorporated into, glacial archives. In this paper we present analyses of n-alkanes in seasonal snow and assess the information on source vegetation. n-Alkanes with carbon numbers C₁₈ to C₄₃ were extracted from snow samples collected at two sites in Hokkaido, northern Japan, during winter 2009–2010. Molecular distributions revealed that the majority of the n-alkanes originated from higher vegetation (ca. 65%), rather than anthropogenic sources. The distribution characteristics confirmed that the n-alkane signal had a wide regional origin, rather than a local source. We determined stable carbon and hydrogen isotopic compositions for the C₂₇ n-alkane. The δ¹³C of the C₂₇ ( -28.2 to -33.0‰) was more representative of C₃ than C₄ vegetation, while the δD of the C₂₇ (- 169.9 to -223.1‰) indicated growth latitudes more northerly than Hokkaido. The n-alkanes in the snow preserve information about the source vegetation type (photosynthetic group, growth site), confirming that if deposited with seasonal snows that firnify to form glacial ice, they have potential to record broad, regional vegetation changes over time.

The reliability of Cassiope tetragona as temperature proxy might be restricted by influence on growth of precipitation and amount of Photosynthetically Active Radiation (PAR). Carbon-13 discrimination (Δ) in C₃-plants is generally influenced by temperature and precipitation and can therefore potentially record important additional climatic information.

We doubled precipitation and reduced PAR ( -43%), during four and two growing seasons, respectively, at a high arctic site in Svalbard. Differences in discrimination in leaves from separate light, and thus temperature, regimes (sun-facing and soil-facing leaves) were also assessed. A Δ-chronology (1975–2008) in annual shoot length increments was developed.

C. tetragona growth did not respond to enhanced precipitation and only slightly to PAR-reduction. Discrimination against carbon-13 was stronger in leaves and shoots receiving extra precipitation and weaker in sun-exposed leaves compared to soil-facing leaves. The annual climate signal in the Δ-chronology was strongly smoothed by secondary radial growth.

Our results show that the temperature signal in C. tetragona is hardly disturbed by changes in summer precipitation or PAR, which confirms its suitability as temperature proxy. The experimental evidence for the sensitivity of carbon-13 discrimination in C. tetragona to precipitation and temperature changes shows its potential as proxy for hydrological changes in the polar semi-desert.

To understand the dependence of glacial features on precipitation, glacier behavior was simulated under different precipitation conditions using a glacier fluctuation model that combined a mass-balance model with a glacier flow model. The results reveal a strong dependence of glacier behavior on precipitation conditions. Glacier volume changes in accordance with both precipitation seasonality and annual precipitation amount. Glacier volume also fluctuates in response to changes in precipitation seasonality even if no change in annual precipitation amount occurs, because of changes in glacier albedo and the volume that is able to accumulate. Furthermore, the accumulation area ratio (AAR) depends not only on the annual precipitation amount, but also on precipitation seasonality. These relationships should be considered when the AAR method is used to reconstruct the past equilibrium line of glaciers. Glacier reactions to temperature change become more sensitive as the amount of annual precipitation increases. Response time is different for each glacier type defined by precipitation seasonality: the winter-precipitation-seasonality type had the longest response time, and the summer-precipitation-seasonality type had the shortest. The difference in the response time of glacier types is larger under arid conditions and smaller under humid conditions. The simulation results in this study underscore the importance of including glacier response to precipitation conditions when estimating glacier reactions to climate change.