Search

With the EU-funded PACE (Permafrost and Climate in Europe) project at the turn of this century, several deep boreholes (100 m +) were drilled in European mountain sites, including in mainland Norway, Svalbard and Sweden. During other projects from 2004 and the International Polar Year (IPY) period in 2006–2007, several additional boreholes were drilled in different sites in both Norway and Iceland, measuring temperatures along both altitudinal and latitudinal gradients. At most sites, multi-temporal geophysical soundings are available using electrical resistivity tomography (ERT). Here, we study the development of permafrost and ground temperatures in mainland Norway and Iceland based on these data sets. We document that permafrost in Norway and Iceland is warming at a high rate, including the development of taliks in both Norway and Iceland in response to global climate change during the last 20 years. At most sites, ground surface temperature (GST) is apparently increasing more strongly than surface air temperature (SAT). Changing snow conditions appear to be the most important factor for the higher GST rates. Modelling exercises also indicate that the talik development can be explained by both higher air temperatures and increasing snow depth. [ABSTRACT FROM AUTHOR]

Soil temperature and moisture are important regulators of a broad range of biotic and abiotic processes in terrestrial ecosystems. Vegetation can, in turn, play a role in regulating soil microclimate, which creates potential for powerful and interactive feedbacks from soil and vegetation on the atmosphere. Although the regulatory effect of vegetation on soil microclimatic conditions has been quite extensively and empirically assessed, most studies have determined the net effect of intact woody vegetation versus bare ground. However, for other plant functional groups we lack a clear understanding of their role and any climate‐context dependency in controlling microclimatic conditions. We investigated the role of three major plant functional groups – graminoids, forbs and bryophytes – in regulating soil microclimate in semi‐natural alpine grasslands. Using a fully factorial above‐ground biomass removal experiment, we assessed the role of these plant functional groups in regulating soil temperature amplitude, soil moisture, and number of freezing days. The experiment was replicated across orthogonal temperature and precipitation gradients in Norway to assess whether the effects of functional group abundance varied with climate. The effect of plant biomass on soil microclimate varied among functional groups across the climatic gradients. Bryophytes reduced growing season soil temperature, whereas graminoids and forbs did not (0.5ºC compared to 0ºC), and with a stronger effect in colder climates at higher elevations and on days with high solar radiation. Bryophyte biomass further reduced the number of soil freezing days at boreal and sub‐alpine sites. Finally, graminoid biomass partly explained variation in soil moisture: soils dried more under graminoids at drier sites. Our findings highlight that functional group identity plays a key role in regulating soil microclimate in alpine grasslands across seasons. The strong effect of bryophytes on soil temperature points to their importance in the plant community for a variety of ecosystem functions, some of which may be indirectly vulnerable to future warming via biomass reductions of bryophytes. [ABSTRACT FROM AUTHOR]

• A climate-driven model for stream flow and E. coli discharge into an ungauged drinking water source is implemented. • Forest canopy and soil organic carbon content control runoff generation in temperate mountain catchments. • Instream sediment processes mostly control the occurrence of E. coli in streams. • Snowmelt induced peak stream flows in the temperate mountain catchments will occur earlier in winter in future. • Future shifts in stream flow will potentially lower concentrations of faecal indicator bacteria in surface water resources. The discharge of fecal indicator bacteria into surface water sources poses treatment challenges to drinking water utilities. Changes in the discharge regimes of streams resulting from extreme precipitation associated with climate change can exacerbate these challenges. The catchments of many surface water sources depended upon by water treatment plants are ungauged, thus making it difficult to predict the impacts of climate change on the microbial quality of such water sources. In this study, a hydrological model is implemented to assess the impact of local climate projections on flow regimes and E. coli discharge in the ungauged catchment of the drinking water source for the city of Ålesund in Norway. We performed separate sensitivity analysis for flow and E. coli, and assessed the variations in patterns of flow and E. coli concentrations in the streams in future using adjusted meteorological data. The calibrated flow showed good agreement with the observed data, but the E. coli model yielded lower performance indices. The results indicate that interception of precipitation by forest cover and soil organic carbon content mostly control flow generation in the catchments, and the variations in the concentrations of E. coli were more sensitive to instream sediment processes. Flow levels in the streams would remain the same in 2045 and 2075. Peak flows that currently occur in spring and autumn months may respectively shift back to winter and summer months. High concentrations of E. coli currently observed in summer in the streams may be lower in future, but the concentrations may be high at the start of autumn seasons. The results have management implications for watersheds and water utilities mostly in temperate climate regions. [ABSTRACT FROM AUTHOR]

Contemporary hillslope processes are extremely varied and are driven by a number of diverse physical, chemical, and biological processes. These processes span a wide range of spatial and temporal scales and are considered to react sensitively to climatic changes, anthropogenic impacts and other disturbances.We present ongoing GFL research activities focussing on environmental drivers of rockwall retreat, and denudational hillslope processes in a cold climate mountain environment (western Norway) and in a Mediterranean mountain setting (eastern Spain). In detail, we explore the influence of (i) lithological and structural characteristics, (ii) the rockwall temperature regime and (iii) the connected relative importance of physical-, chemical- and biological processes on weathering and resultant morphologies under these two contrasting climates. Special focus is on possible effects of ongoing and accelerated climate change and on the question how these effects differ under the two distinct climates. Our research is conducted on selected hillslope systems within two tributary valleys (max. elevation 2083 m a.s.l.) located on the western side of the Jostedalsbreen ice cap within the fjord landscape of western Norway. The lithology consists primarily of Precambrian granitic orthogneisses. The climate (slightly above sea level) is cool temperate oceanic with a mean annual air temperature of ca. 6°C and an annual precipitation sum of 1100 mm. January and February are the coldest months with mean monthly air temperatures below 0°C. Higher elevations are characterized by a distinct winter frost regime and a several months lasting closed snow cover. Maximum summer temperatures (June, July) are rarely exceeding 25°C but rockwalls having a favourable exposition can receive a rather high solar radiation. The selected hillslope systems in eastern Spain (Calpe) are located within the Sierra de Bernia mountains (max. elevation 1126 m a.s.l.) which consist of glauconitic and bioclastic marine limestones with alterations of marl. The area is characterized by a mild Mediterranean climate with a mean annual air temperature of ca. 18°C and an annual precipitation sum around 400 mm (slightly above sea level). During the coldest months (January, February) it can be comparably cold even with frost and snow in the mountains although they are situated close to the coast. In contrast, maximum summer temperatures (July, August) can easily exceed 30°C and south-facing rockwalls are exposed to a high solar radiation. Our investigations encompass detailed geological and geomorphologial mapping, the identification and monitoring of the most relevant hillslope processes in combination with detailed statistical analysis of meteorological data. The monitoring programme includes installed nets for collecting freshly accumulated rockfall debris, installed tracer lines and remote time-laps cameras for monitoring various mass transfers as well as near-surface and surface rockwall temperature sensors for monitoring the thermal rockwall regime.An improved and more comprehensive understanding of how different environmental factors interact and control hillslope processes under two contrasting and changing climates is expected to be essential for predicting possible effects of ongoing climate change in sensitive mountain environments. [ABSTRACT FROM AUTHOR]