Beschreibung: One of the consequences of warming climate is rising ground temperatures and degradation of perennially frozen ground, permafrost. Thawing of near-surface permafrost can cause geohazards, such as ground subsidence, thaw settlement and thermokarst, potentially harmful to nature and human activity in the Arctic. This dataset contains high-resolution raster grids of near-future permafrost extent and geohazard potential for the Northern Hemisphere permafrost areas. Ground temperature was predicted with statistical models employing geospatial data on environmental conditions at 30 arc-second resolution (~1 km2). These predictions, together with data on factors affecting permafrost stability, were used to formulate geohazard indices. Using climate-forcing scenarios (Representative Concentration Pathways 2.6, 4.5 and 8.5), permafrost extent and hazard potential were projected for the 2041–2060 and 2061–2080 time periods. The resulting dataset consists of seven permafrost (extent during 2000–2014 and the six future scenarios) and 24 geohazard maps in GeoTIFF format.

Beschreibung: This dataset contains spatial predictions of the potential environmental spaces for pingos, ice-wedge polygons and rock glaciers across the Northern Hemisphere permafrost areas. The potential environmental spaces, i.e. conditions where climate, topography and soil properties are suitable for landform presence, were predicted with statistical ensemble modelling employing geospatial data on environmental conditions at 30 arc-second resolution (~1 km). In addition to the baseline period (1950-2000), the predictions are provided for 2041-2060 and 2061-2080 using climate-forcing scenarios (Representative Concentration Pathways 4.5 and 8.5). The resulting dataset consists of five spatial predictions for each landform in GeoTIFF format. The data provide new information on 1) the fine-scale spatial distribution of permafrost landforms in the Northern Hemisphere, 2) the potential future alterations in the environmental suitability for permafrost landforms due to climate change, and 3) the circumpolar distribution of various ground ice types, and can 4) facilitate efforts to inventory permafrost landforms in incompletely mapped areas.

Beschreibung: The presence of ground ice in Arctic soils exerts a major effect on permafrost hydrology and ecology, and factors prominently into geomorphic landform development. As most ground ice has accumulated in near-surface permafrost, it is sensitive to variations in atmospheric conditions. Typical and regionally widespread permafrost landforms such as pingos, ice-wedge polygons, and rock glaciers are closely tied to ground ice. However, under ongoing climate change, suitable environmental spaces for preserving landforms associated with ice-rich permafrost may be rapidly disappearing. We deploy a statistical ensemble approach to model, for the first time, the current and potential future environmental conditions of three typical permafrost landforms, pingos, ice-wedge polygons and rock glaciers across the Northern Hemisphere. We show that by midcentury, the landforms are projected to lose more than one-fifth of their suitable environments under a moderate climate scenario (RCP4.5) and on average around one-third under a very high baseline emission scenario (RCP8.5), even when projected new suitable areas for occurrence are considered. By 2061–2080, on average more than 50% of the recent suitable conditions can be lost (RCP8.5). In the case of pingos and ice-wedge polygons, geographical changes are mainly attributed to alterations in thawing-season precipitation and air temperatures. Rock glaciers show air temperature-induced regional changes in suitable conditions strongly constrained by topography and soil properties. The predicted losses could have important implications for Arctic hydrology, geo- and biodiversity, and to the global climate system through changes in biogeochemical cycles governed by the geomorphology of permafrost landscapes. Moreover, our projections provide insights into the circumpolar distribution of various ground ice types and help inventory permafrost landforms in unmapped regions.

Beschreibung: Current analyses and predictions of spatially‐explicit patterns and processes in ecology most often rely on climate data interpolated from standardized weather stations. This interpolated climate data represents long‐term average thermal conditions at coarse spatial resolutions only. Hence, many climate‐forcing factors that operate at fine spatiotemporal resolutions are overlooked. This is particularly important in relation to effects of observation height (e.g. vegetation, snow and soil characteristics) and in habitats varying in their exposure to radiation, moisture and wind (e.g. topography, radiative forcing, or cold‐air pooling). Since organisms living close to the ground relate more strongly to these microclimatic conditions than to free‐air temperatures, microclimatic ground and near‐surface data are needed to provide realistic forecasts of the fate of such organisms under anthropogenic climate change, as well as of the functioning of the ecosystems they live in. To fill this critical gap, we highlight a call for temperature time series submissions to SoilTemp, a geospatial database initiative compiling soil and near‐surface temperature data from all over the world. Currently this database contains time series from 7538 temperature sensors from 51 countries across all key biomes. The database will pave the way towards an improved global understanding of microclimate and bridge the gap between the available climate data and the climate at fine spatiotemporal resolutions relevant to most organisms and ecosystem processes.

Beschreibung: Ground ice dynamics bear crucial importance in the hydrologic and ecologic development of permafrost landscapes, but also create characteristic landforms. So far, spatial distributions and sensitivities of these landforms under changing climates have not been assessed at a circumpolar scale. We integrated pingo (n = 9,709), ice-wedge polygon (n = 861) and rock glacier (n = 4,035) observations and geospatial data on environmental conditions into a statistical modelling framework to produce high-resolution (~1km2) distribution maps of permafrost landform occurrence across the Northern Hemisphere in current and future climates. We found that on average more than one-fifth of the potential environmental spaces might be lost by mid-century under a moderate human-induced greenhouse emission forcing (representative concentration pathway, RCP4.5). Thereon, environmental spaces continue to shrink to less than 50% of the current coverage by 2061–2080, given a ‘business-as-usual’ (RPC8.5) climate-forcing scenario. Forecasted losses of suitable regions for pingos and ice-wedge polygons were attributed to increases in precipitation and thawing-season air temperatures. Rock glaciers were dominantly air temperature-driven. Our results are congruent with the site- and regional-scale observations of rapid geomorphic responses to ongoing climate change, and for the first time demonstrate large regional shifts in potential landform distributions at a circumpolar scale. These findings suggest that extensive regions are undergoing drastic changes in Earth surface processes, e.g. ground ice thaw, which are prone to cause thermokarst and threats to infrastructure development. Despite sophisticated modelling frameworks and increased data availability, circumpolar-scale geomorphological distribution modelling is still highly dependent on the quality of used geospatial data and the completeness of sampling, especially in heterogeneous environments. Based on the magnitude of climatic sensitivities of permafrost landforms, we suggest that geomorphic responses should be closely integrated into assessments of climate change impacts on natural and human systems.

Beschreibung: The regional variability in tundra and boreal carbon dioxide (CO2) fluxes can be high, complicating efforts to quantify sink-source patterns across the entire region. Statistical models are increasingly used to predict (i.e., upscale) CO2 fluxes across large spatial domains, but the reliability of different modeling techniques, each with different specifications and assumptions, has not been assessed in detail. Here, we compile eddy covariance and chamber measurements of annual and growing season CO2 fluxes of gross primary productivity (GPP), ecosystem respiration (ER), and net ecosystem exchange (NEE) during 1990–2015 from 148 terrestrial high-latitude (i.e., tundra and boreal) sites to analyze the spatial patterns and drivers of CO2 fluxes and test the accuracy and uncertainty of different statistical models. CO2 fluxes were upscaled at relatively high spatial resolution (1 km2) across the high-latitude region using five commonly used statistical models and their ensemble, that is, the median of all five models, using climatic, vegetation, and soil predictors. We found the performance of machine learning and ensemble predictions to outperform traditional regression methods. We also found the predictive performance of NEE-focused models to be low, relative to models predicting GPP and ER. Our data compilation and ensemble predictions showed that CO2 sink strength was larger in the boreal biome (observed and predicted average annual NEE −46 and −29 g C m−2 yr−1, respectively) compared to tundra (average annual NEE +10 and −2 g C m−2 yr−1). This pattern was associated with large spatial variability, reflecting local heterogeneity in soil organic carbon stocks, climate, and vegetation productivity. The terrestrial ecosystem CO2 budget, estimated using the annual NEE ensemble prediction, suggests the high-latitude region was on average an annual CO2 sink during 1990–2015, although uncertainty remains high.