A5025043779- Climate change and permafrost
- Geology and Paleoclimatology Research
- Cryospheric studies and observations
- Economic Theory and Institutions
- Economic Theory and Policy
- Economic theories and models
- Peatlands and Wetlands Ecology
- Indigenous Studies and Ecology
- Geological Studies and Exploration
- Political Economy and Marxism
- Arctic and Antarctic ice dynamics
- Botany and Plant Ecology Studies
- Lichen and fungal ecology
- Rangeland and Wildlife Management
- Methane Hydrates and Related Phenomena
- Atmospheric and Environmental Gas Dynamics
- Botany, Ecology, and Taxonomy Studies
- Arctic and Russian Policy Studies
- Geological formations and processes
- Auditing, Earnings Management, Governance
- Species Distribution and Climate Change
- Ecology and Vegetation Dynamics Studies
- Philosophy, Science, and History
- Tree-ring climate responses
- Pleistocene-Era Hominins and Archaeology
University of Alaska Fairbanks
2016-2025
Indiana University of Pennsylvania
1989-2019
Australian National University
1976-2012
Monash University
2012
The University of Melbourne
2012
University of Alaska System
1983-2011
New York Botanical Garden
2006
Russian Academy of Sciences
2006
Cold Regions Research and Engineering Laboratory
1982-2005
United States Geological Survey
1982-2005
A major challenge in predicting Earth's future climate state is to understand feedbacks that alter greenhouse-gas forcing. Here we synthesize field data from arctic Alaska, showing terrestrial changes summer albedo contribute substantially recent high-latitude warming trends. Pronounced Alaska correlates with a lengthening of the snow-free season has increased atmospheric heating locally by about 3 watts per square meter decade (similar magnitude regional expected over multiple decades...
Abstract. Question: What are the major vegetation units in Arctic, what is their composition, and how they distributed among bioclimate subzones countries? Location: The Arctic tundra region, north of tree line. Methods: A photo‐interpretive approach was used to delineate onto an Advanced Very High Resolution Radiometer (AVHRR) base image. Mapping experts within nine regions prepared draft maps using geographic information technology (ArcInfo) portion these were later synthesized make final...
Large variations in the composition, structure, and function of Arctic ecosystems are determined by climatic gradients, especially growing‐season warmth, soil moisture, snow cover. A unified circumpolar classification recognizing five types tundra was developed. The geographic distributions vegetation north 55°N, including position forest limit types, could be predicted from climatology using a small set plant functional embedded biogeochemistry‐biogeography model BIOME4. Several...
Abstract Linkages between diminishing Arctic sea ice and changes in terrestrial ecosystems have not been previously demonstrated. Here, the authors use a newly available Normalized Difference Vegetation Index (NDVI) dataset (a measure of vegetation photosynthetic capacity) to document coherent temporal relationships near-coastal ice, summer tundra land surface temperatures, productivity. The find that, during period satellite observations (1982–2008), within 50 km coast early breakup...
Between 60,000 and 40,000 B.P., northeastern Queensland, south New South Wales, southeastern Australia were drier than at present. From 40,000–30,000 B.P. a colder climate present is indicated from one Guinea area. Dryness became even more accentuated in whereas many lakes filled up the southern mainland, probably because of increasing precipitation effectiveness there. Before end this period conditions now already giving rise to slope instability Snowy Mountains Wales. The 25,000–15,000 saw...
Abstract Climate warming in regions of ice‐rich permafrost can result widespread thermokarst development, which reconfigures the landscape and damages infrastructure. We present multisite time series observations couple ground temperature measurements with development a region very cold permafrost. In Canadian High Arctic between 2003 2016, anomalously warm summers caused mean thawing indices to be 150–240% above 1979–2000 normal resulting up 90 cm subsidence over 12‐year observation period....
Numerous studies have evaluated the dynamics of Arctic tundra vegetation throughout past few decades, using remotely sensed proxies vegetation, such as normalized difference index (NDVI). While extremely useful, these coarse-scale satellite-derived measurements give us minimal information with regard to how changes are being expressed on ground, in terms structure and function. In this analysis, we used a strong regression model between NDVI aboveground phytomass, developed from extensive...
Land cover maps are the basic data layer required for understanding and modeling ecological patterns processes. The Circumpolar Arctic Vegetation Map (CAVM), produced in 2003, has been widely used as a base map studies arctic tundra biome. However, relatively coarse resolution vector format of were not compatible with many other sets. We present new version CAVM, building on strengths original map, while providing finer spatial resolution, raster format, improved mapping. Raster CAVM uses...
Vegetation productivity trends for the Arctic tundra are updated 1982–2011 period and examined in context of land surface temperatures coastal sea ice. Understanding mechanistic links between vegetation climate parameters contributes to model advancements that necessary improving projections. This study employs remote sensing data: Global Inventory Modeling Mapping Studies (GIMMS) Maximum Normalized Difference Index (MaxNDVI), Special Sensor Microwave Imager (SSM/I) sea-ice concentrations,...
Abstract. Soils in Arctic and boreal ecosystems store twice as much carbon the atmosphere, a portion of which may be released high-latitude soils warm. Some uncertainty timing magnitude permafrost–climate feedback stems from complex interactions between ecosystem properties soil thermal dynamics. Terrestrial fundamentally regulate response permafrost to climate change by influencing surface energy partitioning itself. Here we review how processes influence dynamics these linkages evolve...
Here we analyzed a time series of 21‐yr satellite data for three bioclimate subzones in northern Alaska and confirmed long‐term trend increase vegetation greenness the Alaskan tundra that has been detected globally latitudes. There was 16.9% (±5.6%) peak across region corresponded to simultaneous increases temperatures. We also examined changes four specific types using an 11‐yr finer resolution (1‐km) found temporal time‐integrated were greatest areas moist nonacidic tundra. These between...
A unified scheme to assign pollen samples vegetation types was used reconstruct patterns north of 55°N at the last glacial maximum (LGM) and mid‐Holocene (6000 years B.P.). The data set assembled for this purpose represents a comprehensive compilation based on work many projects research groups. Five tundra (cushion forb tundra, graminoid prostrate dwarf‐shrub erect low‐ high‐shrub tundra) were distinguished mapped basis modern surface samples. tundra‐forest boundary distributions boreal...
Three 60 m long, 2·8 high snowfences have been erected to study long-term effects of changing winter snow conditions on arctic and alpine tundra. This paper describes the experimental design short-term effects. Open-top fiberglass warming chambers are placed along gradients in controls areas outside fences; each plot is paired with an unwarmed plot. The purpose experiment examine short- changes integrated physical-biological systems under simultaneous regime summer temperature, as part...
Arctic landscapes have visually striking patterns of small polygons, circles, and hummocks. The linkages between the geophysical biological components these systems their responses to climate changes are not well understood. “Biocomplexity Patterned Ground Ecosystems” project examined patterned‐ground features (PGFs) in all five bioclimate subzones along an 1800‐km trans‐Arctic temperature gradient northern Alaska northwestern Canada. This paper provides overview transect illustrate trends...
Active-layer thickness was mapped over a 26,278-km2 area of northern Alaska containing complex and highly variable patterns topography, vegetation, soil properties. Procedures included frequ...
Abstract. We present the first vegetation analysis from Arctic Foothills of northern Alaska according to Braun‐Blanquet approach. The data are Imnavait Creek and Toolik Lake regions. focus on associations dry mesic upland surfaces moderate snow accumulation sites; other plant communities, i.e. those blockfields, non‐sorted circles, water tracks, briefly described. Summary floristic information is presented in a synoptic table. Five 15 community types tentatively placed into seven existing...
Abstract Many areas of the Arctic are simultaneously affected by rapid climate change and industrial development. These likely to increase in number size as sea ice melts abundant natural resources become more accessible. Documenting changes that have already occurred is essential inform management approaches minimize impacts future activities. Here, we determine cumulative geoecological effects 62 years (1949–2011) infrastructure‐ climate‐related Prudhoe Bay Oilfield, oldest most extensive...
Carbon dioxide concentrations through snow were measured in different arctic tundra communities on the North Slope of Alaska during winter and early spring 1996. Subnivean CO 2 always higher than atmospheric . A steady state diffusion model was used to generate conservative estimates flux atmosphere. The magnitude efflux differed with community type, rates carbon release increased from March May. Winter highest riparian bed lowest dry heath, upland tussock, wet sedge communities. Snow...