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Abstract (from http://www.sciencedirect.com/science/article/pii/S1873965215000110): The goal of this study was to assess the importance of the 2007 sea ice retreat for hydrologic conditions on the Alaskan North Slope, and how this may have influenced the outbreak of tundra fires in this region. This study concentrates on two years, 2007 and 1996, with different arctic sea ice conditions and tundra fire activity. The year of 2007 is characterized by a low summer sea ice extent (second lowest) and high tundra fire activity, while 1996 had high sea ice extent, and few tundra fires. Atmospheric lateral boundary forcing from the NCEP/NCAR Reanalysis drove the Weather Research and Forecast (WRF) model, along with varying...
Abstract (from http://onlinelibrary.wiley.com/doi/10.1111/gcb.12875/abstract): Permafrost thaw can alter the soil environment through changes in soil moisture, frequently resulting in soil saturation, a shift to anaerobic decomposition, and changes in the plant community. These changes, along with thawing of previously frozen organic material, can alter the form and magnitude of greenhouse gas production from permafrost ecosystems. We synthesized existing methane (CH 4) and carbon dioxide (CO 2) production measurements from anaerobic incubations of boreal and tundra soils from the geographic permafrost region to evaluate large-scale controls of anaerobic CO 2 and CH 4 production and compare the relative importance...
Abstract (from http://onlinelibrary.wiley.com/doi/10.1002/2016EF000479/full): Glacier hypsometry provides a first-order approach for assessing a glacier's response to climate forcings. We couple the Randolph Glacier Inventory to a suite of in situ observations and climate model output to examine potential change for the ∼27,000 glaciers in Alaska and northwest Canada through the end of the 21st century. By 2100, based on Representative Concentration Pathways (RCPs) 4.5–8.5 forcings, summer temperatures are predicted to increase between +2.1 and +4.6°C, while solid precipitation (snow) is predicted to decrease by −6 to −11%, despite a +9 to +21% increase in total precipitation. Snow is predicted to undergo a pronounced...
The global mean surface temperature increased 0.85°C during the period 1880 – 2012. Some climate models predict an additional warming of up 2 to 4 ◦ C over the next 100 years for the primary breeding grounds for North American ducks. Such an increase has been predicted to reduce mid - continent breeding duck populations by >70%. Managing continental duck populations in the face of climate change requires understanding how waterfowl have responded to historical spatio - temporal climatic variation. However, such responses to climate may be obscured by how ducks respond to variation in land cover. We estimated effects of climate on settlement patterns of breeding ducks in the Prairie - Parkland Region (PPR), boreal...
Berry Risk Mapping and Modeling of Native and exotic defoliators in Alaska is a jointly funded project between the Alaska Climate Science Center and the North Pacific Landscape Conservation Cooperative.
Abstract: P-band interferometric synthetic aperture radar (InSAR) data at 5 m resolution from Kahiltna Glacier, the largest glacier in the Alaska Range, Alaska, USA, show pronounced spatial variation in penetration depth, δ P. We obtained δ P by differencing X- and P-band digital elevation models. δ P varied significantly over the glacier, but it was possible to distinguish representative zones. In the accumulation area, δ P decreased with decreasing elevation from 18±3 m in the percolation zone to 10±4 m in the wet snow zone. In the central portion of the ablation area, a location free of debris and crevasses, we identified a zone of very high δ P (34±4 m) which decreased at lower elevations (23±3 m in bare ice...
Abstract (from http://bioscience.oxfordjournals.org/content/65/5/499): Rates of glacier mass loss in the northern Pacific coastal temperate rainforest (PCTR) are among the highest on Earth, and changes in glacier volume and extent will affect the flow regime and chemistry of coastal rivers, as well as the nearshore marine ecosystem of the Gulf of Alaska. Here we synthesize physical, chemical and biological linkages that characterize the northern PCTR ecosystem, with particular emphasis on the potential impacts of glacier change in the coastal mountain ranges on the surface–water hydrology, biogeochemistry, coastal oceanography and aquatic ecology. We also evaluate the relative importance and interplay between interannual...
This 4-page publication was produced from the March 2013 Juneau Glacier Workshop. The publication describes the current understanding of the interconnected icefield, stream, and ocean systems that are such a dominant feature of coastal Alaska. The publication describes the state of research on glaciers and icefields, glacier ecology, and the role that glaciers play in ocean processes.
Abstract: To test the effects of altered hydrology on organic soil decomposition, we investigated CO2 and CH4 production potential of rich-fen peat (mean surface pH = 6.3) collected from a field water table manipulation experiment including control, raised and lowered water table treatments. Mean anaerobic CO2 production potential at 10 cm depth (14.1 ± 0.9 μmol C g-1 d-1) was as high as aerobic CO2 production potential (10.6 ± 1.5 μmol C g-1 d-1), while CH4 production was low (mean of 7.8 ± 1.5 nmol C g-1 d-1). Denitrification enzyme activity indicated a very high denitrification potential (197 ± 23 μg N g-1 d-1), but net reduction suggested this was a relatively minor pathway for anaerobic CO2 production. Abundances...
Abstract (from: http://www.igsoc.org/journal/60/221/j13J176.html): The Randolph Glacier Inventory (RGI) is a globally complete collection of digital outlines of glaciers, excluding the ice sheets, developed to meet the needs of the Fifth Assessment of the Intergovernmental Panel on Climate Change for estimates of past and future mass balance. The RGI was created with limited resources in a short period. Priority was given to completeness of coverage, but a limited, uniform set of attributes is attached to each of the ~198 000 glaciers in its latest version, 3.2. Satellite imagery from 1999–2010 provided most of the outlines. Their total extent is estimated as 726 800 +/- 34 000 km2. The uncertainty, about +/-...
Snow conditions are extremely important to a wide range of hydrologic and ecosystem components and processes, including those related to surface energy and moisture stores and fluxes, vegetation, mammals, birds, and fish. The required snow datasets currently do not exist at the required spatial and temporal resolutions needed by end users such as scientists, land managers, and policy makers.
Abstract (from http://onlinelibrary.wiley.com/doi/10.1002/hyp.9934/abstract): Adaptation planning in Alaska, as in other snowy parts of the world, will require snow projections, yet snow is a challenging variable to measure, simulate and downscale. Here we describe the construction and evaluation of 771-m-resolution gridded historical and statistically downscaled projections of snow/rain partitioning for the state of Alaska at decadal temporal resolution. The method developed here uses observational data to describe the relationship between average monthly temperature and the fraction of wet days in that month receiving snow, the snow-day fraction. Regionally and seasonally specific equations were developed to...
Abstract: Arctic tundra ecosystems have experienced unprecedented change associated with climate warming over recent decades. Across the Pan-Arctic, vegetation productivity and surface greenness have trended positively over the period of satellite observation. However, since 2011 these trends have slowed considerably, showing signs of browning in many regions. It is unclear what factors are driving this change and which regions/landforms will be most sensitive to future browning. Here we provide evidence linking decadal patterns in arctic greening and browning with regional climate change and local permafrost-driven landscape heterogeneity. We analyzed the spatial variability of decadal-scale trends in surface greenness...
Streamwater dissolved oxygen (DO) concentrations are driven by interacting physical and biotic parameters. Future DO depletion events in small, coastal salmon streams are therefore likely to be driven by changes in hydrology in addition to atmospheric warming. We measured DO, temperature, discharge and spawning salmon abundance in upstream (reference reach) and downstream salmon bearing reaches of four streams in southeast Alaska to determine how multiple physical and biotic factors interact to control streamwater DO. Stream temperature ranged from 5.1 to 15.8 °C and fell within the optimum range that is considered favorable for salmon physiology. Concentrations of DO ranged from 2.8 to 12.3 mg/L, with concentrations...
Abstract (from The Cryosphere): There is significant uncertainty regarding the spatiotemporal distribution of seasonal snow on glaciers, despite being a fundamental component of glacier mass balance. To address this knowledge gap, we collected repeat, spatially extensive high-frequency ground-penetrating radar (GPR) observations on two glaciers in Alaska during the spring of 5 consecutive years. GPR measurements showed steep snow water equivalent (SWE) elevation gradients at both sites; continental Gulkana Glacier's SWE gradient averaged 115 mm 100 m−1 and maritime Wolverine Glacier's gradient averaged 440 mm 100 m−1 (over > 1000 m). We extrapolated GPR point observations across the glacier surface using terrain...
Abstract (from http://onlinelibrary.wiley.com/doi/10.1002/2016GB005548/full): Burn area and the frequency of extreme fire events have been increasing during recent decades in North America, and this trend is expected to continue over the 21st century. While many aspects of the North American carbon budget have been intensively studied, the net contribution of fire disturbance to the overall net carbon flux at the continental scale remains uncertain. Based on national scale, spatially explicit and long-term fire data, along with the improved model parameterization in a process-based ecosystem model, we simulated the impact of fire disturbance on both direct carbon emissions and net terrestrial ecosystem carbon balance...
Abstract (from http://www.sciencedirect.com/science/article/pii/S0168192316303446): Across a global network of eddy covariance flux towers, two relatively new open-path infrared gas analyzers (IRGAs), the IRGASON and the EC150, are increasingly used to measure net carbon dioxide (CO2) fluxes (Fc_OP). Differences in net CO2 fluxes derived from open- and closed-path IRGAs in general remain poorly constrained. In particular, the performance of the IRGASON and the EC150 for measuring Fc_OP has not been characterized yet. These IRGAs measure CO2 absorption, which is scaled with air temperature and pressure before converting it to instantaneous CO2 density. This sensor-internal conversion is based on a slow-response thermistor...
Abstract (from RMetS): Synoptic‐scale patterns associated with daily temperature and precipitation extremes in Alaska are identified and evaluated for daily variability in order to understand consistency in forcing mechanisms associated with extreme events as well as the tendency for each pattern to produce an extreme event. Daily station data at five locations for the 29‐year period from 1982 to 2010 are used. The widely recognized ClimDex indices are used to identify extreme high temperature, low temperature, and single‐day precipitation events. Pressure patterns during extreme events are evaluated seasonally for summer (JJA) and winter (DJF) at mean sea level pressure, 700 and 500‐hPa geopotential heights. Temperature...
Abstract (from Wiley Online Library): Runoff from boreal hillslopes is often affected by distinct soil boundaries, including the frozen boundary and the organic-mineral boundary (OMB), where highly porous and hydraulically conductive organic material overlies fine-grained mineral soils. Viewed from the surface, ground cover appears as a patchwork on sub-meter scales, with thick, moss mats interspersed with lichen-covered, silty soils with gravel inclusions. We conducted a decameter-scale subsurface tracer test on a boreal forest hillslope in interior Alaska to quantify locations and mechanisms of transport and storage in these soils, focusing on the OMB. A sodium bromide tracer was added as a slug addition to a...
Abstract (from ScienceDirect): Indigenous peoples are increasingly developing Community-Based Monitoring programs to protect the waters and lands within their territories in response to multiple ecological and political stressors. Furthermore, CBM tends to focus on Indigenous peoples’ role as ‘knowledge holders.’ This paper explores CBM through a governance lens by understanding CBM as a strategy for the assertion of Indigenous sovereignty and jurisdiction. Research findings revealed that CBM is understood as both a method for generating data useful for decision-making and an expression of governance itself, rooted in understandings of stewardship, kinship and responsibility. Our findings also suggest that data...