Alaska North Research Articles

Increasing Methane Emissions and Widespread Cold‐Season Release From High‐Arctic Regions Detected Through Atmospheric Measurements

AbstractRising Arctic temperatures pose a threat to the large carbon stores trapped in Arctic permafrost. To assess methane emissions in high‐Arctic regions, we analyzed atmospheric data from Alaska and Siberia using two methods: (a) a wind sector approach to calculate emission changes based on concentration enhancements using wind direction, and (b) an inversion method utilizing a high‐resolution atmospheric transport model. Incorporating data after 2015, we observed a significant rise in methane emissions (0.018 ± 0.005 Tg yr−2 from 2000 to 2021) from Alaska's North Slope, indicating a shift from previous analyses. We find 34%–50% of yearly emissions occurred in the late season (September–December) consistently across multiple years and regions, which is historically underestimated in models and inventories. Our findings reveal significant changes occurring in the Arctic, highlighting the crucial role of long‐term atmospheric measurements in monitoring the region, especially during the cold season.

Willow Project Socialization As An Introduction To Petroleum Engineering At Yos Sudarso Metro High School

The Willow Project is located on Alaska's north slope, within the National Petroleum Reserve, which is held by the United States federal government. Based on the topics being discussed, a strong desire was developed, particularly among Yos Sudarso Metro High School students, to learn about the causes for oil drilling, as well as the impacts and benefits of drilling from diverse perspectives. Concerning the community service that according to Willow Project theme, the lecturers as the facilitators of this community service assisted students who wanted to find a solution to the Willow Project issue, where they hoped that there would be several points regarding the impact and benefits of academia in the energy sector, particularly petroleum engineering. As a result of socialization regarding the Willow Project drilling, impacts and benefits have been imparted in the Community Service activities, which are separated into environmental impacts, climate impacts, and social impacts. Following an overview of the impact of the Willow Project drilling, the benefits of the drilling are explained, including job creation and economic benefits, energy independence, and tax revenue. The crux of the impacts and benefits given is that it is still envisaged that fossil energy would be used to increase jobs in the nearby community and globally. Aside from that, it is desired that the development of renewable energy, the reduction of drilling in conservation areas, and the preservation of environmental integrity would continue.

EOR of heavy oil polymer on Alaska's North Slope: History matching challenges and solutions in a significant long-term water cut reduction

In 2016, a pilot program in Alaska's Milne Point Field tested polymer flooding for heavy oil recovery. Using four wells in the Schrader Bluff reservoir, it aimed to assess its effectiveness in capturing heavy oil resources. Generally, polymer flooding can boost oil production by 10-15%, typically occurring 6-9 months after injection. However, in this case, it took over 24 months for a polymer breakthrough. The method proved highly effective, consistently reducing water content by over 40% and maintaining a low level below 20% for 18 months. Applying standard simulation methods, like history matching, became challenging due to this prolonged low water cut. The usual history-matching processes focus on relative permeability, permeability corrections, and skin effect modifications. Nevertheless, these alternatives proved ineffective. In response to the extended low water cut in Alaska's North Slope, a unique approach was suggested. This approach entails highlighting the low-end point (Krw) across multiple relative permeability curves and adjusting these values according to the water cut history. Additionally, the method takes into account permeability adjustments, Equation of State on analyzes of oil viscosity, J-function incorporation, and considers the potential for viscous fingering during the process. The pilot program displayed remarkable polymer flooding effectiveness, but its unique performance on the North Slope required a modified history-matching approach to simulate its success accurately.

Adoption and adaptation in Iñupiat fashion: Past and present

This article presents and discusses the development of Iñupiat (North Alaskan Inuit) fashion of atikłuk (‘inner garment’) and atigi (‘outerwear’) over time, with a focus on adoption and adaptation, linked to the concept of cultural authentication. It is based on the author’s fieldwork in the winter of 1997 and the summer of 1998, which included participant observations and interviews with seamstresses from the Iñupiat villages of Kaktovik and Utqiaġvik at the North Slope of Alaska, literature reviews, observations from museums and archival photos. The second part of this article involves a case study that focuses on a young Iñupiat trans woman and her mother in 2022. Together they designed a new fabric (instead of leather) for an atikłuk. The case show how she adopts the contemporary Iñupiat garment and adapts it to her own style.

Universal thermal climate index in the Arctic in an era of climate change: Alaska and Chukotka as a case study

The modern unambiguous climate change reveals in a rapid increase of air temperature, which is more distinctly expressed in the Arctic than in any other part of the world, affecting people health and well-being. The main objective of the current research is to explore the inter- and intra-annual changes in thermal stress for people in the Arctic, specifically for two parts of Beringia: Alaska, USA, and Chukotka, Russia, using climatology of the universal thermal climate index (UTCI). Data for 39 locations are taken from the ERA5-HEAT reanalysis for the period 1979–2020. Climatologically, the study area is divided into four subregions in Alaska: North, Interior, West and South, and two in Chukotka: Interior and Coast. The extreme coldest UTCI categories (1 and 2) are most common in coastal locations of northern Alaska and Chukotka, where strong winds exacerbate the low temperatures during winter. The results show that the frequency of category 1 (UTCI<−40°C) varies spatially from a quarter of all hours annually in Alaska North to almost zero in Alaska South. On the other hand, the warmest categories are rarely reached almost everywhere in Alaska and Chukotka, and even categories 7 and 8 (UTCI between +26 and +38°C) are found occasionally only at interior locations. Category 6 with no thermal stress (UTCI between +9 and+26°C) has frequencies up to 3% and 25% in Alaska North and Interior, respectively. The extremely cold thermal stress frequencies have substantially decreased over the 1979–2020 period, especially in Alaska North and Chukotka Coast. At the same time, the number of hours with UTCI in the comfortable category of thermal perception has increased depending on subregion, from 25 to 203 h/year. Overall, a decrease in the UTCI categories of extremely cold stress is coupled with an increase in the comfortable range in both Alaska and Chukotka. The salient conclusion is that, from the point of view of comfort and safety, global warming has a positive impact on the climatology of thermal stress in the Arctic, providing advantages for the development of tourism and recreation.

New secondary metabolites produced by Paraphoma radicina FB55 as potential antifungal agents.

Microorganisms in specific environments are rich sources of bioactive natural products as they produce compounds that can aid their survival in harsh environments. In an effort to investigate antifungal compounds produced by microorganisms, the fungal strain Paraphoma radicia FB55, isolated from a marine sediment of the Beaufort Sea, north of Alaska, was subjected to chemical investigation. Chromatography of the culture extracts yielded two new compounds (1 and 2) and eight known compounds (3-10). Their structures were determined using spectroscopic and chemical methods. Compound 1 was a new analog of the known compound (3) with an isobenzofuranone skeleton. The absolute configuration of the chiral center in 1 was established by comparison of its ECD and specific rotation values with those for a known analogue. Compound 2 is a polyketide-amino acid hybrid. Comprehensive Nuclear Magnetic Resonance (NMR) analysis indicated that 2 consisted of two substructures:5-methyl-6-oxo-2,4-heptadienoic acid and isoleucinol. The absolute configuration of the isoleucinol moiety in 2 was determined to be D using Marfey's method. All the isolated compounds were evaluated for antifungal activities. Although the antifungal activity of the isolated compounds was not potent, co-treatment of compounds 7 and 8 with a clinically available amphotericin B (AmB) lowered the IC50 values of AmB by synergism against human pathogenic yeast.

Distribution and morphometry of pingos, western Canadian Arctic, Northwest Territories, Canada

Pingos of the western Canadian Arctic (WCA) coastal plain are among the most abundant and well-studied in the northern hemisphere. However, the abundance and morphometric variation of these pingos has not been quantitatively examined with respect to surficial and physiographic settings, likely because they have never been systematically catalogued with precision. We assess the distribution and morphology of pingos in the WCA using the High Resolution Digital Elevation Model (HRDEM) and demonstrate how this population compares to others in the Arctic, and how it varies in relation to surficial and physiographic settings. Of the 2363 pingos identified in the WCA (900 more than previous estimates), relief ranges from a few 10s of centimetres to 46.7 m for Ibyuk Pingo, which is the archetype of closed-system (hydrostatic) pingos in the region. Nearly 18 % (272) are taller than 10 m, although about 35 % of the pingos (830) are <2 m tall, which is the minimum height limit of most other studies. Using this minimum cut-off to compare populations, the mean height of WCA pingos >2 m (n = 1533) is 6.5 m, which is greater than other lowland pingos in the Arctic. WCA pingos are about 10 % larger in radius than pingos in North Alaska but have comparable mean slopes. Nevertheless, about 72 % of WCA pingos >2 m tall are “high-slope” pingos with a mean slope of 5° or greater. Within the WCA, 95 % of all pingos occur within the Tuktoyaktuk Lowlands in relation to the distribution of underlying Pleistocene sands, specifically the extent of braidplain deposits from the paleo-Peel and Anderson rivers known as the Kidluit Formation (Marine Isotope Stage 3). However, the spatial density of pingos within the Tuktoyaktuk Lowlands varies with physiography, and the highest densities relate to ice-rich, topographically-complex terrains that have a history of glaciation and thermokarst. In contrast, pingos within the modern Mackenzie Delta, where the low-lying, Holocene-age terrain is not amenable to lake drainage that promotes closed-system pingo formation, have a low density (5 % of total population) and are smaller. Nearly 30 % of WCA pingos reside at <5 m asl. Consequently, ongoing relative sea level rise and the effects on coastal change are likely to erode some pingos within the current population but may also trigger lake drainage and formation of new pingos.

Retrogressive thaw slumps in the Alaskan Low Arctic may influence tundra shrub growth more strongly than climate

AbstractThermokarst disturbance in permafrost landscapes is likely to increase across the tundra biome with climate warming, resulting in changes to topography, vegetation, and biogeochemical cycling. Tundra shrubs grow on permafrost, but shrub–thermokarst relationships are rarely studied in detail. Since the 1980s, Alaska's North Slope has experienced increased thermokarst activity, including retrogressive thaw slumps (RTSs) on hillslopes. Within decades, RTSs near Toolik Lake, Alaska, were colonized by tall (≥0.5 m) deciduous shrubs. We used dendrochronology methods on 66 shrubs (182 stem cross sections) representing dominant deciduous species: willows (Salix pulchra and S. glauca) and dwarf birch (Betula nana) at two RTS chronosequences on Alaska's North Slope comprising seven sites, to quantify thermokarst and climate effects (25 years of temperature and precipitation records) on shrub secondary growth (i.e., annual rings) in RTS‐disturbed and undisturbed moist acidic tussock (MAT) tundra. Across species, average growth ring widths were two times wider for shrubs in RTSs than in MAT, and ring widths decreased with RTS age. A 1°C June temperature increase was associated with 2% wider rings across species and sites, but shrubs showed marginal growth in warmer summers, supporting tundra‐wide shrub climate sensitivity studies. A 4.5% average ring width increase per 1 mm of previous year's September precipitation was seen in shrubs in mid‐successional RTSs, suggesting protective effects of early snowfall in RTSs versus open tundra. Retrogressive thaw slump age category explained 47% and 30% of average ring width variance of willows and dwarf birch, respectively, in linear mixed‐effects models. Climate variables explained 2% average ring width variance across species. Our results suggest that RTS exerts strong successional effects on tundra shrub growth. Climate effects appear to show weaker synoptic patterns across the study area. Retrogressive thaw slumps will likely contribute to tundra greening where RTS activity is increasing.

Permafrost Degradation Impacts on the Trans-Alaska Pipeline

The Trans-Alaska Pipeline System transports warm crude oil over 800 miles through a 4-ft-diameter pipeline (i.e., the “mainline”) from Prudhoe Bay on Alaska's North Slope to the Valdez Marine Terminal on the Gulf of Alaska. TAPS traverses three major mountain ranges, several active faults, and continuous and discontinuous permafrost terrain. Permafrost is generally defined as ground that remains at or below 32°F for at least two consecutive years. Permafrost with temperatures between 32°F and 30°F is generally referred to as “warm permafrost,” while permafrost with temperatures below 30°F is referred to as “cold permafrost.”

Frequency of Winter Coupled North Pacific/North America Circulation Regimes

The jet stream over North America alternates between a more zonal direction and a wavy pattern (a more meridional flow) associated with persistent blocking patterns. To better understand these important patterns, we base our study on the frequency of winter (November–February) events during 1981–2020, based on four circulation regime types: blocking, the Alaskan Ridge, North American Ridge/Pacific Wave-Train; and zonal, the Pacific Trough and the central Pacific High/Arctic Low (Amini and Straus 2019). Increased information on within and between season variability is important, as the impacts of blocking include the California heatwave and mid-continent or east coast cold spells. Rather than extensive pattern duration or significant trends, temporal variability is the major feature. In some years the combination of the Alaskan Ridge and North American Ridge/Pacific Wave-Train patterns represent ~5 major events covering 35 days of the 120-day winter period, with individual events lasting 10 days. Within-season multiple occurrences and short durations dominate the winter meteorology of the continental United States. The characterization of the persistence of these blocking events is relevant for extended range forecasts.

Characterization of site‐specific vegetation activity in Alaskan wet and dry tundra as related to climate and soil state

AbstractWe present discrete (2‐h resolution) multi‐year (2008–2017) in situ measurements of seasonal vegetation growth and soil biophysical properties from two sites on Alaska's North Slope, USA, representing dry and wet sedge tundra. We examine measurements of vertical active soil layer temperature and soil moisture profiles (freeze/thaw status), woody shrub vegetation physiological activity, and meteorological site data to assess interrelationships within (and between) these two study sites. Vegetation phenophases (cold de‐hardening start, physiological function start, stem growth start, stem growth end, physiological function end, cold hardening completion) were found to have greater interannual day of year (DOY) occurrence variability at the dry site compared with the wet site. At the dry site, vegetation activity begins on average ~7 days earlier and ends ~11 days earlier. The mean active stem growth window lasts ~54 days for the dry site and ~51 days for the wet site. Vegetation, in both tundra environments, began cold de‐hardening functions (warm season prep) prior to atmospheric temperatures warming above 0°C. Similar results were found related to the critical soil freeze/thaw/transition dates; the dry site had a DOY phenophase occurrence range that was 8 days larger than that of the wet site. A longer continuous summer thaw period was captured at the wet site by ~26 days throughout the active layer. In addition, the dry site was measured to have longer spring and fall soil isothermal conditions than the wet site by ~9 and 5 days throughout the active layer. These results show that the dry site's willow shrub vegetation physiology and soil condition phenology is more variable than the wet site. Alongside the in situ data, a remote sensing product from NASA's MEaSUREs program was utilized; our research indicates that the AMSR‐derived satellite product is more precise over the wet tundra site with critical date alignment between remote sensing observations and in situ measurements ranging from ~4 to 11 days. Furthermore, the AMSR product was shown to preemptively estimate land surface condition change during the spring transition for both tundra types while lagging during the fall transition and freeze‐up periods.

Genetic variation in sea otters (Enhydra lutris) from the North Pacific with relevance to the threatened Southwest Alaska Distinct Population Segment

AbstractFor the sea otter (Enhydra lutris), genetic population structure is an area of research that has not received significant attention, especially in Southwest Alaska where that distinct population segment has been listed as threatened since 2005 pursuant to the U.S. Endangered Species Act. In this study, 501 samples from 14 locations from Prince William Sound, Alaska to the Commander Islands in Russia were analyzed for variation at 13 microsatellite loci. Our results indicate a high degree of genetic divergence among the 14 locations (FST = 0.120) with gene flow conforming to the isolation by distance (IBD) model (r2 = 0.491, p &lt; .05). The 14 sampling locations formed six geographic associations in clustering and ordination analyses that likely correspond to remnant population lineages: (1) Southcentral Alaska, (2) Kodiak and North Alaska Peninsula, (3) South Alaska Peninsula and Bristol Bay, (4) Eastern Aleutian, (5) Western Aleutian, and (6) the Commander Islands. Except for South Alaska Peninsula and Bristol Bay, these clusters closely agree with previously defined stock and management unit boundaries. Our results reveal significant genetic population structure and are generally congruent with current management strategies for the threatened Southwest Alaska distinct population segment.

Rapid range expansion predicted for the Common Grackle (Quiscalus quiscula) in the near future under climate change scenarios

BackgroundClimate change due to anthropogenic global warming is the most important factor that will affect future range distribution of species and will shape future biogeographic patterns. While much effort has been expended in understanding how climate change will affect rare and declining species we have less of an understanding of the likely consequences for some abundant species. The Common Grackle (Quiscalus quiscula; Linnaeus 1758), though declining in portions of its range, is a widespread blackbird (Icteridae) species in North America east of the Rocky Mountains. This study examined how climate change might affect the future range distribution of Common Grackles.MethodsWe used the R package Wallace and six general climate models (ACCESS1-0, BCC-CSM1-1, CESM1-CAM5-1-FV2, CNRM-CM5, MIROC-ESM, and MPI-ESM-LR) available for the future (2070) to identify climatically suitable areas, with an ecological niche modelling approach that includes the use of environmental conditions.ResultsFuture projections suggested a significant expansion from the current range into northern parts of North America and Alaska, even under more optimistic climate change scenarios. Additionally, there is evidence of possible future colonization of islands in the Caribbean as well as coastal regions in eastern Central America. The most important bioclimatic variables for model predictions were Annual Mean Temperature, Temperature Seasonality, Mean Temperature of Wettest Quarter and Annual Precipitation.ConclusionsThe results suggest that the Common Grackle could continue to expand its range in North America over the next 50 years. This research is important in helping us understand how climate change will affect future range patterns of widespread, common bird species.

Snowier winters extend autumn availability of high‐quality forage for caribou in Arctic Alaska

AbstractCaribou (Rangifer tarandus) rely on the short Arctic growing season to restore body condition, support the demands of lactation, and prepare for the long arctic winter, making them susceptible to even small changes in forage availability or quality. Body condition in the summer and autumn is linked to winter survival rates and fecundity in cows, critical factors in the productivity of caribou populations. Climate change predictions of warmer and wetter northern winters suggest increased snowfall over Alaska's North Slope, which has recently been verified between 1995 and 2017. However, a comprehensive analysis of how deeper snow will affect caribou forage quality is absent across Alaska. In this study, we quantify how snow depth alters the quality and seasonality of caribou forage using a long‐term (24 yr) International Tundra Experiment snow depth manipulation to evaluate how winter climate change scenarios may affect tussock tundra systems in northern Alaska. Deeper snow in prior winters leads to increases in growing season leaf N and digestible protein (DP) in deciduous shrubs (Salix spp. and Betula spp.) and graminoids (Carex spp. and Eriophorum spp.), but not evergreen dwarf shrubs (Rhododendron spp. and Vaccinium spp.). Dry matter digestibility varied among species with small differences (&lt;5%) associated with snow depth. Most striking was the discovery that deeper snow in the prior winter increased the duration of DP levels above the minimum threshold for protein gain in caribou by as much as 25 d in Salix pulchra and 6–9 d in Betula nana and Carex bigelowii in late summer and early autumn. Consequently, deeper winter snow may provide an extended window of opportunity for foraging and the accumulation of lean body mass and fat reserves which promote winter survival and successful calving the following spring and potentially improve the productivity of caribou in northern Alaska.

Long‐term hydrological, biogeochemical, and ecological data for the Kuparuk River, North Slope, Alaska

AbstractThe Kuparuk River, located on Alaska's North Slope, is one of the most studied rivers in the Arctic. For nearly 40 seasons, physical, chemical, and biological parameters have been monitored continuously in a 5 km, 4th‐order reach of the river during the short summer season when there is flow in this river. Flow decreases as the tundra begins to refreeze in the late autumn and these streams normally remain frozen until the spring freshet. The monitoring program has supported a 34‐year phosphorus enrichment experiment conducted by the Arctic Long Term Ecological Research (LTER) program. Enrichment with phosphorus dramatically changed the structure and function of the primary producer community in the fertilized reach, with cascading effects in higher trophic levels. The datasets generated by this experiment have revealed significant increases in flow‐weighted mean concentrations of nitrate and significant decreases in flow‐weighted mean concentrations of dissolved organic N and P over time. In this paper, we present an overview of the nutrient concentration, discharge, macroinvertebrate, and Arctic grayling population datasets we have collected. The purposes of these datasets are to track changes resulting from the enrichment experiment, support ancillary research on responses of an Arctic stream to climate warming and permafrost thaw, and to provide input and validation data for models to predict future changes in Arctic streams.

North Alaska Super Basin: Petroleum systems of the central Alaskan North Slope, United States

North Alaska Super Basin oil fields have produced more than 18 billion bbl of oil with at least 5 billion bbl remaining in existing fields, and estimated yet-to-find resources exceed 10 billion bbl in three prolific petroleum systems. Since discovery of the two largest United States conventional oil fields at Prudhoe Bay and Kuparuk River in the 1960s, technological advancements including three-dimensional seismic data with amplitude vs. offset analysis, horizontal and extended reach drilling, and identification of source rocks for light oils have enabled new discoveries including Willow and Pikka. Oil in the Prudhoe Bay field is interpreted as a mixture cosourced by lateral migration from Triassic Shublik Formation shale and carbonate, Lower Cretaceous highly radioactive zone (HRZ) shale, and Lower Jurassic Kingak Shale. The bulk properties of Prudhoe Bay main field oils are consistent with the modeled oil composition expelled within the fetch area, and the presence or quality of carrier beds apparently did not affect oil migration efficiency. The Shublik Formation is interpreted as the oil source for Kuparuk River field, the HRZ shale is interpreted as the oil source for Tarn field, and the Kingak Shale is interpreted as the oil source for Alpine field. Point McIntyre field is interpreted as sourced by the same three source rocks as Prudhoe Bay field, and Fiord field is interpreted as cosourced from Shublik and Kingak. West Sak field is interpreted as a mixture of moderately biodegraded oil that spilled from the Prudhoe Bay field and lightly biodegraded condensate that leaked from the underlying Kuparuk River field.

Greenhouse gas fluxes from Alaska's North Slope inferred from the Airborne Carbon Measurements campaign (ACME-V)

Northern high latitudes are likely to be heavily impacted by climate change, changes that will undoubtedly alter carbon cycling across these regions. An understanding of both the magnitude and drivers of current CO2 and CH4 fluxes are a prerequisite for making robust projections of future changes. In this study, we use observations from the recent Airborne Carbon Measurements (ACME-V) aircraft campaign to estimate the magnitude and environmental predictors CO2 and CH4 fluxes in Alaska. ACME-V consisted of 38 flights across the North Slope between late May and mid-September 2015, making it the most detailed airborne survey of northern Alaska to date. These data, combined with a geostatistical inverse model, provide a unique lens into fluxes across the region. Using this approach, we estimate a large CO2 flux to the atmosphere from the North Slope of Alaska in early summer that is counterbalanced by CO2 uptake in late summer; this balance between early season respiration and late-summer photosynthesis drives the total summer CO2 flux across northern Alaska during the study period. We further compare our results to process-based flux estimates (the Terrestrial Model Intercomparison Project, MsTMIP and the Wetland and Wetland CH4 Inter-comparison of Models Project, WETCHIMP) and several recent studies of the same spatial domain. We observe a similarity in CO2 flux totals between MsTMIP suite of models and our study (June 2015–0.86 – 0.57 vs 0.96, July 2015 MsTMIP −1.01 – 0.00 vs −0.14 and August 2915 MsTMIP −0.73 – 0.29 vs −0.50 μmol m−2 s−1, MsTMIP and our study, respectively, averaged across the North Slope). However, we find significantly higher CH4 fluxes from the North Slope than any of the WETCHIMP models. Specifically, we estimate total CH4 fluxes from the North Slope of Alaska of +0.64 ± 0.13 Tg (95% confidence), during June through August 2015 while the WETCHIMP model estimates range from 0.004 to 0.1 Tg, depending upon the model. Furthermore, the contribution of the North Slope tundra to the overall Alaskan CH4 fluxes during the entire period was ~27%, compared to 3% in state-of-the-art process-based models.

Estimating the Audibility of Industrial Noise to Denning Polar Bears

ABSTRACTOil and gas activities on Alaska's North Slope overlap spatially with polar bear (Ursus maritimus) maternal denning habitat and temporally with the peri‐partum and emergence periods. Noise associated with these activities can be substantial and concerns regarding the effects on polar bears have been acknowledged. But the secluded and ephemeral nature of subnivean maternal dens renders the measurement of behavioral and physiological responses of bears to noise exposure challenging, except for rare cases when disturbance‐prompted den abandonment has been documented. These limitations, coupled with the uncertainty associated with the synergistic effects of anthropogenic activities on bears in a rapidly changing Arctic, prompt the need to develop predictive models of disturbance to ensure management guidelines effectively mitigate disturbance. Towards this end, we characterized noise propagation from 9 sources (2 aircraft, 2 over‐tundra tracked vehicles, 4 wheeled on‐road vehicles, and humans walking) used to support industrial activities around artificial snow dens near Milne Point, Alaska, USA, in March–April 2010. We built dens in 4 configurations to mimic variability in den roof thickness and to evaluate differences in noise propagation from when the den was closed compared to being open, similar to den emergence. We integrated these data with an existing polar bear audiogram and developed models to predict auditory‐detection probabilities as a function of distance from the den. Within a closed den, aircraft had high probabilities (detection probability ≥75%) of being detected by polar bears at distances ≤1.6 km and ground‐based sources had high probabilities of detection at distances ≤0.8 km. On average, closed dens reduced noise levels by 15 decibels (dB) relative to open dens. Our findings indicate that although polar bear snow dens effectively attenuate acoustic sound pressure levels, noise from some industrial support vehicles was likely to be detected farther from dens than previously documented. These results reinforce the importance of maintaining buffer zones around polar bear dens to minimize the potential for den disturbance. © 2020 The Wildlife Society.

Nomenclature changes in the "Entolomatoid fungi of western North America and Alaska" (Largent 1994)

Nomenclatural omissions and orthographic errors in my 1994 monograph are corrected. The three genera Calliderma, Clitopiloides, and Fibropilus were validly published in 1994 as stat. nov. based on infrageneric names, and their extraterritorial basionym type species are proposed here as Ca. callidermum comb. nov., Cl. cyathus comb. nov., and F. fumosifolius comb. nov. Names originally proposed as provisional are validated as Leptonia cyanea comb. nov., L. cyanea var. occidentalis var. nov., and Inocephalus appressus sp. nov. Nolanea names that were illegitimate later homonyms are proposed as N. undatomarginata comb. nov. and N. papillatoides comb. nov., based on published replacement names. The published validation of the invalid 1994 name "Leptonia violacea" is indicated, and seven orthographic epithet corrections are listed

Akunik Pass, Chukchi Sea Coast, North Alaska, June 1974

Akunik Pass, Chukchi Sea Coast, North Alaska, June 1974