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An 11 to 13-year-old Arctic Wolf (Canis lupus arctos) was observed chasing a young Arctic Hare (Lepus arcticus) for 6 to 7 minutes and catching it. This provides an example of the degree of endurance of which an old wolf is capable.
Observed declines in the Arctic sea ice have resulted in a variety of negative effects on polar bears ( Ursus maritimus ). Projections for additional future declines in sea ice resulted in a proposal to list polar bears as a threatened species under the United States Endangered Species Act. To provide information for the Department of the Interior's listing-decision process, the US Geological Survey (USGS) produced a series of nine research reports evaluating the present and future status of polar bears throughout their range. In response, Armstrong et al. [Armstrong, J. S., K. C. Green, W. Soon. 2008. Polar bear population forecasts: A public-policy forecasting audit. Interfaces 38 (5) 382–405], which we will refer to as AGS, performed an audit of two of these nine reports. AGS claimed that the general circulation models upon which the USGS reports relied were not valid forecasting tools, that USGS researchers were not objective or lacked independence from policy decisions, that they did not utilize all available information in constructing their forecasts, and that they violated numerous principles of forecasting espoused by AGS. AGS (p. 382) concluded that the two USGS reports were "unscientific and inconsequential to decision makers." We evaluate the AGS audit and show how AGS are mistaken or misleading on every claim. We provide evidence that general circulation models are useful in forecasting future climate conditions and that corporate and government leaders are relying on these models to do so. We clarify the strict independence of the USGS from the listing decision. We show that the allegations of failure to follow the principles of forecasting espoused by AGS are either incorrect or are based on misconceptions about the Arctic environment, polar bear biology, or statistical and mathematical methods. We conclude by showing that the AGS principles of forecasting are too ambiguous and subjective to be used as a reliable basis for auditing scientific investigations. In summary, we show that the AGS audit offers no valid criticism of the USGS conclusion that global warming poses a serious threat to the future welfare of polar bears and that it only serves to distract from reasoned public-policy debate.
We conducted aerial surveys of Lesser Snow Geese ( Chen caerulescens caerulescens ) during autumn staging on the coastal plain of the Arctic National Wildlife Refuge (ANWR) in northeast Alaska from late August through September, 1982 - 1993. We evaluated numbers and distribution of Snow Geese that staged on the ANWR, compared abundance of birds among 5 x 5-km cells used frequently (5 - 8 yr), periodically (3 - 4 yr), or infrequently (1 - 2 yr), and examined distribution changes within years. Maximum numbers of Snow Geese observed annually were highly variable (range 12,828 - 309,225). Snow Goose flocks occurred across 605,000 ha of the coastal plain, but used some areas more frequently than others. Frequently used cells (38 of 363 cells in the study area) were non-randomly distributed and primarily occurred on the central coastal plain between the wet coastal and steep foothills regions. Abundance of geese was greatest in frequently used, intermediate in periodically used, and lowest in infrequently used cells. Within years, Snow Goose numbers and flock locations varied between surveys, possibly because geese moved to different foraging areas during staging. The widespread distribution and annual variability in numbers of Snow Geese on the coastal plain was likely because birds used foraging habitats that were spatially and temporally heterogeneous. The ANWR coastal plain is an important component of the fall-staging area used by Snow Geese that nest in the western Canadian Arctic. Management decisions that affect the region should reflect its value to migrating Snow Geese.
Beaufortian strata (Jurassic-Lower Cretaceous) in the National Petroleum Reserve in Alaska (NPRA) are a focus of exploration since the 1994 discovery of the nearby Alpine oil field (>400 MMBO). These strata include the Kingak Shale, a succession of depositional sequences influenced by rift opening of the Arctic Ocean Basin. Interpretation of sequence stratigraphy and depositional facies from a regional two-dimensional seismic grid and well data allows the definition of four sequence sets that each displays unique stratal geometries and thickness trends across NPRA. A Lower to Middle Jurassic sequence set includes numerous transgressive-regressive sequences that collectively built a clastic shelf in north-central NPRA. Along the south-facing, lobate shelf margin, condensed shales in transgressive systems tracts downlap and coalesce into a basinal condensed section that is likely an important hydrocarbon source rock. An Oxfordian-Kimmeridgian sequence set, deposited during pulses of uplift on the Barrow arch, includes multiple transgressive-regressive sequences that locally contain well-winnowed, shoreface sandstones at the base of transgressive systems tracts. These shoreface sandstones and overlying shales, deposited during maximum flooding, form stratigraphic traps that are the main objective of exploration in the Alpine play in NPRA. A Valanginian sequence set includes at least two transgressive-regressive sequences that display relatively distal characteristics, suggesting high relative sea level. An important exception is the presence of a basal transgressive systems tract that locally contains shoreface sandstones of reservoir quality. A Hauterivian sequence set includes two transgressive-regressive sequences that constitute a shelf-margin wedge developed as the result of tectonic uplift along the Barrow arch during rift opening of the Arctic Ocean Basin. This sequence set displays stratal geometries suggesting incision and synsedimentary collapse of the shelf margin.
The African-Eurasian Waterbird Agreement (AEWA; http://www.unep-aewa.org/) calls for means to manage populations which cause conflicts with certain human economic activities. The Svalbard population of the pink-footed goose has been selected as the first test case for such an international species management plan to be developed. This document describes progress to date on the development of an adaptive harvest management (AHM) strategy for maintaining pink-footed goose abundance near their target level by providing for sustainable harvasts in Norway and Denmark. This briefing supplements material provided in the Progress Summary distributed to the International Working Group on February 1, 2013. We emphasize that peer review is an essential aspect of the process of developing and implementing an AHM program for pink-footed geese, and we will continue to solicit reviews by the International Working Group and their staff, as well as scientists not engaged in this effort. We wish to make the Working Group aware the the following two manuscripts have been submitted recently to refereed journals and are available upon request from the senior authors: Jensen, G.H., J. Madsen, F.A. Johnson, and M. Tamstorf. Snow conditions as an estimator of the breeding output in high-Arctic pink-footed geese Anser brachyrhynchus. Polar Biology: In review. Johnson, F.A., G.H. Jensen, J. Madsen, and B.K. Williams. Uncertainity, robustness, and the value of information in managing an expanding Arctic goose population. Ecological Modeling: In review. In addition to these manuscripts, the Progress Summary (February 1, 2013), and this Briefing Summary (April 23, 2013) an annual report will be produced in August 2013 and every summer thereafter. Additional manuscripts for journal publication are also anticipated.
On 11 January 2006, Mount Augustine volcano in southern Alaska began erupting after 20- year repose. The Anchorage Forecast Office of the National Weather Service (NWS) issued an advisory on 28 January for Kodiak City. On 31 January, Alaska Airlines cancelled all flights to and from Anchorage after multiple advisories from the NWS for Anchorage and the surrounding region. The Alaska Volcano Observatory (AVO) had reported the onset of the continuous eruption. AVO monitors the approximately 100 active volcanoes in the Northern Pacific. Ash clouds from these volcanoes can cause serious damage to an aircraft and pose a serious threat to the local communities, and to transcontinental air traffic throughout the Arctic and sub-Arctic region. Within AVO, a dispersion model has been developed to track the dispersion of volcanic ash clouds. The model, Puff, was used operational by AVO during the Augustine eruptive period. Here, we examine the dispersion of a volcanic ash (or aerosol) cloud from Mount Augustine across Alaska from 29 January through the 2 February 2006. We present the synoptic meteorology, the Puff predictions, and measurements from aerosol samplers, laser radar (or lidar) systems, and satellites. Aerosol samplers revealed the presence of volcanic aerosols at the surface at sites where Puff predicted the ash clouds movement. Remote sensing satellite data showed the development of the ash cloud in close proximity to the volcano consistent with the Puff predictions. Two lidars showed the presence of volcanic aerosol with consistent characteristics aloft over Alaska and were capable of detecting the aerosol, even in the presence of scattered clouds and where the ash cloud is too thin/disperse to be detected by remote sensing satellite data. The lidar measurements revealed the different trajectories of ash consistent with the Puff predictions. Dispersion models provide a forecast of volcanic ash cloud movement that might be undetectable by any other means but are still a significant hazard. Validation is the key to assessing the accuracy of any predictions. The study highlights the use of multiple and complementary observations used in detecting the trajectory ash cloud, both at the surface and aloft in the atmosphere.
During an April 22, 2006, interview on the CBC radio program “The House,” Tim Flannery, author of the recent book “The Weathermakers,” stated, “Projections of the polar bear specialists are that by about 2030, around that date, the species will be extinct because of global warming induced changes in the Arctic sea ice.” That statement was followed on May 4th by quotations in the Toronto Globe and Mail from Dr. Mitch Taylor, a polar bear researcher in Nunavut, Canada, claiming, “polar bears have survived both warmer times and colder times than these,” that “nothing has melted the Arctic sea ice for 30 million years,” that “polar bears are remarkably adaptable,” and that “a warming climate might even benefit polar bears.”
Chlorinated paraffins (CPs) are complex mixtures of polychlorinated n-alkanes categorized according to their carbon chain length: short chain (SCCPs, C10 – C13), medium (C14 - C17), and long chain (C>17), chlorinated paraffins. SCCPs are primarily used in metalworking applications, as flame retardants, and in paints, adhesives, sealants, textiles, plastics and rubber (UNEP 2012). In 2012, the United Nations Environment Program (UNEP 2012) reported in the Revised Draft Risk Profile for SCCPs, that CPs were produced in the United States, the European Union (EU), Slovakia, Brazil, India, Japan and China. While annual global consumption of SCCPs is large (>25 tonnes/year), it has sharply declined over the past 20 years. SCCPs are released through wastewater, landfills, and air emissions (UNEP 2012). Concentrations of SCCPs have been reported in fish and marine mammals in North and South America, Europe, Japan, Greenland and the Arctic (UNEP 2012 and references therein). Characterization of SCCP concentrations and exposure in terrestrial wildlife is limited. In 2010, SCCP concentrations were reported in the eggs of yellow-legged gulls (Larus michahellis) (4536 ± 40 pg/g wet weight (ww)) and Audouin’s gulls (Larus audouinii) (6364 ± 20 pg/g ww) in Spain (Morales et al. 2012), and little auks (Alle alle) (5 - 88 ng/g ww) and kittiwakes (Rissa tridactyla) (5 - 44 ng/g ww) in the European Arctic (Reth et al. 2006). In Sweden, muscle of ospreys contained CPs of unspecified chain length (Jansson et al. 1993). Although the toxicity of SCCPs has been demonstrated in aquatic invertebrates, fish, frogs, and laboratory rats, there are limited avian studies and these reported no effects of SCCPs on egg parameters of domestic hens (Gallus gallus domesticus) and ducks (Anas platyrhynchos) (UNEP 2012). Despite reported accumulation of SCCPs in wild birds, to our knowledge, exposure-related toxicities and effects with respect to avian wildlife remain unknown.
Recent research has shown that Forward Looking Infia-Red (FLIR) imagery can detect polar bear dens despite total snow cover over their deming habitat. FLIR imagers detect a AT or difference in temperature between objects in the imager's field of view. During the Arctic winter, the groundlsnow surface is typically cold, providing a dark background in the FLIR imager. Sources of heat appear as lighter or white areas. Dens, in particular, appear as small bright "hotspots", usually with kzy boundaries (Appendix 1). Most commonly, since bears chose deep snow drifts for deming, dens can be distinguished from the normally dark (cold) band of drifted snow surrounding them. This innovation has the potential to prevent human activities fiom disturbing deming polar bears by allowing managers to discover dens before potentially disruptive activities begin. This is important because expanding resource extraction in Alaska's Arctic regions may threaten the welfare of polar bears and their habitat. In recent years, exploration and development activities have expanded east and west of the original oil fields of Prudhoe Bay. Hydrocarbon extraction is now occurring or planned along much of the central Beaufort Sea coast. As development continues into the National Petroleum Reserve, the scope of expansion could include 213 of the northern coastal region of Alaska. Industrial activities are a potential threat to polar bears, especially as they might disturb bears in maternal dens (Lentfer and Hensel 1980, Stirling 1990, Stirling and Andriashek 1992, Amstrup 1993, Amstrup and Gardner 1994). As the number of humans and their activities have increased in recent years, there has been a concurrent increase in the number of female polar bears deming on land (Amstrup and Gardner 1994). Therefore, the probability of disrupting maternal deming can be expected to increase in the future. Using FLIR surveys to detect bears in dens could reduce or eliminate that probability. The purpose of this manual is to provide agency and private sector land managers with the information necessary to perform effective FLIR surveys to detect maternal dens. A list of personnel who can provide additional information is provided in Appendix 2.
Documenting the distribution of land-cover types on the Arctic National Wildlife Refuge coastal plain is the foundation for impact assessment and mitigation of potential oil exploration and development. Vegetation maps facilitate wildlife studies by allowing biologists to quantify the availability of important wildlife habitats, investigate the relationships between animal locations and the distribution or juxtaposition of habitat types, and assess or extrapolate habitat characteristics across regional areas. To meet the needs of refuge managers and biologists, satellite imagery was chosen as the most cost-effective method for mapping the large, remote landscape of the 1002 Area. Objectives of our study were the following: 1) evaluate a vegetation classification scheme for use in mapping. 2) determine optimal methods for producing a satellite-based vegetation map that adequately met the needs of the wildlife research and management objectives; 3) produce a digital vegetation map for the Arctic Refuge coastal plain using Lands at-Thematic Mapper(TM) satellite imagery, existing geobotanical classifications, ground data, and aerial photographs, and 4) perform an accuracy assessment of the map.
Documentation of the natural range of variation in ecological, life history, and physiological characteristics of caribou ( Rangifer tarandus ) of the Porcupine caribou herd is a necessary base for detecting or predicting any potential effects of industrial development on the performance (e.g., distribution, demography, weight-gain of individuals) of the herd. To demonstrate an effect of development, post-development performance must differ from pre-development performance while accounting for any natural environmental trends. We had 2 working hypotheses for our investigations: 1) performance of the Porcupine caribou herd was associated with environmental patterns and habitat quality, and 2) access to important habitats was a key influence on demography. We sought to document the range of natural variation in habitat conditions, herd size, demography (defined here as survival and reproduction), sources and magnitude of mortality, distribution, habitat use, and weight gain and loss, and to develop an understanding of the interactions among these characteristics of the herd. In addition, we investigated ways that we could use this background information, combined with auxiliary information from the adjacent Central Arctic caribou herd, to predict the direction and magnitude of any potential effects of industrial oil development in the 1002 Area of the Arctic National Wildlife Refuge on Porcupine caribou herd calf survival on the herd's calving grounds during June.
It is reported that in the spring of 1969 a high official of one of the oil companies was flying over the area of oil development in the vicinity of Prudhoe Bay. He is quoted as saying "If the American people could see what we are doing to their land here, they would want to abolish the use of the reciprocating engine." The last really large area of wilderness in the United States is the' Brooks Range and the Arctic Coastal Plain which stretches from that range to the Arctic Ocean. The proving of the exploratory oil wells which have been drilled on the coastal plain in the vicinity of Prudhoe Bay makes it virtually certain that this heretofore mostly unknown country will rapidly and vigorously be exposed to a variety of changes caused by the influx of men and their equipment. Even within the first four months of 1969 the whole aspect of the central part of the region has been importantly changed by the drilling programs of several large oil companies. So suddenly was this change brought about that no long-range plans have been developed either to soften the effect of such development on the natural environment or even to record the progress of these effects. Yet the absence of a plan provides an inadvertent potential advantage in that there has' been no history of increasingly firm Federal policy which, in other places, has often made it difficult to take newly conceived action in line with the increasing societal interest in environmental preservation. The lack of firm Federal policy provides here a unique opportunity for the application of new rules and investigative techniques aimed at minimizing the adverse effects on the environment while5.at the same time, not unduly hindering the development of the natural resources. But the speed with which the changes are being wrought makes it imperative that the principles applicable here to environmental protection or preservation, be enunciated immediately and that from these principles flow farsighted regulations which reflect the new interest in combining resource development with environmental protection. The present report constitutes a brief summary of the conditions existing in northern Alaska in the spring of 1969, presenting some inferences on the environmental changes which can be expected in the future and offering some specific steps which, if taken immediately and positively, could greatly ameliorate the adverse effects of rapid development in the absence of positive steps for environmental protection. In that regard, then, this report is ephemeral in character because the conditions in northern Alaska will surely change with great rapidity. Considering the"fragility and sensitivity of the ecosystems existing there, the changes can be both harsh and permanent. Therefore, whatever value lies in the recommendations made here., the results of their application will depend on the promptness of their consideration, amendment, and application. Whatever form the actions might take for minimizing the harm to the environment, the urgency of the matter can hardly be overestimated.
Alaska is part of an international circumpolar North, which makes the United States an Arctic nation. Alaska is a place of Indigenous ingenuity and adaptation, a place where environmental extremes challenge the ways of living. In its more recent history, Alaska has been a place of resources and influx-a land known best for what it provides. This frontier persona, with its sourdoughs and prospectors, has not been easily shed, but Alaska today is pivotal because it represents America's North and a complex and changing Arctic. North: Finding Place in Alaska explores the state's various facets through exhibitions and artifacts at the Anchorage Museum and the words of a diverse selection of writers, curators, historians, anthropologists, and artists. From romantic landscapes by Rockwell Kent and Thomas Hill, to the art and spirituality of Alaska's Native peoples represented by a bentwood feast dish and a uniquely carved hook for catching halibut, this collection examines connections throughout the circumpolar North. No longer as remote as once thought, Alaska serves as a narrative for our future.
Transport of a radioisotope in a sediment-water system can be retarded by sorption of the isotope to solid; which is controlled by the affinity of the radioisotope for the sediment particles. In order to study trace metal and ra- dionuclide mobility on the sea floor, the following measurements were carried out: (1)effective diffusion rates in sediments in the laboratory and on the sea floor, (2) laboratory distribution ratio (K d ) values, which measure the affinity of an element for the solid phase, and (3) field Kd values. Effective dffusion rates and Kd values for the radioisotopes 134 C s 125 Sb, 203 Hg, 133 Ba, 7 Be, 65 Z, 54 M, 60 Co, 59 Fe, and 113 Sn were measured for si= marine sediments: carbonate ooze, siliceous clay, red clay, metalliferous sediment, hemipelagic sediment, and terrigenous clay. The terrigenous clays analyzed are similar in composition and texture to sediments from sites of present and potential radioactive waste contamination in the arctic. Based on the effective diffusion coefficients (D s) determined in the laboratory, the isotope mobility fell into five groups. Diffusive transport rates fall into similar mobility groups for all sediment types tested both in the laboratory and on the sea floor. Interaction of the radionuclide with solids was the primary mechanism for reducing its mobility in the sediment-water system. As it is difficult to measure in situ diffusion rates directly, this suggests that K d values based on measured sediment properties can be used to help determine in situ diffusion rates for radioactive waste near the sediment-water interface for other locations, such as the Arctic. The relative contributions of diffusion, bioturbation, irrigation, and sediment transport to radionuclide transport can then be assessed and used to predict the interactions and fate of the radioactive waste in the sedimentary environment.
Interpretation of paleoclimate records requires an understanding of Earth’s climate system, the causes (forcings) of climate changes, and the processes that amplify (positive feedback) or damp (negative feedback) these changes. Paleoclimatologists reconstruct the history of climate from proxies, which are those characteristics of sedimentary deposits that preserve paleoclimate information. A great range of physical, chemical, isotopic, and biological characteristics of lake and ocean sediments, ice cores, cave formations, tree rings, the land surface itself, and more are used to reconstruct past climate. Ages of climate events are obtained by counting annual layers, measuring effects of the decay of radioactive atoms, assessing other changes that accumulate through time at rates that can be assessed accurately, and using time-markers to correlate sediments with others that have had their ages measured more accurately. Not all questions about the history of Earth’s climate can be answered through paleoclimatology: in some cases the necessary sediments are not preserved, or the climatic variable of interest is not recorded in the sediments. Nonetheless, many questions can be answered from the available information. An overview of the history of Arctic climate during the past 65 million years (m.y.) shows a long-term irregular cooling for tens of millions of years. As ice became established in the Arctic, it grew and shrank for tens of thousands of years in regular cycles. During at least the most recent of these cycles, shorter lived, large, and rapid fluctuations occurred, especially around the North Atlantic Ocean. The last 11,000 years or so have remained generally warm and relatively stable, but with small climate changes of varying spacing and size. Assessment of the causes of climate changes, and the records of those causes, shows that reduction in atmospheric carbon-dioxide concentration and changes in continental positions were important in the cooling trend throughout tens of millions of years. The cycling in ice extent was paced by features of Earth’s orbit and amplified by the effects of the ice itself, changes in carbon dioxide and other greenhouse gases, and additional feedbacks. Abrupt climate changes were linked to changes in the circulation of the ocean and the extent of sea ice. Changes in the Sun’s output and in Earth’s orbit, volcanic eruptions, and other factors have contributed to the natural climate changes since the end of the last ice age.
Freshwater ecosystems of the Alaskan Arctic and Subarctic provide resources that are culturally, ecologically, and economically invaluable. Presently, these regions are relatively free of the impacts from invasive species compared to southern latitudes. To date, there have been relatively few verified introductions of aquatic invasive species (AIS) to freshwater ecosystems in Alaska. The expanding list and distribution of AIS has led to significant negative ecological and economic impacts (e.g., waterweed Elodea nuttalli ; E. canadensis and northern pike Esox Lucius introduced outside its native range in Alaska). Escalating human activity across Alaskan lands and waters, coupled with rapidly shifting environmental conditions, increases the potential for new species introductions and subsequent establishment. Creating a proactive framework for well-informed decision-making and action can improve the effectiveness of prevention efforts and bolster decision support tools that help resource managers direct limited resources. Prioritizing AIS that may be introduced and become established, as well as the locations at highest risk of invasion, is foundational to building a proactive invasive species management framework in Alaska. This project sought to identify and prioritize AIS known to be invasive in the contiguous United States, evaluate current and future habitat suitability for AIS in Alaska, and assess potential for AIS to be transported to habitats across Alaska, utilizing similar assessment methods as implemented for Bering Sea marine invasive species and non-native plants in Alaska. To accomplish this goal, the objectives of the project were to: 1) develop a formal ranked list of potential AIS to freshwater systems of Alaska; 2) assess the level of establishment risk for potential AIS by developing habitat suitability models for waterbodies across Alaska; and 3), identify potential pathways and specific vectors for high-risk AIS to invade Alaska and develop a framework for how vector analysis will be completed to understand transport risk. Overall, our goal is horizon scanning which is defined by Roy et al. (2019) as “a systematic examination of potential threats and opportunities, within a given context, and likely future developments, which are at the margin of current thinking and planning.” The scans include pathway analyses and risk screening of species present at pathway origin points, with a focus on identifying species at high risk of being introduced, becoming established, spreading, and causing harm. We refined a list of 28 AIS from a list of hundreds based on characterizations of species’ invasiveness and species’ proximity to Alaska (USGS 2020; GBIF 2022). Next, we evaluated the relative invasiveness of individual species to create an initial AIS ranking. We sought to characterize habitat suitability of AIS by selecting variables that were continental in scale, covering North America to include Alaska as well as the lower 48 states comparing natural discharge, sub-basin average terrain slope (degrees), average silt fraction, average organic carbon, lithological class, and human footprint in sub-basin in 2009. We estimated AIS habitat suitability across the entire state of Alaska using the physiological tolerances of the AIS (Appendix 2). We also evaluated pathways and vectors for the introduction of AIS (Appendix 2). Many pathways and vectors considered did not meet the criteria for Alaska or freshwater systems. Of the 28 ranked species that we categorized as very high, high, and moderate levels of invasiveness; all three risk groups included fish and mollusks (Appendix 2). One commonality of the very high-invasiveness-ranked species was the availability of Ecological Risk Screening Summary documents (USFWS, 2022) produced by U.S. Fish and Wildlife Service (USFWS), except for the goldfish ( Carassius auratus ) and the New Zealand mudsnail ( Potamopyrgus antipodarum ). The Ecological Risk Screening Summary is now available for New Zealand mudsnails. In general, fish species often ranked very high or high in invasiveness and included sportfish and aquarium fish, suggesting the importance of pathways such as aquarium trade, fishing industry, intentional (but illegal) introductions of sportfishes and aquarium fishes for establishment. The technique we used for habitat suitability models necessitated aquatic environmental datasets that were continental in scale, which was often interpolated from very coarse resolution source data layers, particularly in Alaska. Better spatial data representing aquatic environments would likely improve this approach. While the lack of introductions in Alaska and nearby provinces and states is encouraging, the lack of occurrence data for the focal species also created complications for habitat suitability modeling. Despite the challenges, the habitat suitability models indicated limited suitability for warmwater species while some species, such as Brook trout (S alvelinus fontinalis ), have high habitat suitability across Alaska no matter what threshold approach is taken. Some environmental predictors were more important than others. Specifically, the most important predictor variable, ‘frost free days,’ was critical for 15 out of 28 species as expected due to harsh winter conditions in Arctic and Subarctic regions. The second most important predictor was ‘subbasin land surface runoff’, a variable that indicates the amount of discharge and runoff, while the third most important predictor was ‘snow cover’ another indication of winter conditions. Overall, the ability to understand the effect of future climate scenarios on the establishment of AIS was challenging. A detailed dataset of freshwater temperatures and water chemistry (e.g., pH, calcium) would greatly improve the ability to predict invasiveness of freshwater species to Alaska’s ecosystems on a regional basis. Future studies may benefit from a more focused geographic scope examining a group of subbasins or a regional basin rather than the entire state. These drainages could be selected based upon the mostly likely locations of introduction pathways. The two most prevalent pathway risks for AIS are in-state transfer and stowaways/contaminants. Although there are examples of introductions from other pathways, the risk is somewhat mitigated by Alaska’s climate and regulations. However, variable application of protocols for inspection and cleaning of fishing gear, watercraft, and other similar items while traveling into Alaska as well as transferring from waterbody to waterbody within the state creates a substantial risk in introducing invasive species. We plot cumulative invasive vulnerability for all subbasins and for the top 10% of subbasins (Appendix 3).
An analysis of variability in the winter mass balance (WMB) of 22 glaciers in the Northern Hemisphere indicates two primary modes of variability that explain 46% of the variability among all glaciers. The first mode of variability characterizes WMB variability in Northern and Central Europe and the second mode primarily represents WMB variability in northwestern North America, but also is related to variability in WMB of one glacier in Europe and one in Central Asia. These two modes of WMB variability are explained by variations in mesoscale atmospheric circulation which are driving forces of variations in surface temperature and precipitation. The first mode is highly correlated with the Arctic Oscillation Index, whereas the second mode is highly correlated with the Southern Oscillation Index. In addition, the second mode of WMB variability is highly correlated with variability in global winter temperatures. This result suggests some connection between global temperature trends and WMB for some glaciers.
Perennial snowfields are generally receding worldwide, though the precise mechanisms causing recessions are not always well understood. Here we apply a numerical snowpack model to identify the leading factors controlling the mass balance of two perennial snowfields that have significant human interest: Arapaho glacier, located at Niwot Ridge in the Colorado Rocky Mountains (United States), and a snowfield located in the Ulaan Taiga (Mongolia). The two locations were chosen because they differ in elevation, slope and aspect. However, both have sub-arctic climates and are located within semi-arid regions. We show that for these two locations the snowfield mass balance is primarily sensitive to air temperature and wind speed, followed by precipitation and dust deposition amounts. We find that the sensitivities are similar for the center of the snowfield as well as the margins.