In the past several decades, the use of all-terrain vehicles (ATVs) has proliferated in many Arctic communities in North America. One example is the village of Barrow, Alaska. This coastal community has only local roads, so all access to the interior utilizes off-road machines. These 4-wheel vehicles are the primary means of tundra traverse and transport in summer by hunters and berry-pickers, and by village residents accessing summer camps. Traveling cross-country is difficult due to the large number of thermokarst lakes, wetlands, and streams, and tundra trails tend to follow dryer higher ground while avoiding areas of high microrelief such as high-centered ice-wedge polygons. Thus, modern ATV trails tend to follow the margins of drained or partially drained thermokarst lake basins where it is flat and relatively dry, and these trails are heavily used. The deeply-ribbed tires of the heavy and powerful ATVs cause damage by destroying the vegetation and disturbing the underlying organic soil. Exposure of the dark soil enhances summer thaw and leads to local thermokarst of the ice-rich upper permafrost. The damage increases over time as vehicles continue to follow the same track, and sections eventually become unusable; this is especially true where the trail crosses ice-wedge troughs. Deep subsidence in the ponded troughs results in ATV users veering to avoid the wettest area, which leads to a widening of the damaged area. Helicopter surveys, site visits, and collection of ground penetrating radar data were combined with time series analysis of high-resolution aerial and satellite imagery for the period 1955–2014. The analysis reveals that there are 507km of off-road trails on the Barrow Peninsula. About 50% of the total trail length was developed before 1955 in association with resource extraction, and an additional 40% were formed between 1979 and 2005 by ATVs. Segments of the more modern trail are up to 100m wide. Damage to the tundra is especially pronounced in wet areas, such as ice-wedge troughs. Knowledgeable indigenous people are aware of the problem. Some remediation has been attempted by using heavy-duty PVC matting in areas of greatest damage, but this approach is prohibitively expensive on a large scale.

Since 2012, the physical and biogeochemical properties of ~60 lakes in northern Alaska have been investigated under CALON, a project to document landscape-scale variability of Arctic lakes in permafrost terrain. The network has ten nodes along two latitudinal transects extending inland 200 km from the Arctic Ocean. A meteorological station is deployed at each node and six representative lakes instrumented and continuously monitored, with winter and summer visits for synoptic assessment of lake conditions. Over the 4-year period, winter and summer climatology varied to create a rich range of lake responses over a short period. For example, winter 2012-13 was very cold with a thin snowpack producing thick ice across the region. Subsequent years had relatively warm winters, yet regionally variable snow resulted in differing gradients of ice thickness. Ice-out timing was unusually late in 2014 and unusually early in 2015. Lakes are typically well–mixed and largely isothermal, with minor thermal stratification occurring in deeper lakes during calm, sunny periods in summer. Lake water temperature records and morphometric data were used to estimate the ground thermal condition beneath 28 lakes. Application of a thermal equilibrium steady-state model suggests a talik penetrating the permafrost under many larger lakes, but lake geochemical data do not indicate a significant contribution of subpermafrost groundwater. Biogeochemical data reveal distinct spatial and seasonal variability in chlorophyll biomass, chromophoric dissolved organic carbon (CDOM), and major cations/anions. Generally, waters sampled beneath ice in April had distinctly higher concentrations of inorganic solutes and methane compared with August. Chlorophyll concentrations and CDOM absorption were higher in April, suggesting significant biological/biogeochemical activity under lake ice. Lakes are a positive source of methane in summer, and some also emit nitrous oxide and carbon dioxide. As part of the Indigenous Knowledge component,76 Inupiat elders, hunters and berry pickers have been interviewed and over 75 hours of videotaped interviews produced. The video library and searchable interview logs are archived with the North Slope community. All field data is archived at ACADIS, and further information is at www.arcticlakes.org.

Climate warming in the Arctic may result in release of carbon dioxide and/or methane from thawing permafrost soils, resulting in a positive feedback to warming. Permafrost thaw may also result in release of methane from previously trapped natural gas. The Arctic landscape is approximately 50% covered by shallow permafrost lakes, and these environments may serve as bellwethers for climate change – carbon cycle feedbacks, since permafrost thaw is generally deeper under lakes than tundra soils. Since 2011, the Circum-Arctic Lakes Observation Network (CALON) project has documented landscape-scale variability in physical and biogeochemical processes of Arctic lakes in permafrost terrain, including carbon cycle feedbacks to climate warming. Here we present a dataset of concentrations, isotope ratios (13C and 2H), and atmospheric fluxes of methane from lakes in Arctic Alaska. Concentrations of methane in lake water ranged from 0.3 to 43 micrograms per liter, or between 6 and 750 times supersaturated with respect to air. Isotopic measurements of dissolved methane indicated that most of the lakes had methane derived from anaerobic organic matter decomposition, but that some lakes may have a small source of methane from fossil fuel sources such as natural gas or coal beds. Concurrent measurements of methane fluxes and dissolved methane concentrations in summer of 2014 will aid in translating routine dissolved measurements into fluxes, and will also elucidate the relative importance of diffusive versus ebulliative fluxes. It is essential that measurements of methane emissions from Arctic lakes be continued long-term to determine whether methane emissions are on the rise, and whether warming of the lakes leads to increased venting of fossil fuel methane from enhanced thaw of permafrost beneath the lakes.

Although data for temporal spring river ice breakup are available for a number of Arctic rivers, there is a paucity of information related to the type of breakup.The Arctic Climate Impact Assessment (ACIA) of 2005 predicted a transition from mechanical to thermal spring breakup of ice cover on arctic rivers, with this shift being greatest in exclusively Arctic watersheds where observed warming is most pronounced.We describe a rare instance of an entirely Arctic river with limited but well documented historical and recent data regarding the type of breakup.Time-series ground imagery of spring breakup from 1966, 1975, 1978, 2009, 2010 and 2012, in combination with interviews of local inhabitants, documents a shift from predominantly mechanical to predominantly thermal breakup after spring 1978 and by spring 2009 within the context of a locally and regionally warming Arctic.The resultant shift from predominantly mechanical to predominantly thermal breakup is predicted to result in significant changes to water, sediment, nutrient and organic carbon fluxes, as well as riparian ecology and human activities.

Since 2003 our research team has been interviewing Inupiat elders and incorporating their indigenous knowledge (IK) about the environment into a specially designed Geographic Information System (GIS). We present a synthesis of the climate and landscape change information shared during the IK GIS project. We also summarize observations, which are not geographically specific and thus not expressible as GIS data points. We present several analyses of our dataset to date. These include a frequency analysis of the topically classified geocoded observations based on elder interviews, a summary of the geographic distribution of those observations, and a discussion of non-georeferenced observations. We identify several themes that IK holders and elders felt were crucial to record and discuss. Many of these observations include environmental, cultural, and historical knowledge, and reflect the perception that their world has substantially changed in the course of their lifetimes.

ABSTRACTDetailed bathymetric data were collected for 28 thermokarst lakes across the Arctic Coastal Plain (ACP) of northern Alaska from areas with distinctly different surficial sediments and topography. Lakes found in the low‐relief coastal area have developed in marine silts that are ice‐rich in the upper 6–10 m. The lakes tend to be shallow (~ 2 m), of uniform depth and lack prominent littoral shelves. Further inland on the ACP, lakes have formed in relatively ice‐poor aeolian sand deposits. In this hilly terrain, average lake depth is less (~ 1 m) despite deeper (3–5 m) central pools. This bathymetry reflects the influence of broad, shallow littoral shelves where sand, eroded from bluffs at the lake margin, is deposited concurrently with deep penetration of the talik beneath the basin centre. Lakes in the ACP‐Arctic Foothills transition zone to the south have developed in loess uplands. These yedoma deposits are extremely ice‐rich, and residual lakes found inside old lake basins (alases) are generally 2–4 m deep, reflecting continued talik development and ground subsidence following drainage of the original lake. However, where the expanding lake encroaches on the flanks of the upland at actively eroding bluffs, near‐shore pools develop that can be 6–9 m deep. It appears that thawing of ice‐rich permafrost during lake expansion causes ground subsidence and formation of deep pools above ablating ice wedges. These data suggest that thermokarst lake morphometry largely depends on the characteristics of the substrate beneath the lake and the availability of sediments eroded at the lake margin. Copyright © 2012 John Wiley & Sons, Ltd.

A traditional knowledge Inupiaq Web GIS, based on a five-year study and containing observations and environmental knowledge of Inupiat communities indigenous to Arctic Alaska, was incorporated into a Web-based platform. The website, Arctic Cultural Cartography, was created to be an open portal through which the password-protected Inupiaq Web GIS could be accessed. We discuss the process of developing the web GIS including the incorporation of user-friendly features such as links to interactive maps, video clips of interviews, discussion boards, and the integration of popular web interfaces such as Facebook. We also discuss short-and long-term goals for the further development of the GIS, its potential as a sustainable, participatory online database for sharing pertinent ecological knowledge, and challenges in achieving optimal community involvement given constraints imposed by remote locations with limited bandwidth.

ABSTRACTIn summer 2010, water temperature profile measurements were made in 12 thermokarst lakes along a 150‐km long north–south transect across the Arctic Coastal Plain of northern Alaska. In shallow lakes, gradual warming of the water column to 1–4°C begins at the lake bed during decay of the ice cover in spring. Rapid warming follows ice‐off, with water temperature responding synchronously to synoptic weather variations across the area. Regionally, ice‐off occurs 2–4 weeks later on lakes near the coast. Inland lakes are warmer (13°C) in mid‐summer than those near the coast (7°C), reflecting the regional climate gradient and the maritime effect. All lakes are well mixed and largely isothermal, with some thermal stratification (< 2°C) occurring during calm, sunny periods in deeper lakes. In deep (6–9 m) lake‐bed depressions that are likely ice‐wedge troughs, water cools by conduction to the colder sediments below, while concurrent warming occurs in the upper water column. A spatially dense sample of near‐surface temperature measurements was collected from one lake over a short period and shows warmer (2–3°C) temperatures on the upwind, sheltered end of the lake. This study demonstrates that climatic gradients, meteorological conditions and basin characteristics impact lake temperature dynamics. Copyright © 2012 John Wiley & Sons, Ltd.

New palynological and sedimentological data from St. Lawrence Island present a rare view into late-glacial and Holocene environments of the central Bering Land Bridge. The late glaciation was a time of dynamic landscape changes in south-central Beringia, with active thermokarst processes, including the formation and drainage of thaw lakes. The presence of such a wet, unstable substrate, if widespread, probably would have had an adverse impact on food sources and mobility for many of the large mammal populations. The establishment of Betula shrub tundra on the island suggests late-glacial summers that were warmer than present, consistent with regional paleoclimatic interpretations. However, the increasing proximity to the Bering Sea, as postglacial sea levels rose, modified the intensity of warming and prevented the establishment of deciduous forest as found in other areas of Beringia at this time. The mid- to late Holocene is marked by more stable land surfaces and development of Sphagnum and Cyperaceae peat deposits. The accumulation of organic deposits, decline of shrub Betula, and decrease in thermokarst disturbance suggest that conditions were cooler than the previous. A recent decline in peat accumulation at the study sites may relate to local geomorphology, but similar decreases have been noted for other arctic regions.

Ice formation and breakup on Arctic rivers strongly influence river flow, sedimentation, river ecology, winter travel, and subsistence fishing and hunting by Alaskan Natives. We use time-series ground imagery of the Meade River to examine the process at high temporal and spatial resolution. Freezeup from complete liquid cover to complete ice cover of the Meade River at Atqasuk, Alaska in the fall of 2008 occurred in less than three days between 28 September and 2 October 2008. Breakup in 2009 occurred in less than two hours between 23: 47 UTC on 23 May 2009 and 01: 27 UTC on 24 May 2009. All times in UTC. Breakup in 2009 and 2010 was of the thermal style in contrast to the mechanical style observed in 1966 and is consistent with a warming Arctic.

Indigenous knowledge is a valuable but under-used source of information relevant to landscape change research. We interviewed Inupiat elders, hunters, and other knowledge-holders in the villages of Barrow and Atqasuk on the western Arctic Coastal Plain of northern Alaska to gain further insight into the processes governing the ubiquitous lakes and the dynamics of landscape change in this region of continuous permafrost. The interviews provided a suite of information related to lakes and associated drained lake basins, as well as knowledge on landforms, environmental change, human events, and other phenomena. We were able to corroborate many observations independently and verify the timing of several large and significant lake drainage events using either aerial photography or remotely sensed time series. Data collected have been incorporated into a geodatabase to develop a multi-layer Geographic Information System that will be useful for local and scientific communities. This research demonstrates that indigenous knowledge can reveal a new understanding of landscape changes on the Arctic Coastal Plain in general and on lake processes in particular. We advocate ongoing, community-oriented research throughout the Arctic as a means of assessing and responding to the consequences of rapid environmental change.

This study presents modern erosion rate measurements based upon vertical aerial photography captured in 1955, 1979, and 2002 for a 100 km segment of the Beaufort Sea coastline. Annual erosion rates from 1955 to 2002 averaged 5.6 m a-1. However, mean erosion rates increased from 5.0 m a-1 in 1955–79 to 6.2 m a-1 in 1979–2002. Furthermore, from the first period to the second, erosion rates increased at 60% (598) of the 992 sites analyzed, decreased at 31% (307), and changed less than ± 30 cm at 9% (87). Historical observations and quantitative studies over the past 175 years allowed us to place our erosion rate measurements into a longer-term context. Several of the coastal features along this stretch of coastline received Western place names during the Dease and Simpson expedition in 1837, and the majority of those features had been lost by the early 1900s as a result of coastline erosion, suggesting that erosion has been active over at least the historical record. Incorporation of historical and modern observations also allowed us to detect the loss of both cultural and historical sites and modern infrastructure. U.S. Geological Survey topographic maps reveal a number of known cultural and historical sites, as well as sites with modern infrastructure constructed as recently as the 1950s, that had disappeared by the early 2000s as a result of coastal erosion. We were also able to identify sites that are currently being threatened by an encroaching coastline. Our modern erosion rate measurements can potentially be used to predict when a historical site or modern infrastructure will be affected if such erosion rates persist.

In this article we discuss an ongoing research project that links the knowledge and experience of Inupiat Eskimo elders, hunters, and berry harvesters with scientific observations and methods, to better understand environmental change on the Arctic Coastal Plain.[2] Quantitative scientific questions about climate-related changes to the Alaskan tundra are at the heart of our study, but this is also an interview-intensive interdisciplinary project that utilizes mixed methods and generates a range of secondary findings. Our primary goal here is to provide a preliminary presentation of some of the important qualitative data that has emerged from our interviews with Inupiat participants concerning climate change, subsistence, community values, and women's roles. We also provide detail on the background, methods, and objectives of our research, to help readers better understand the situation in northern Alaska, and to present our methodology for assessment by a multidisciplinary and multicultural audience.

Pollen records from Wonder and Ten Mile lakes, located at aititudinal treeline to the north and south of the Alaska Range respectively, document the vegetation history of a portion of the southern Alaskan boreal forest. The new pollen diagrams indicate a Betula shrub tundra, preceded at Wonder Lake by a sparse herb tundra, which characterized these two areas during latest Wisconsinan times. Populus was in the vicinity of Ten Mile Lake ca. 10,000 BP, but was apparently absent from Wonder Lake. Picea glauca grew at or near Ten Mile Lake by 9100 BP, with P. mariana becoming important ca. 7000 BP. The first forests at Wonder Lake were also dominated by P. glauca and followed by increased numbers of P. mariana. The timing of forest establishment at Wonder Lake is uncertain due to problematic radiocarbon dates. Alnus appears to be common in both regions by ca. 7000 BP. These records suggest that paleo-vegetational reconstructions are more difficult for the southern than northern boreal forests in Alaska because of greater topographic diversity, difficulties with over-representation of some pollen taxa, and problems with radiocarbon dating. Despite these concerns, available data from south-central Alaska suggest that southern and northern forests differ in their vegetational histories. Such differences, when related to temperature fluctuations that have been postulated for the Holocene, imply that the Alaskan boreal forest may not respond uniformly to future global warming.

A Delay-Tolerant Network (DTN) is a necessity for communication nodes that may need to wait for long periods to form networks. The IETF Delay Tolerant Network Research Group is developing protocols to enable such networks for a broad variety of Earth and interplanetary applications. The Arctic would benefit from a predictive velocity-enabled version of DTN that would facilitate communications between sparse, ephemeral, often mobile and extremely power-limited nodes. We propose to augment DTN with power-aware, buffer-aware location- and time-based predictive routing for ad-hoc meshes to create networks that are inherently location and time (velocity) aware at the network level to support climate research, emergency services and rural education in the Arctic. On Earth, the primary source of location and universal time information for networks is the Global Positioning System (GPS). We refer to this Arctic velocity-enabled Delay-Tolerant Network protocol as "GPSDTN" accordingly. This paper describes our requirements analysis and general implementation strategy for GPSDTN to support Arctic research and sustainability efforts.

Thousands of lakes are found on the Arctic Coastal Plain of northern Alaska and northwestern Canada. Developed atop continuous permafrost, these thaw lakes and associated drained thaw lake basins are the dominant landscape elements and together cover 46% of the 34,570 km2 western Arctic Coastal Plain (WACP). Lakes drain by a variety of episodic processes, including coastal erosion, stream meandering, and headward erosion, bank overtopping, and lake coalescence. Comparison of Landsat multispectral scanner (MSS) imagery from the mid‐1970s to Landsat 7 enhanced thematic mapper (ETM+) imagery from around 2000 shows that 50 lakes completely or partially drained over the approximately 25 year period, indicating landscape stability. The lake‐specific drainage mechanism can be inferred in some cases and is partially dependant on geographic settings conducive to active erosion such as riparian and coastal zones. In many cases, however, the cause of drainage is unknown. The availability of high‐resolution aerial photographs for the Barrow Peninsula extends the record back to circa 1950; mapping spatial time series illustrates the dynamic nature of lake expansion, coalescence, and drainage. Analysis of these historical images suggests that humans have intentionally or inadvertently triggered lake drainage near the village of Barrow. Efforts to understand landscape processes and identify events have been enhanced by interviewing Iñupiaq elders and others practicing traditional subsistence lifestyles. They can often identify the year and process by which individual lakes drained, thereby providing greater dating precision and accuracy in assessing the causal mechanism. Indigenous knowledge has provided insights into events, landforms, and processes not previously identified or considered.

The dominant landscape process on the Arctic Coastal Plain of northern Alaska is the formation and drainage of thaw lakes. Lakes and drained thaw-lake basins account for approximately 75% of the modern surface expression of the Barrow Peninsula. The thaw-lake cycle usually obliterates lacustrine or peat sediments from previous cycles, which could otherwise be used for paleoecological reconstruction of long-term landscape and vegetation changes. Several possible erosional remnants of a former topographic surface that predates the formation of the thaw lakes have been tentatively identified. These remnants are characterized by a higher elevation, a thick organic layer with very high ground ice content in the upper permafrost and a plant community somewhat atypical of the region. Ten soil cores were collected from one site, and one core was intensively sampled for soil organic carbon content, pollen analysis and 14C dating. The lowest level of the organic sediments represents the earliest phase of plant growth and dates to ca. 9000 cal BP. Palynological evidence indicates the presence of mesic shrub tundra (including sedge, birch, willow and heath vegetation), and microfossil indicators point to wetter eutrophic conditions during this period. Carbon accumulation was rapid due to high net primary productivity in a relatively nutrient-rich environment. These results are interpreted as the local response to ameliorating climate during the early Holocene. The middle Holocene portion of the record contains an unconformity, indicating that between 8200 and 4200 cal BP sediments were eroded from the site, presumably in response to wind activity during a drier period centered around 4500 cal BP. The modern vegetation community of the erosional remnant was established after 4200 cal BP and peat growth resumed. During the late Holocene, carbon accumulation rates (CARs) were greatly reduced in response to the combined effects of declining productivity associated with climatic cooling, and increased nutrient stress as paludification and permafrost aggradation sequestered mineral nutrients.

The purpose of this research was to map thaw lakes and drained thaw lake basins (DTLBs) on the North Slope of Alaska using satellite remote sensing. This research is the first to map DTLBs on a large scale for Alaska's Arctic Coastal Plain. Thaw lakes and DTLBs were classified from seven Landsat-7 scenes using texture analysis, spectral transformations, and image segmentation. The overall classification accuracy was 97.7% with a Kappa coefficient of 0.96. Thaw lakes had a producer accuracy of 99.1% and a user accuracy of 98.6%, while DTLBs had a producer accuracy of 93.8% and user accuracy of 98.1%. A total of 7054 km2 of thaw lakes were mapped, accounting for 20.4% of the Arctic Coastal Plain; there were 8917 km2 of DTLBs covering 25.7% of the study area. Continued research in the analysis of thaw lakes and DTLBs is crucial to our understanding of the global carbon cycle, atmospheric methane concentrations, heat flow and climate change.