Scaling-up permafrost thermal measurements in western Alaska using an ecotype approach

Permafrost temperatures are increasing in Alaska due to climate change and in some cases permafrost is thawing and degrading. In areas where degradation has already occurred the effects can be dramatic, resulting in changing ecosystems, carbon release, and damage to infrastructure. However, in many areas we lack baseline data, such as subsurface temperatures, needed to assess future changes and potential risk areas. Besides climate, the physical properties of the vegetation cover and subsurface material have a major influence on the thermal state of permafrost. These properties are often directly related to the type of ecosystem overlaying permafrost. In this paper we demonstrate that classifying the landscape into general ecotypes is an effective way to scale up permafrost thermal data collected from field monitoring sites. Additionally, we find that within some ecotypes the absence of a moss layer is indicative of the absence of near-surface permafrost. As a proof of concept, we used the ground temperature data collected from the field sites to recode an ecotype land cover map into a map of mean annual ground temperature ranges at 1 m depth based on analysis and clustering of observed thermal regimes. The map should be useful for decision making with respect to land use and understanding how the landscape might change under future climate scenarios

Landsat-based lake distribution and changes in western Alaska permafrost regions between the 1970s and 2010s

Lakes are an important ecosystem component and geomorphological agent in northern high latitudes and it is important to understand how lake initiation, expansion and drainage may change as high latitudes continue to warm. In this study, we utilized Landsat Multispectral Scanner System (MSS) images from the 1970s (1972, 1974, and 1975) and Operational Land Imager (OLI) images from the 2010s (2013, 2014, and 2015) to assess broad-scale distribution and changes of lakes larger than 1 ha across the four permafrost zones (continuous, discontinuous, sporadic, and isolated extent) in western Alaska. Across our ca 70,000 km2study area, we saw a decline in overall lake coverage across all permafrost zones with the exception of the sporadic permafrost zone. In the continuous permafrost zone lake area declined by -6.7 % (-65.3 km2), in the discontinuous permafrost zone by -1.6 % (-55.0 km2), in the isolated permafrost zone by -6.9 % (-31.5 km2) while lake cover increased by 2.7 % (117.2 km2) in the sporadic permafrost zone. Overall, we observed a net drainage of lakes larger than 10 ha in the study region. Partial drainage of these medium to large lakes created an increase in the area covered by small water bodies <10 ha, in the form of remnant lakes and ponds by 7.1 % (12.6 km2) in continuous permafrost, 2.5 % (15.5 km2) in discontinuous permafrost, 14.4 % (74.6 km2) in sporadic permafrost, and 10.4 % (17.2 km2) in isolated permafrost. In general, our observations indicate that lake expansion and drainage in western Alaska are occurring in parallel. As the climate continues to warm and permafrost continues to thaw, we expect an increase in the number of drainage events in this region leading to the formation of higher numbers of small remnant lakes

Circumpolar permafrost maps and geohazard indices for near-future infrastructure risk assessments

Ongoing climate change is causing fundamental changes in the Arctic, some of which can be hazardous to nature and human activity. In the context of Earth surface systems, warming climate may lead to rising ground temperatures and thaw of permafrost. This Data Descriptor presents circumpolar permafrost maps and geohazard indices depicting zones of varying potential for development of hazards related to near-surface permafrost degradation, such as ground subsidence. Statistical models were used to predict ground temperature and the thickness of the seasonally thawed (active) layer using geospatial data on environmental conditions at 30 arc-second resolution. These predictions, together with data on factors (ground ice content, soil grain size and slope gradient) affecting permafrost stability, were used to formulate geohazard indices. Using climate-forcing scenarios (Representative Concentration Pathways 2.6, 4.5 and 8.5), permafrost extent and hazard potential were projected for the 2041-2060 and 2061-2080 time periods. The resulting data (seven permafrost and 24 geohazard maps) are relevant to near-future infrastructure risk assessments and for targeting localized geohazard analyses.Peer reviewe

Food Storage in Permafrost and Seasonally Frozen Ground in Chukotka and Alaska Communities

Food cellars, otherwise referred to as ice or meat cellars, (lednik in Russian, k’aetyran in Chukchi, siġļuaq in Iñupiaq, and siqlugaq in Yupik) are a natural form of refrigeration in permafrost or seasonally frozen ground used to preserve, age, and ferment foods harvested for subsistence, including marine mammals, birds, fish, and plants. Indigenous peoples throughout the Arctic have constructed cellars in frozen ground for millennia. This paper focuses on cellars in Russian and American coastal and island communities of the Bering Strait, the region otherwise known as Beringia. This area has a unique, culturally rich, and politically dynamic history. Many traditions associated with cellars are threatened in Chukchi communities in Russia because of the impacts of climate change, relocation, dietary changes, and industrial development. However, even with warmer temperatures, cellars still provide a means to age and ferment food stuffs following traditional methods. In cooperation with local stakeholders, we measured internal temperatures of 18 cellars in 13 communities throughout the Bering Strait region and northern Alaska. Though cellars are widely used in permafrost regions, their structure, usage, and maintenance methods differ and exhibit influences of local climates, traditions, and economic activities. Monitoring internal temperatures and recording structural descriptions of cellars is important in the face of climate change to better understand the variety and resilience of living adaptations in different cold regions.Les caves à denrées, aussi connues sous le nom de caves à glace ou de caves à viande (lednik en russe, k’aetyran en tchouktche, siġļuaq en iñupiaq, et siqlugaq en yupik) constituent une forme de réfrigération naturelle dans le pergélisol ou dans le gélisol saisonnier permettant de conserver, de maturer et de fermenter les denrées récoltées à des fins de subsistance, dont les mammifères marins, les oiseaux, les poissons et les plantes. Cela fait des millénaires que les peuples autochtones de l’Arctique construisent des caves dans le gélisol. Cet article porte sur les caves se trouvant dans les localités côtières et insulaires russes et américaines du détroit de Béring, région qui porte également le nom de Béringie. L’histoire de cette région est unique, culturellement riche et politiquement dynamique. De nombreuses traditions liées aux caves des localités tchouktches de la Russie sont menacées en raison des incidences du changement climatique, de la délocalisation, du changement des régimes alimentaires et de l’expansion industrielle. Cependant, malgré les températures plus élevées, les caves constituent toujours un moyen de maturer et de fermenter les denrées alimentaires selon les méthodes traditionnelles. En collaboration avec les parties prenantes de la région, nous avons mesuré les températures internes de 18 caves situées dans 13 localités de la région du détroit de Béring et du nord de l’Alaska. Bien que les caves soient courantes dans les régions de pergélisol, leur structure, leur usage et les méthodes d’entretien diffèrent, et elles sont à l’image des influences des traditions, des activités économiques et des climats locaux. La surveillance des températures internes et l’enregistrement des descriptions structurales des caves revêtent de l’importance à la lumière du changement climatique, car elles permettent de mieux comprendre la variété et la résilience des adaptations de vie dans différentes régions froides.называемые иногда мясными ямами (лéдник по-русски, к’этыран по-чукотски, Siġļuaq или Siqlugaq по-эскимосски), обустроены как в вечномёрзлых породах, так и в сезонноталом слое и являются естественной формой заморозки для сохранения, выдержки и ферментации пищевых продуктов, добытых для пропитания: мясо морских млекопитающих, дичь, рыба, растения и др. Коренные жители Арктики обустраивали хранилища в мерзлоте на протяжении тысячелетий. Данная статья посвящена подземным хранилищам в российских и американских поселениях на берегах Берингова пролива – региона, также называемого Берингией. Эта территория имеет уникальную, богатую культурой и политически динамичную историю. Многие традиции, связанные с хранилищами в поселениях Чукотки, находятся под угрозой исчезновения из-за климатических изменений, миграции жителей, изменений в рационе и промышленного освоения территории. Однако даже при повышении температуры воздуха в хранилищах по-прежнему можно выдерживать и ферментировать пищу традиционными способами. При сотрудничестве с местным населением мы измерили температуры внутреннего воздуха в 18 лéдниках в 13 поселениях в регионе Берингова пролива и на севере Аляски. Несмотря на широкое использование таких хранилищ в криолитозоне, их структура, использование и методы обслуживания различаются под влиянием климатических условий, традиций и особенностей промысла. Мониторинг внутренней температуры воздуха в лéдниках и описание их конструкций важны в контексте изменения климата для лучшего понимания разнообразия и эффективности различных способов адаптации к жизни в холодных регионах

Climate Change Drives Widespread and Rapid Thermokarst Development in Very Cold Permafrost in the Canadian High Arctic

Climate warming in regions of ice‐rich permafrost can result in widespread thermokarst development, which reconfigures the landscape and damages infrastructure. We present multisite time series observations which couple ground temperature measurements with thermokarst development in a region of very cold permafrost. In the Canadian High Arctic between 2003 and 2016, a series of anomalously warm summers caused mean thawing indices to be 150–240% above the 1979–2000 normal resulting in up to 90 cm of subsidence over the 12‐year observation period. Our data illustrate that despite low mean annual ground temperatures, very cold permafrost (<−10 °C) with massive ground ice close to the surface is highly vulnerable to rapid permafrost degradation and thermokarst development. We suggest that this is due to little thermal buffering from soil organic layers and near‐surface vegetation, and the presence of near‐surface ground ice. Observed maximum thaw depths at our sites are already exceeding those projected to occur by 2090 under representative concentration pathway version 4.5

The Northern Eurasia Earth Science Partnership: An Example of Science Applied to Societal Needs

Northern Eurasia, the largest landmass in the northern extratropics, accounts for ~20% of the global land area. However, little is known about how the biogeochemical cycles, energy and water cycles, and human activities specific to this carbon-rich, cold region interact with global climate. A major concern is that changes in the distribution of land-based life, as well as its interactions with the environment, may lead to a self-reinforcing cycle of accelerated regional and global warming. With this as its motivation, the Northern Eurasian Earth Science Partnership Initiative (NEESPI) was formed in 2004 to better understand and quantify feedbacks between northern Eurasian and global climates. The first group of NEESPI projects has mostly focused on assembling regional databases, organizing improved environmental monitoring of the region, and studying individual environmental processes. That was a starting point to addressing emerging challenges in the region related to rapidly and simultaneously changing climate, environmental, and societal systems. More recently, the NEESPI research focus has been moving toward integrative studies, including the development of modeling capabilities to project the future state of climate, environment, and societies in the NEESPI domain. This effort will require a high level of integration of observation programs, process studies, and modeling across disciplines

Massive thermokarst lake area loss in continuous ice-rich permafrost of the northern Seward Peninsula, Northwestern Alaska, 1949-2015

Thermokarst lakes are important factors for permafrost landscape dynamics and carbon cycling. Thermokarst lake cover is especially high in Arctic lowlands with ice-rich permafrost. In most of these regions, multiple lake generations have been identified that overlap each other in space and time, giving rise to the hypothesis of thermokarst lake cycling and its association with complex cryostratigraphical conditions where multiple lacustrine and palustrine sequences may follow on top of each other and talik and carbon cycle histories are complicated. In northwestern Alaska on the northern Seward Peninsula, ice-rich permafrost lowlands have strongly been affected by thermokarst during the Holocene and up to six generations of lake basins overlap spatially (Jones et al., 2012). Modern thermokarst lakes are also abundant in this region and expand gradually by thermo-erosion along shores (Jones et al., 2011). We here report on the analysis of multi-temporal remote sensing data for a 12,200 km2 lowland area in the relatively warm continuous permafrost zone of the northern Seward Peninsula, demonstrating that thermokarst lake drainage in this region was occurring on a massive scale from 1949-2015. Contrary to most previous studies that suggest an increase in thermokarst lake area in continuous permafrost, we observed a significant net decrease in thermokarst lake area largely due to catastrophic lake drainage. Lateral lake expansion by thermo-erosion continued but did not offset the net area loss. Climate data analysis revealed a potential correlation with increased winter precipitation that may have resulted in a combination of high lake water levels, increased spring runoff with higher potential for drainage channel formation, and near-surface permafrost degradation, ultimately enhancing lake drainage. The observed magnitude of lake drainage implicates strong and lasting impacts on regional hydrology, biogeochemical cycling, surface energy budgets, state of the permafrost, ecosystem character, waterfowl and fish habitats, and subsistence lifestyles in the study region, portions of which belong to the Bering Land Bridge National Preserve. The datasets used in this analysis include a wide range of remote sensing images and topographic data available for this region, such as aerial photography, historic topographic maps, high resolution satellite images (Corona, Spot, Ikonos, Quickbird, Worldview, GeoEye), and the full Landsat archive. Field studies included reconnaissance flights targeting freshly drained lakes and ground based data collection such as lake basin coring. Our findings suggest that a significant portion of lakes in this region has drained over the last decades and that in particular large lakes are vulnerable to disappearance. Initial analyses of relationships of lake drainages with permafrost distribution in the region suggest positive correlations between lake loss and permafrost degradation in much of the region. Our findings highlight that permafrost and lake-rich landscapes in Alaska are already changing rapidly and permanently in a warming world. This set of studies was supported by funding from NASA Carbon Cycle Sciences, NSF Arctic System Sciences, the European Research Council, and the Western Alaska Landscape Conservation Cooperative. References: Jones B, Grosse G, Arp CD, Jones MC, Walter Anthony KM, Romanovsky VE (2011): Modern thermokarst lake dynamics in the continuous permafrost zone, northern Seward Peninsula, Alaska. Journal of Geophysical Research – Biogeosciences, 116, G00M03. Jones MC, Grosse G, Jones BM, Walter Anthony KM (2012): Peat accumulation in a thermokarstaffected landscape in continuous ice-rich permafrost, Seward Peninsula, Alaska. Journal of Geophysical Research – Biogeosciences, 117, G00M07

Deep Yedoma permafrost: A synthesis of depositional characteristics and carbon vulnerability

Permafrost is a distinct feature of the terrestrial Arctic and is vulnerable to climate warming. Permafrost degrades in different ways, including deepening of a seasonally unfrozen surface and localized but rapid development of deep thaw features. Pleistocene ice-rich permafrost with syngenetic ice-wedges, termed Yedoma deposits, are widespread in Siberia, Alaska, and Yukon, Canada and may be especially prone to rapid-thaw processes. Freeze-locked organic matter in such deposits can be re-mobilized on short time-scales and contribute to a carbon cycle climate feedback. Here we synthesize the characteristics and vulnerability of Yedoma deposits by synthesizing studies on the Yedoma origin and the associated organic carbon pool. We suggest that Yedoma deposits accumulated under periglacial weathering, transport, and deposition dynamics in non-glaciated regions during the late Pleistocene until the beginning of late glacial warming. The deposits formed due to a combination of aeolian, colluvial, nival, and alluvial deposition and simultaneous ground ice accumulation. We found up to 130 gigatons organic carbon in Yedoma, parts of which are well-preserved and available for fast decomposition after thaw. Based on incubation experiments, up to 10% of the Yedoma carbon is considered especially decomposable and may be released upon thaw. The substantial amount of ground ice in Yedoma makes it highly vulnerable to disturbances such as thermokarst and thermo-erosion processes. Mobilization of permafrost carbon is expected to increase under future climate warming. Our synthesis results underline the need of accounting for Yedoma carbon stocks in next generation Earth-System-Models for a more complete representation of the permafrost-carbon feedback

Consequences of permafrost degradation for Arctic infrastructure - Bridging the model gap between regional and engineering scales

Infrastructure built on perennially frozen ice-rich ground relies heavily on thermally stable subsurface conditions. Climate-warming-induced deepening of ground thaw puts such infrastructure at risk of failure. For better assessing the risk of large-scale future damage to Arctic infrastructure, improved strategies for model-based approaches are urgently needed. We used the laterally coupled 1D heat conduction model CryoGrid3 to simulate permafrost degradation affected by linear infrastructure. We present a case study of a gravel road built on continuous permafrost (Dalton highway, Alaska) and forced our model under historical and strong future warming conditions (following the RCP8.5 scenario). As expected, the presence of a gravel road in the model leads to higher net heat flux entering the ground compared to a reference run without infrastructure and thus a higher rate of thaw. Further, our results suggest that road failure is likely a consequence of lateral destabilisation due to talik formation in the ground beside the road rather than a direct consequence of a top-down thawing and deepening of the active layer below the road centre. In line with previous studies, we identify enhanced snow accumulation and ponding (both a consequence of infrastructure presence) as key factors for increased soil temperatures and road degradation. Using differing horizontal model resolutions we show that it is possible to capture these key factors and their impact on thawing dynamics with a low number of lateral model units, underlining the potential of our model approach for use in pan-Arctic risk assessments. Our results suggest a general two-phase behaviour of permafrost degradation: an initial phase of slow and gradual thaw, followed by a strong increase in thawing rates after the exceedance of a critical ground warming. The timing of this transition and the magnitude of thaw rate acceleration differ strongly between undisturbed tundra and infrastructure-affected permafrost ground. Our model results suggest that current model-based approaches which do not explicitly take into account infrastructure in their designs are likely to strongly underestimate the timing of future Arctic infrastructure failure. By using a laterally coupled 1D model to simulate linear infrastructure, we infer results in line with outcomes from more complex 2D and 3D models, but our model's computational efficiency allows us to account for long-term climate change impacts on infrastructure from permafrost degradation. Our model simulations underline that it is crucial to consider climate warming when planning and constructing infrastructure on permafrost as a transition from a stable to a highly unstable state can well occur within the service lifetime (about 30 years) of such a construction. Such a transition can even be triggered in the coming decade by climate change for infrastructure built on high northern latitude continuous permafrost that displays cold and relatively stable conditions today.publishedVersio