Search for: All records

Abstract The Yukon‐Kuskokwim Delta has the largest intertidal wetland in North America, is a globally critical breeding area for waterbirds, and is home to the largest regional indigenous population in the Arctic. Here, coastal tundra ecosystems, wildlife, and indigenous communities are highly vulnerable to sea‐ice loss in the Bering Sea, sea‐level rise, storm flooding, erosion, and collapsing ground from permafrost thaw caused by climate warming. These drivers interact in non‐linear ways to increase flooding, salinization, and sedimentation, and thus, alter ecosystem trajectories and broader landscape evolution. Rapid changes in these factors over decadal time scales are highly likely to cause transformative shifts in coastal ecosystems across roughly 70% of the outer delta this century. We project saline and brackish ecotypes on the active delta floodplain with frequent sedimentation will maintain dynamic equilibrium with sea‐level rise and flooding, slightly brackish ecotypes on the inactive floodplain with infrequent flooding and low sedimentation rates will be vulnerable to increased flooding and likely transition to more saline and brackish ecotypes, and fresh lacustrine and lowland ecotypes on the abandoned floodplain with permafrost plateaus will be vulnerable to thermokarst, salinization and flooding that will shift them toward brackish ecosystems. This will greatly affect bird nesting and foraging habitats, with both winners and losers. Already, some Yup'ik communities are facing relocation of their low‐lying villages. The societal challenges and consequences of adapting to these changing landscapes are enormous and will require a huge societal effort. 

Abstract Accelerated climate warming has caused the majority of marine-terminating glaciers in the Northern Hemisphere to retreat substantially during the twenty-first century. While glacier retreat and changes in mass balance are widely studied on a global scale, the impacts of deglaciation on adjacent coastal geomorphology are often overlooked and therefore poorly understood. Here we examine changes in proglacial zones of marine-terminating glaciers across the Northern Hemisphere to quantify the length of new coastline that has been exposed by glacial retreat between 2000 and 2020. We identified a total of 2,466 ± 0.8 km (123 km a⁻¹) of new coastline with most (66%) of the total length occurring in Greenland. These young paraglacial coastlines are highly dynamic, exhibiting high sediment fluxes and rapidly evolving landforms. Retreating glaciers and associated newly exposed coastline can have important impacts on local ecosystems and Arctic communities. 

ABSTRACT The Yukon‐Kuskokwim Delta (YKD), covering ~75,000 km²of Alaska's discontinuous permafrost zone, has a historic (1902–2023) mean annual air temperature of ~−1°C and was previously thought to lack ice wedge networks. However, our recent investigations near Bethel, Alaska, revealed numerous near‐surface ice wedges. Using 20 cm resolution aerial orthoimagery from 2018, we identified ~50 linear km of ice wedge troughs in a 60 km²study area. Fieldwork in 2023 and 2024 confirmed ice wedges up to ~1.5 m wide and ~2.5 m in vertical extent, situated on average 0.9 m below the tundra surface (n = 29). Ground‐penetrating radar (GPR) detected additional ice wedges beyond those visible in the remote sensing imagery, suggesting an underestimation of their true abundance. Coring of polygonal centers revealed late‐Quaternary deposits, including thick early Holocene peat, late‐Pleistocene ice‐rich silts (reworked Yedoma), charcoal layers from tundra fires, and the Aniakchak CFE II tephra (~3600 cal yrs BP). Stable water isotopes from Bethel's wedge ice (mean δ¹⁸O = −15.7 ‰, δ²H = −113.1 ‰) indicate a relatively enriched signature compared to other Holocene ice wedges in Alaska, likely due to warmer temperatures and maritime influences. Expanding our mapping across the YKD using high‐resolution satellite imagery from 2012 to 2024, we estimate that the Holocene ice wedge zone encompasses ~30% of the YKD tundra region. Our findings demonstrate that ice wedge networks are more widespread across the YKD than previously recognized, emphasizing both the resilience and vulnerability of the region's warm, ice‐rich permafrost. These insights are crucial for understanding permafrost responses to climate change and assessing agricultural potential and development in the region. 

ABSTRACT Research in geocryology is currently principally concerned with the effects of climate change on permafrost terrain. The motivations for most of the research are (1) quantification of the anticipated net emissions of CO₂and CH₄from warming and thaw of near‐surface permafrost and (2) mitigation of effects on infrastructure of such warming and thaw. Some of the effects, such as increases in ground temperature or active‐layer thickness, have been observed for several decades. Landforms that are sensitive to creep deformation are moving more quickly as a result, andRock Glacier Velocityis now part of the Essential Climate VariablePermafrostof the Global Climate Observing System. Other effects, for example, the occurrence of physical disturbances associated with thawing permafrost, particularly the development of thaw slumps, have noticeably increased since 2010. Still, others, such as erosion of sedimentary permafrost coasts, have accelerated. Geochemical effects in groundwater from trace elements, including contaminants, and those that issue from the release of sediment particles during mass wasting have become evident since 2020. Net release of CO₂and CH₄from thawing permafrost is anticipated within two decades and, worldwide, may reach emissions that are equivalent to a large industrial economy. The most immediate local concerns are for waste disposal pits that were constructed on the premise that permafrost would be an effective and permanent containment medium. This assumption is no longer valid at many contaminated sites. The role of ground ice in conditioning responses to changes in the thermal or hydrological regimes of permafrost has re‐emphasized the importance of regional conditions, particularly landscape history, when applying research results to practical problems. 

Abstract Arctic coastal environments are eroding and rapidly changing. A lack of pan-Arctic observations limits our ability to understand controls on coastal erosion rates across the entire Arctic region. Here, we capitalize on an abundance of geospatial and remotely sensed data, in addition to model output, from the North Slope of Alaska to identify relationships between historical erosion rates and landscape characteristics to guide future modeling and observational efforts across the Arctic. Using existing datasets from the Alaska Beaufort Sea coast and a hierarchical clustering algorithm, we developed a set of 16 coastal typologies that captures the defining characteristics of environments susceptible to coastal erosion. Relationships between landscape characteristics and historical erosion rates show that no single variable alone is a good predictor of erosion rates. Variability in erosion rate decreases with increasing coastal elevation, but erosion rate magnitudes are highest for intermediate elevations. Areas along the Alaskan Beaufort Sea coast (ABSC) protected by barrier islands showed a three times lower erosion rate on average, suggesting that barrier islands are critical to maintaining mainland shore position. Finally, typologies with the highest erosion rates are not broadly representative of the ABSC and are generally associated with low elevation, north- to northeast-facing shorelines, a peaty pebbly silty lithology, and glaciomarine deposits with high ice content. All else being equal, warmer permafrost is also associated with higher erosion rates, suggesting that warming permafrost temperatures may contribute to higher future erosion rates on permafrost coasts. The suite of typologies can be used to guide future modeling and observational efforts by quantifying the distribution of coastlines with specific landscape characteristics and erosion rates. 

The Arctic is experiencing warming and ecological shifts due to climate change and the compounding effects of polar amplification. Arctic Alaskan coastal marsh environments, such as the Cape Espenberg barrier beach system, offer an opportunity to determine the carbon cycle response to changing climate by examining sediment records that have been preserved through time as shoreline-parallel, linear geometry prograding geomorphic features. This study determines the carbon and mineral accumulation trends in marsh environments at Cape Espenberg for both paleo (~776 CE to 1850 CE) and modern (post-1850 CE) time frames. A comprehensive physical and chemical dataset, including radioisotope (137Cs, 210Pb, 14C), stable isotope (δ13C), element concentration (%C, %N, C:N), and dry bulk density, has been built for several sediment cores. Results indicate that carbon and mineral accumulation rates have increased from paleo to modern times, potentially because of better growing and preservation conditions for organic matter in a modern climate. Paleoclimate trends in the Medieval Climate Anomaly (MCA) and warm periods interspersed within the Little Ice Age (LIA) also correlate with greater contributions of wetland organic matter, as evidenced by lighter δ13C values. Cold climate periods within the LIA correlate with increased aquatic organic matter sourcing and heavier δ13C values, with some spikes of wetland sources interspersed throughout the LIA. Future temperatures are predicted to rise with global climate change, which may continue to expand carbon stores in Arctic coastal wetland sediments. This has been observed in the swale environments at Cape Espenberg, where increasingly favourable growing and soil-preservation conditions (i.e. wet/anoxic soils and lower salinity to limit organic material decay, higher temperatures to promote growth) are increasing the carbon storage within Arctic coastal carbon reservoirs. 

As part of NSF Project 1848542, we assessed the impacts of Bering Sea storms on western Alaskan communities, focusing on Goodnews Bay and St. Paul Island. Field campaigns collected high-resolution coastal datasets to document storm-driven flooding and shoreline change. Cross-shore profiles were surveyed using a Trimble real-time kinematic global navigation satellite system (RTK-GNSS), extending from upland features to the waterline and repeated over time to capture coastal change. High-water marks (HWMs) were also recorded, providing elevation data for present and historic flooding events, including detailed measurements of Typhoon Merbok impacts in 2022. Indicators such as debris lines, seed lines, foam lines, and wet/dry lines were used to approximate total water levels, which integrate astronomical tide, storm surge, and wave runup. This dataset contains supporting tables and measurements from these surveys, which complement a broader assessment of storm flooding impacts on regional infrastructure. We encourage researchers to contact us with questions or requests for additional data. 

The Arctic is experiencing warming and ecological shifts due to climate change and the compounded effects of polar amplification. Arctic Alaskan coastal marsh environments, such as the Cape Espenberg barrier beach system, offers an opportunity to determine the carbon cycle response to changing climate in sediment records that have been preserved through time as a shoreline-parallel, linear geometry prograding geomorphic features. This study determines the carbon and mineral accumulation trends in marsh environments at Cape Espenberg for both paleo (pre 1850 after death [AD]) and modern (post 1850 AD) timeframes. A comprehensive physical and chemical dataset, including radioisotope (Caesium-137 [137Cs], Lead-210 [210Pb], Carbon-14 [14C]), stable isotope (delta-13 Carbon [δ13C]), element concentration (%Carbon [C], %Nitrogen [N], C:N), and dry bulk density, has been built for several sediment cores. Results indicate carbon and mineral accumulations have increased from paleo to modern times, potentially due to better growing and/or preservation conditions for organic matter under a modern climate. Paleoclimate trends in the Medieval Climate Anomaly (MCA), and warm periods interspersed within the Little Ice Age (LIA), also correlate to greater contributions of wetland organic matter as evidenced by lighter δ13C values. Cold climate periods within the Little Ice Age correlate with increased aquatic organic matter sourcing and heavier δ13C values with some spikes of wetland sources interspersed throughout the LIA. Modern warming may potentially continue to expand carbon stores in Arctic coastal wetlands as future temperatures are predicted to rise with global climate change, as observed in the swale environments at Cape Espenberg, where increasingly favorable growing and soil preservation conditions (i.e. wet/anoxic soils and lower salinity to limit organic material decay, higher temperatures to promote growth) may result in future Arctic coastal carbon reservoirs. 

This dataset documents the occurrence, distribution, and characteristics of cryptic ice wedge networks in the Yukon-Kuskokwim Delta (YKD), Alaska. The dataset is derived from remote sensing analyses, field-based permafrost coring, ground-penetrating radar (GPR) surveys, and stable water isotope analyses. High-resolution aerial orthoimagery from 2018 enabled the identification of ~50 linear kilometers (km) of ice wedge trough networks within a 60 square kilometers (km²) study area near Bethel, Alaska, revealing ice wedge networks previously undocumented in the region. Fieldwork in 2023 and 2024 confirmed the presence of ice wedges up to 1.5 meter (m) wide and 2.5 m tall, with wedge tops averaging 0.9 m below the surface. GPR transects identified additional ice wedges beyond those visible in imagery, suggesting that remote sensing analyses may underestimate their true abundance. Coring of polygon centers revealed a suite of late-Quaternary deposits, including early Holocene peat, ice-rich late-Pleistocene permafrost (reworked Yedoma), charcoal layers indicating past tundra fires, and the Aniakchak CFE II tephra (~3,600 calendar years before present [cal yrs BP]). Stable water isotope analyses of wedge ice (mean δ¹⁸O = -15.7 ‰, δ²H = -113.1 ‰) indicate relatively enriched values compared to other Holocene ice wedges in Alaska, reflecting the region's warm maritime climate influence. Expanding the mapping analysis across the YKD using very high-resolution satellite imagery, we found that 95 % of observed ice wedge networks occur at elevations between 4 and 80 meters above sea level (m asl), predominantly within tundra vegetation classes. These areas, covering ~32 % of the YKD tundra region, may contain additional ice wedges, peat deposits, and relict Yedoma. This dataset provides a new framework for understanding the spatial distribution and environmental controls on ice wedge development in warm permafrost regions, with implications for permafrost resilience, climate change vulnerability, and land use planning in the YKD.