Search for: All records

The degradation of permafrost alters deformation and long-term strength, posing challenges to existing and future civil infrastructure in Northern Alaska. Long-term strength is a critical parameter in the design of civil projects; yet, to our best knowledge, data on the creep deformation and long-term strength of undisturbed permafrost in Northern Alaska remain limited. Soil particle fraction, unfrozen water content, temperature, and salinity may interactively affect creep deformation and long-term strength of permafrost; however, their interactive effects are not well understood. In this study, field samples of relatively undisturbed permafrost from the upper 1.5 m of the Arctic Coastal Plain near Utqiaġvik, Alaska, were first retrieved and analyzed. The permafrost was characterized as saline ice-rich silty sand and nonuniformly distributed ice. We conducted constant stress creep tests, unconfined compression strength tests, and unfrozen water content tests to assess the mechanical and physical properties of the permafrost cores. The results indicated that the long-term strength of the permafrost decreased by nearly 90% from −10°C to −2°C. At −10°C, the long-term strength increased by approximately 120% as the soil particle fraction rose from 0.14 to 0.26. The strengthening effect of soil particles diminished at higher temperatures and higher salinity due to the influence of unfrozen water. A quantitative tool has been developed to predict the long-term strength of ice-rich permafrost, incorporating the effects of soil particle fraction and temperature. The findings of this study can potentially support infrastructure design and planning in Northern Alaska in the context of a warming climate. 

The Arctic is experiencing accelerated warming at up to four times the rate of temperate regions, driving permafrost thawing and ground ice melting, which, in turn lead to coastal bluff failure and accelerated erosion. The primary mechanisms behind Arctic coastal bluff failures include the formation of thermoerosional niches at the bluff’s toe and warming-induced reductions in ground strength, making Arctic coastal bluff failure a complex thermal-mechanical coupling process. Most existing studies have focused on coastal bluff failures in temperate regions, but the unique failure mechanism in the Arctic remain underexplored. This study addresses this gap by developing a thermalmechanical coupling model to study the failure mechanism of a permafrost bluff failure that occurred in 2023–2024 in Utqia˙gvik, Alaska. The model incorporates pore ice phase change, thaw-induced reductions in permafrost stiffness and strength, and the effects of thermoerosional niches, cracks, and ice wedges. Stability analysis is conducted via the local factor of safety (LFS) method to account for spatial variations in permafrost strength and stiffness. Ground-penetrating radar (GPR) data from the August 2024 site survey were employed to characterize site conditions, and ground temperature data were used to validate the model. The results revealed two primary failure zones: one near the ground surface and another at the bluff’s toe. The total area of these two failure zones expanded with ongoing thaw. Besides, the results indicated that the increase in thaw thickness, the growth in niche length, and the presence of cracks exacerbate bluff instability, and bluff failure is likely to initiate along the ice wedge–permafrost interface. 

This project is part of Navigating the New Arctic (NNA) which addresses converging scientific challenges in the rapidly changing Arctic. Specifically, the goal of this project, is to better understand the effects climate change imposes on society and the built environment and develop risk assessments for future adaptive planning. This dataset provides ground temperature data in the active layer and near-surface permafrost to provide a baseline for assessing the future changes in the near-surface temperatures in the natural and disturbed environment in the vicinity of the city of Fairbanks, Alaska, United States and the city of Whitehorse, Yukon, Canada. Collected ground temperature data are intended to help researchers, communities and public with ongoing activities to mitigate a threat of thawing permafrost on the local and regional scale, and to provide spatial data for validation of climate scenario models and temperature reanalysis approaches. 

This project is part of Navigating the New Arctic (NNA) which addresses converging scientific challenges in the rapidly changing Arctic. Specifically, the goal of this project is to better understand ice-rich permafrost at local, regional, and circumpolar scales. This dataset provides ground temperature data in the active layer and near-surface permafrost to provide a baseline for assessing the future changes in the near-surface temperatures in the natural environment and next to the infrastructure/disturbed environment at Utqiagvik, Point Lay, and Wainwright in Alaska. Collected ground temperature data are intended to help researchers, communities and public with ongoing activities to mitigate a threat of thawing permafrost on the local and regional scale, and to provide spatial data for validation of climate scenario models and temperature reanalysis approaches. Update: Filename nomenclature has been changed from US_PIP_### to US_UTQ_### in order to separate different site location data. 

This work coordinates data collection using standard equipment and protocols at North American and Russian sites. These data sets provide the baseline to assess the future rates of change in near-surface permafrost temperatures and permafrost boundaries, and to provide spatial data for validation of climate scenario models and temperature reanalysis approaches. The work represents the United States (US) contribution to the ongoing activities of the Global Terrestrial Network for Permafrost that obtains temperatures in a large number of globally distributed monitoring sites in order to provide a snapshot of permafrost temperatures in both time and space. The US National Science Foundation (NSF) funded this work with award #0520578, #0632400, #0856864, and #1304271. 

This work coordinates data collection using standard equipment and protocols at North American and Russian sites. These data sets provide the baseline to assess the future rates of change in near-surface permafrost temperatures and permafrost boundaries, and to provide spatial data for validation of climate scenario models and temperature reanalysis approaches. The work represents the United States (US) contribution to the ongoing activities of the Global Terrestrial Network for Permafrost that obtains temperatures in a large number of globally distributed monitoring sites in order to provide a snapshot of permafrost temperatures in both time and space. The US National Science Foundation funded this work with award #0520578, #0632400, #0856864, and #1304271. 

Abstract The thawing of permafrost in the Arctic has led to an increase in coastal land loss, flooding, and ground subsidence, seriously threatening civil infrastructure and coastal communities. However, a lack of tools for synthetic hazard assessment of the Arctic coast has hindered effective response measures. We developed a holistic framework, the Arctic Coastal Hazard Index (ACHI), to assess the vulnerability of Arctic coasts to permafrost thawing, coastal erosion, and coastal flooding. We quantified the coastal permafrost thaw potential (PTP) through regional assessment of thaw subsidence using ground settlement index. The calculations of the ground settlement index involve utilizing projections of permafrost conditions, including future regional mean annual ground temperature, active layer thickness, and talik thickness. The predicted thaw subsidence was validated through a comparison with observed long-term subsidence data. The ACHI incorporates the PTP into seven physical and ecological variables for coastal hazard assessment: shoreline type, habitat, relief, wind exposure, wave exposure, surge potential, and sea-level rise. The coastal hazard assessment was conducted for each 1 km²coastline of North Slope Borough, Alaska in the 2060s under the Representative Concentration Pathway 4.5 and 8.5 forcing scenarios. The areas that are prone to coastal hazards were identified by mapping the distribution pattern of the ACHI. The calculated coastal hazards potential was subjected to validation by comparing it with the observed and historical long-term coastal erosion mean rates. This framework for Arctic coastal assessment may assist policy and decision-making for adaptation, mitigation strategies, and civil infrastructure planning. 

This project is part of Navigating the New Arctic (NNA) which addresses converging scientific challenges in the rapidly changing Arctic. Specifically, the goal of this project, is to better understand the effects climate change imposes on society and the built environment and develop risk assessments for future adaptive planning. This dataset provides ground temperature data in the active layer and near-surface permafrost to provide a baseline for assessing the future changes in the near-surface temperatures in the natural and disturbed environment in the vicinity of the city of Fairbanks, Alaska. Collected ground temperature data are intended to help researchers, communities and public with ongoing activities to mitigate a threat of thawing permafrost on the local and regional scale, and to provide spatial data for validation of climate scenario models and temperature reanalysis approaches. 

This project is part of Navigating the New Arctic (NNA) which addresses converging scientific challenges in the rapidly changing Arctic. Specifically, the goal of this project is to better understand ice-rich permafrost at local, regional, and circumpolar scales. This dataset provides ground temperature data in the active layer and near-surface permafrost to provide a baseline for assessing the future changes in the near-surface temperatures in the natural environment and next to the infrastructure/disturbed environment at Utqiagvik, Alaska. Collected ground temperature data are intended to help researchers, communities and public with ongoing activities to mitigate a threat of thawing permafrost on the local and regional scale, and to provide spatial data for validation of climate scenario models and temperature reanalysis approaches.