Northern high latitudes are projected to get warmer and wetter in the future which will affect rates of permafrost thaw and the mechanisms by which thaw occurs. To better understand these changing thaw dynamics, we instrumented an isolated permafrost plateau in south-central Alaska with climate conditions that currently mirror those expected in more northern permafrost regions in the future. Using preliminary 2019 measurements of temperature from the soil surface into permafrost, depth to frost table, water level, groundwater temperature, and meteorological variables, we tracked soil and permafrost warming throughout the season, and identified how environmental factors, such as water table elevation, microtopography, and warm rain events, affected rates of warming and thaw. Additionally, we present the extent of permafrost degradation since the last observations at this site in 2015. Permafrost thaw and resultant landscape change has a net warming effect on the climate. Understanding of the environmental factors that lead to thaw and rates at which permafrost will thaw under future climate conditions will allow for better preparation, modeling, and policy making for the future.

​​​​​​​​​Lakes in the Arctic are important reservoirs of heat with much lower albedo and larger absorption of solar radiation than surrounding tundra vegetation. Under climate warming scenarios, we expect Arctic lakes to further accelerate thawing underlying permafrost. Previous studies of Arctic lakes have focused on ice cover and thickness, the ice decay process, catchment hydrology, lake water balance, and eddy covariance measurements, but little work has been done in the Arctic to model lake heat balance. We applied the LAKE model to simulate water temperatures in three Arctic lakes in Northern Alaska over several years. The LAKE model is a one-dimensional that explicitly solves vertical profiles of water state variables on a grid. We used a combination of meteorological data from local and remote weather stations, as well as data derived from remote sensing, to drive the model. We validated simulated water temperatures with data of observed lake temperatures at several depths. Our validation of the LAKE model completes a necessary step toward modeling changes in Arctic lake ice regimes, lake heat balance, and thermal interactions with permafrost. Our results showed that winter precipitation and lake ice plays an important role in forming water temperatures over the winter period. Our findings suggest that reduction in the lake ice thickness and ice time period could lead to more heat storage by lakes and further warming of the Arctic.

Declining sea ice in the Arctic Ocean is exposing its coasts to more frequent and intense forms of wave energy and storm surge. As a result, erosion rates along some stretches of coastline in the Alaskan Arctic have doubled since the middle of the 20th century and now rank among the highest in the world. People concentrated near the coast are being heavily impacted by erosion, with some facing relocation. Coastal erosion is projected to increase the cost of maintaining infrastructure by billions of dollars in the coming decades. The financial impact of enhanced erosion will likely be further exacerbated by emerging geopolitical pressures, including the discovery of natural resources, opening of new shipping routes, and construction of support facilities in the Arctic. Scientific knowledge and engineering tools for predicting coastal erosion and guiding land-use decision are not well-suited for the ice-bonded bluffs of the Alaskan Arctic. Investigation of the oceanographic, thermal, and mechanical processes that are relevant to permafrost bluff failure along Arctic coastlines is thus needed. We introduce a geomechanical simulation framework, informed by field observation and laboratory testing, that focuses on the impact of bluff geometry and material variability on permafrost bluff stress states associated with a 9-km stretch of Alaskan Arctic coastline fronting the Beaufort Sea that is prone to toppling-mode block failure. Our approach is advantageous in that it is based on measurable physical properties (e.g., the bluff geometry, permafrost bulk density, Young’s Modulus, and Poisson’s Ratio) and does not require the potential failure to be defined a priori, but rather, the failure area can be interpreted from the multidimensional patterns of stress produced by the model. Our findings highlight how (1) block failure characteristics could be tied to variations in the intensity and duration of the storm energy that intersects the coastline and (2) how deformation processes that create non-uniform patterns of displacement may play a role in localizing block failure. We propose that this kind of physics-based simulation approach can facilitate hypothesis testing regarding the prediction of decadal-scale erosion rates for increasingly dynamic coastal permafrost systems.

Coasts in the Russian Arctic are extremely vulnerable to the ongoing environmental changes. Temporal evolution of their retreat rates is driven by hydrometeorological processes. Permafrost of the coastal bluffs rapidly thaws under the influence of air and water temperature increase. Along with that, sea ice decline results in wave energy increase because of longer wave fetch and ice-free period when the waves are able to erode the unprotected coasts. The combined thermal and wave action is defined as hydrometeorological forcing of coastal erosion. We estimated temporal variability of the air thawing index (sum of annual positive temperatures) reflecting the thermal factor, and the wind-wave energy flux since the 1970s for five sites in both the western and eastern Russian Arctic where observations of coastal erosion rates derived from both field measurements and remotely sensed data are available: Varandey (Pechora Sea), Yamal and Ural coasts of the Baydaratskaya Bay (Kara Sea), Cape Chukochiy (East Siberian Sea) and Lorino (Bering Sea). We further calculated the total hydrometeorological forcing of coastal erosion for the periods with known retreat rates and compared the temporal variability of the two parameters. Comparison of the hydrometeorological forcing shows a link between erosion rates and the hydrometeorological forcing in all the areas. The best correlation is noted for sites where remotely sensed data for relatively long periods were analyzed. For areas with more frequent direct field observations, the variability of the two parameters shows more differences. Such findings imply that while long-term erosion rates are determined by general trends of climate and sea ice extent change in the Arctic seas, coastal retreat in one single year can be driven by local factors, such as lake drainage, random failure of large blocks or peat lenses, exposure and burial of ice bodies, and other reasons. Therefore estimation of mechanisms and trends of coastal erosion in the Russian Arctic should be made based on average retreat rates over relatively long timescales (several years or even decades). Studies on the variability of climate parameters were funded by the RFBR grant 18-05-60300 (S.Ogorodov, N. Shabanova). Studies on rates of coastal erosion were funded by the RSF grant 16-17-00034 (A.Baranskaya, A. Novikova). B.Jones was supported by US National Science Foundation award OISE- 1927553.