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One of the most conspicuous signals of climate change in high‐latitude tundra is the expansion of ice wedge thermokarst pools. These small but abundant water features form rapidly in depressions caused by the melting of ice wedges (i.e., meter‐scale bodies of ice embedded within the top of the permafrost). Pool expansion impacts subsequent thaw rates through a series of complex positive and negative feedbacks which play out over timescales of decades and may accelerate carbon release from the underlying sediments. Although many local observations of ice wedge thermokarst pool expansion have been documented, analyses at continental to pan‐Arctic scales have been rare, hindering efforts to project how strongly this process may impact the global carbon cycle. Here we present one of the most geographically extensive and temporally dense records yet compiled of recent pool expansion, in which changes to pool area from 2008 to 2020 were quantified through satellite‐image analysis at 27 survey areas (measuring 10–35 km2 each, or 400 km2 in total) dispersed throughout the circumpolar tundra. The results revealed instances of rapid expansion at 44% (± $\pm $15%) of survey areas. Considered alone, the extent of departures from historical mean air temperatures did not account for between site variation in rates of change to pool area. Pool growth was most clearly associated with upland (i.e., hilly) terrain and elevated silt content at soil depths greater than one meter. These findings suggest that, at short time scales, pedologic and geomorphologic conditions may exert greater control on pool dynamics in the warming Arctic than spatial variability in the rate of air temperature increases. Plain Language Summary: Ice wedge thermokarst pools are meter‐scale water features with a distinctive shape that form on the tundra in response to permafrost thaw. They occupy pits in the ground surface caused by the melting of ice wedges, or subsurface ice bodies which form an interconnected network that manifests at the surface as polygonal ground. Ice wedge thermokarst pool growth not only signals permafrost thaw, but also creates feedbacks on subsequent thaw by altering the surface energy balance, which may accelerate carbon release from permafrost‐affected soils. There are many prior observations of pool growth, but they have typically been locally or regionally focused, and circumpolar analyses are rare. We analyzed recent (2008–2020) time series of sub‐meter resolution satellite imagery at 27 survey areas throughout the Arctic to create one of the largest observational records yet of ice wedge thermokarst pool extent. We then analyzed which environmental and meteorological factors have been most strongly associated with recent trends in pool area at the circumpolar scale. Overall, we found evidence for recent pool growth at 44% (± $\pm $15%) of the survey areas. There was no difference in the recent rate of air temperature increase between sites with and without expanding pools. However, sites with ice wedge thermokarst pool expansion were hillier and had more silt‐rich soils than sites with stable or shrinking pools. Key Points: Decadal‐scale thermokarst pool expansion was observed at 12 (plus or minus 4) of 27 landscapes monitored throughout the ArcticExpanding thermokarst pools were most likely to be found in topographically convex positions within hilly landscapesTrends in air temperature alone were a poor predictor of recent thermokarst pool expansion [ABSTRACT FROM AUTHOR]

Arctic soil microbial communities may shift with increasing temperatures and water availability from climate change. We examined temperature and volumetric liquid water content (VWC) in the upper 80 cm of permafrost-affected soil over 2 years (2018-2019) at the Bayelva monitoring station, Ny Ålesund, Svalbard. We show VWC increases with depth, whereas in situ temperature is more stable vertically, ranging from -5°C to 5 °C seasonally. Prokaryotic metagenome-assembled genomes (MAGs) were obtained at 2-4 cm vertical resolution collected while frozen in April 2018 and at 10 cm vertical resolution collected while thawed in September 2019. The most abundant MAGs were Acidobacteriota, Actinomycetota, and Chloroflexota. Actinomycetota and Chloroflexota increase with depth, while Acidobacteriota classes Thermoanaerobaculia Gp7-AA8, Blastocatellia UBA7656, and Vicinamibacteria Vicinamibacterales are found above 6 cm, below 6 cm, and below 20 cm, respectively. All MAGs have diverse carbon-degrading genes, and Actinomycetota and Chloroflexota have autotrophic genes. Genes encoding β -glucosidase, N-acetyl-β-D-glucosaminidase, and xylosidase increase with depth, indicating a greater potential for organic matter degradation with higher VWC. Acidobacteriota dominate the top 6 cm with their classes segregating by depth, whereas Actinomycetota and Chloroflexota dominate below ∼6 cm. This suggests that Acidobacteriota classes adapt to lower VWC at the surface, while Actinomycetota and Chloroflexota persist below 6 cm with higher VWC. This indicates that VWC may be as important as temperature in microbial climate change responses in Arctic mineral soils. Here we describe MAG-based Seqcode type species in the Acidobacteriota, Onstottus arcticum, Onstottus frigus, and Gilichinskyi gelida and in the Actinobacteriota, Mayfieldus profundus., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier GmbH.)

Purpose: This study aimed to present the institutional experience and algorithm for performing biliary interventions in liver transplant patients using the modified Hutson loop access (MHLA) and the impact of percutaneous endoscopy via the MHLA on these procedures., Methods: Over 13 years, 201 MHLA procedures were attempted on 52 patients (45 liver transplants; 24 living and 21 deceased donors) for diagnostic (e.g., cholangiography) and therapeutic (e.g., stent/drain insertion and cholangioplasty) purposes. The most common indications for MHLA were biliary strictures (60%) and bile leaks (23%). Percutaneous endoscopy was used to directly visualize the biliary-enteric anastomosis, diagnose pathology (e.g., ischemic cholangiopathy), and help in biliary hygiene (removing debris/casts/stones/stents) in 138/201 (69%) procedures. Technical success was defined as cannulating the biliary-enteric anastomosis and performing diagnostic/therapeutic procedure via the MHLA., Results: The technical success rate was 95% (190/201). The failure rate among procedures performed with and without endoscopy was 2% (3/138) versus 13% (8/63) (P = 0.0024), and the need for new transhepatic access (to aid the procedure) was 12% (16/138) versus 30% (19/63) (P = 0.001). Despite endoscopy, failure in 2% of the cases resulted from inflamed/friable anastomosis (1/3) and high-grade stricture (2/3) obstructing retrograde cannulation of biliary-enteric anastomosis. Major adverse events (bowel perforation and injury) occurred in 1% of the procedures, with no procedure-related mortality., Conclusions: MHLA-based percutaneous biliary intervention is a safe and effective alternative to managing complications after liver transplant. Percutaneous endoscopy via the MHLA improves success rates and may reduce the need for new transhepatic access. Level of Evidence Level 4., (© 2024. Springer Science+Business Media, LLC, part of Springer Nature and the Cardiovascular and Interventional Radiological Society of Europe (CIRSE).)