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 km2 coastline 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.

Glacial lake outburst floods (GLOFs) are a severe hazard in the Himalayas. Glacial lake expansion and the corresponding volume increase play major roles in GLOFs as well as climate change. Furthermore, mass movement and dam conditions play a major role in the GLOF initiation process. Recently, because of global warming, glacial lakes in the central Himalayas have been expanding rapidly. Owing to a lack of systematic assessment and meticulous field surveys, people living downstream are at great risk of GLOFs. Comprehensive investigations and assessment of the relationships among lake expansion, lake dam conditions, and GLOF risk are urgently needed. In this study, we surveyed Jialong Co, a typical end-moraine dammed lake in Poiqu River in the central Himalayas by using Landsat and Sentinel satellite images from the past 32 years, field work, and depth measurements using an unmanned surface vessel on August 28, 2020. The results showed that Jialong Co had experienced slow-quick-slow expansion, increasing in area from 0.13 +/- 0.03 to 0.60 +/- 0.02 km(2). The lake bathymetric map revealed that the lake volume was (3.75 +/- 0.38) x 10(7) m(3) in 2020. Lake expansion occurred in the area from which the mother glacier retreated, indicating a close connection between the lake and its mother glacier and revealing that topography controlled the lake expansion process. Furthermore, thorough field work revealed that outlet dynamics and external water erosion are vulnerable elements in the disaster chain that initiate and affect the GLOF hazard of Jialong Co. Overall, this case study could help scholars understand the expansion mechanism of end-moraine dammed lakes and aid in hazard assessment of glacial lakes in the central Himalayas. (C) 2021 Elsevier B.V. All rights reserved.

With changing climatic conditions and increasing infrastructure demands, infrastructure owners, operators, and planners must possess tools to objectively aid their decisions on climate change adaptation and infrastructure maintenance. Risk analysis tools, either qualitative or quantitative, would be very beneficial to select engineering designs and allocate funds for the expected maintenance of linear infrastructure on permafrost. To this end, the paper provides an example application of a newly developed Excel spreadsheet, called Arquluk-RISK, which quantitatively calculates hazard and risk based on site soil, permafrost, and climate condition variabilities. This example focuses on the hazard analysis of total and differential thaw settlement, active layer detachment slides, and culvert collapse and gradient failure for current climate conditions for the airport access road in Salluit, Nunavik (northern Quebec), Canada. The software and analysis includes the variation in hazard due to increasing mean annual air temperature in the coming decades.