Review article: Inferring permafrost and permafrost thaw in the mountains of the Hindu Kush Himalaya region

Abstract

Abstract. The cryosphere reacts sensitively to climate change, as evidenced by the widespread retreat of mountain glaciers. Subsurface ice contained in permafrost is similarly affected by climate change, causing persistent impacts on natural and human systems. In contrast to glaciers, permafrost is not observable spatially and therefore its presence and possible changes are frequently overlooked. Correspondingly, little is known about permafrost in the mountains of the Hindu Kush Himalaya (HKH) region, despite permafrost area exceeding that of glaciers in nearly all countries. Based on evidence and insight gained mostly in other permafrost areas globally, this review provides a synopsis on what is known or can be inferred about permafrost in the mountains of the HKH region. Given the extreme nature of the environment concerned, it is to be expected that the diversity of conditions and phenomena encountered in permafrost exceed what has previously been described and investigated. We further argue that climate change in concert with increasing development will bring about diverse permafrost-related impacts on vegetation, water quality, geohazards, and livelihoods. To better anticipate and mitigate these effects, a deepened understanding of high-elevation permafrost in subtropical latitudes as well as the pathways interconnecting environmental changes and human livelihoods are needed.

New insights into the environmental factors controlling the ground thermal regime across the Northern Hemisphere: a comparison between permafrost and non-permafrost areas

“…Although temporal dynamics of ALT are beyond our analyses, our findings suggest that thaw depth and air temperatures are, to a degree, decoupled by local conditions. Recent warming trends in the atmosphere (Guo et al, 2017) are already very visible in circumpolar permafrost temperature observations Bisk-aborn et al, 2019), implying that the permafrost system will remain dynamic in the future's changing climate. Warmer air temperatures will occur mostly during winters (AMAP, 2017;Guo et al, 2017), which, given the presented high contribution of FDD to MAGT, suggests that changes are foreseeable.…”

Influences of Topographic Shadows on the Thermal and Hydrological Processes in a Cold Region Mountainous Watershed in Northwest China

“…For example, the solar radiation arriving on some unobstructed south-facing slopes would far exceed that on a horizontal plane, and it would be much diminished in valleys or on north facing slopes (Aguilar et al, 2010). A spatial interpolation method based on few sparsely installed stations cannot effectively capture the spatial heterogeneity of solar radiation in a mountainous area, which will exert significant influences on the spatial distribution of air and ground temperatures, ET, snowmelt, and mass balance of mountainous glaciers (Gruber et al, 2017;Harris et al, 2009;Hasler et al, 2015;Hoffman et al, 2016;Luo, Jin, Marchenko, et al, 2018;Luo, Jin, Wu, et al, 2018;van Pelt et al, 2012). According to observations in the Antarctica dry valley, the ground surface temperature dropped by about 10°C in less than 4 hr following the onset of topographic shadows (Katurji et al, 2013).…”

Glacial lake outburst flood hazard assessment by satellite Earth observation in the Himalayas (Chomolhari area, Bhutan)

“…The maximum discharge [Q max ] for a worst-case scenario, related to the ice dam suddenly breaking, is calculated by assuming mean drainage duration [t] of 1000 s for maximum estimates as proposed in Haeberli's (1983) empirical relationship (Huggel et al, 2004(Huggel et al, : 1071. According to Huggel et al (2002: 322), the lake volume can be doubled in the case of outbursts from moraine-dammed lakes:…”

“…Thanks to satellite Earth observation (EO), hazard assessments of glacial lake outburst floods (GLOFs) were performed in several mountain chains of the world, including the Alps (e.g. Haeberli, 1983;Huggel et al, 2004;Haeberli et al, 2001), the Andes (e.g. Schneider et al, 2014;Schaub et al, 2015;Frey et al, 2016) and the Himalayas (e.g.…”