Focus on Thermokarst Lakes in Indian Himalaya: Inception and Implication under Warming Climate

Abstract

Thermokarst (Thaw) lakes are landforms found in topographic depressions created by thawing ground ice in permafrost zones. They play an important role in the regulation of climatic functions. These lakes are a manifestation of warming surface temperatures that accelerates the ice-rich permafrost to degrade by creating marshy hollows/ponds. In the current global warming scenario, the thermokarst lakes in the high mountain regions (Himalaya) are expected to grow further. This accelerate permafrost thawing which will affect the carbon cycle, hydrology and local ecosystems. This phenomenon has attracted huge scientific attention because it has led to a rapid mass change of glaciers in the region, including extensive changes occurring on peri-glacial environments. The most striking fact is the release of an enormous amount of greenhouse gases, including methane, carbon dioxide and nitrous oxide that is locked in these lakes. The present study delves into the thermokarst lakes in the upper reaches of Chandra Valley and Western Himalaya. The study also aims at designating the impact of their changes on the ecosystem, particularly their influence on the atmospheric greenhouse gas concentrations.

Modelling Permafrost Distribution in Western Himalaya Using Remote Sensing and Field Observations

“…The first location used for the validation of our result was Chang La Pass near Leh, Ladakh. The permafrost occurrences have been suggested to occur at a shallow depth throughout Taglang La and Chang La Passes [40]. To validate our results, we have chosen the northern slopes of Chang La, as our results indicated presence of continuous permafrost at this location (Figure 6).…”

“…The land cover was obtained from cloud free Landsat 8 [82] datasets available between 2017 and 2019. The presence of prominent features, such as rock glaciers, gelifluctions, perennial snow patches, modification, the degradation of slopes, and thermokarst lakes manifest the presence of permafrost [40,[83][84][85]. However, the areas covered by the glaciers, lakes, and water bodies are generally considered to be an indicator of permafrost absence.…”

“…Between Chandra River and Chandra Taal Lake, the formation of periglacial geomorphological features, which includes thermokarst lakes, mounds, and channels, are visible indicators of the presence of permafrost in the region (Figure 7). Several thawed depressions filled with water (thermokarst lakes) and small frost mounds have formed in the locations, which are a good indicator of ice-rich permafrost in the region [40]. It has been observed that in some continuous permafrost zones, beaded drainage develops when small, thawed pools join [115][116][117] (Figure 7).…”

“…While a wealth of studies are available on the status of Himalayan glaciers (e.g., [24][25][26][27][28][29][30][31][32]), glacier dynamics (e.g., [33,34]), glacier mapping (e.g., [33][34][35][36][37]), crevasse mapping (e.g., [38]), glacial lake mapping (e.g., [39][40][41]), melt-water geochemistry (e.g., [42,43]), and discharge reconstruction (e.g., [44,45]), the permafrost distribution and the potential impact of its thaw is largely unknown for the most part of the Himalaya [46]. In recent years, several studies have investigated permafrost in the Tibetan plateau [47,48], Hindu Kush-Himalaya (HKH) [49], and Nepalese Himalaya [50].…”

Grand Challenges of Hydrologic Modeling for Food-Energy-Water Nexus Security in High Mountain Asia

“…Potential impacts of permafrost degradation in response to climate warming include alterations to the surface energy budget due to changes in freeze-thaw cycles, alterations to soil moisture profiles, and a dropping of the groundwater table (Cheng and Wu, 2007). The growth of thermokarst lakes in HMA permafrost areas are also of concern given their impact on ecosystems, hydrology and emission of greenhouse gasses (Pandey et al, 2020, Gao et al, 2021. We did not incorporate permafrost into any of our analyses; below, we recommend the importance of considering permafrost in future assessments.…”