Temporal inventory of glaciers in the Suru sub-basin, western Himalaya: impacts of regional climate variability

• Main Authors: A. Shukla, S. Garg, M. Mehta, V. Kumar, U. K. Shukla
• Format: Article
• Language: English
• Published: Copernicus Publications 2020-06-01
• Series: Earth System Science Data
• Online Access: https://www.earth-syst-sci-data.net/12/1245/2020/essd-12-1245-2020.pdf

<p>The importance of updated knowledge about the glacier extent and characteristics in the Himalaya cannot be overemphasized. Availability of precise glacier inventories in the latitudinally diverse western Himalayan region is particularly crucial. In this study we have created an inventory of the Suru sub-basin in the western Himalaya for the year 2017 using Landsat Operational Land Imager (OLI) data. Changes in glacier parameters have also been monitored from 1971 to 2017 using temporal satellite remote-sensing data and limited field observations. Inventory data show that the sub-basin has 252 glaciers covering 11&thinsp;% of the basin, having an average slope of <span class="inline-formula">25±<i>6</i></span><span class="inline-formula">^∘</span> (standard deviations have been italicized throughout the text) and dominantly north orientation. The average snow line altitude (SLA) of the basin is <span class="inline-formula">5011±<i>54</i></span>&thinsp;m&thinsp;a.s.l. with smaller (47&thinsp;%) and cleaner (43&thinsp;%) glaciers occupying the bulk area. Long-term climate data (1901–2017) show an increase in the mean annual temperature (<span class="inline-formula"><i>T</i>_max⁡</span> and <span class="inline-formula"><i>T</i>_min⁡</span>) of 0.77&thinsp;<span class="inline-formula">^∘</span>C (0.25 and 1.3&thinsp;<span class="inline-formula">^∘</span>C) in the sub-basin, driving the overall glacier variability in the region. Temporal analysis reveals a glacier shrinkage of <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M8" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>∼</mo><mn mathvariant="normal">6</mn><mo>±</mo><mn mathvariant="normal">0.02</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="51pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="7b88cdc982a84ac4f4599cb577080bd1"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="essd-12-1245-2020-ie00001.svg" width="51pt" height="10pt" src="essd-12-1245-2020-ie00001.png"/></svg:svg></span></span>&thinsp;%, an average retreat rate of <span class="inline-formula">4.3±1.02</span>&thinsp;m&thinsp;a<span class="inline-formula">⁻¹</span>, debris increase of 62&thinsp;% and a <span class="inline-formula">22±<i>60</i></span>&thinsp;m SLA increase in the past 46 years. This confirms their transitional response between the Karakoram and the Greater Himalayan Range (GHR) glaciers. Besides, glaciers in the sub-basin occupy two major ranges, the GHR and Ladakh Range (LR), and experience local climate variability, with the GHR glaciers exhibiting a warmer and wetter climate as compared to the LR glaciers. This variability manifests itself in the varied response of GHR and LR glaciers. While the GHR glaciers exhibit an overall rise in SLA (GHR: <span class="inline-formula">49±<i>69</i></span>&thinsp;m; LR: decrease of <span class="inline-formula">18±<i>50</i></span>&thinsp;m), the LR glaciers have deglaciated more (LR: 7&thinsp;%; GHR: 6&thinsp;%) with an enhanced accumulation of debris cover (LR: 73&thinsp;%; GHR: 59&thinsp;%). Inferences from this study reveal prevalence of glacier disintegration and overall degeneration, transition of clean ice to partially debris-covered glaciers, local climate variability and non-climatic (topographic and morphometric)-factor-induced heterogeneity in glacier response as the major processes operating in this region. The Shukla et al. (2019) dataset is accessible at <span class="uri">https://doi.org/10.1594/PANGAEA.904131</span>.</p>