Abstract Glaciers in the Sikkim Himalayas have undergone significant retreat over the past six decades, with an accelerated loss after 2000. This study analyses glacier changes using satellite data of the years 1962, 1988, 2002, and 2023. Results indicate a 39.30% reduction in glacier area and a 45.12% decrease in glacier count, with smaller glaciers (<2 km2) being disproportionately affected. ERA5 climate data reveals rising regional minimum temperatures and shifting precipitation patterns, contributing to an enhanced glacier melt. While annual precipitation has increased, seasonal snowfall shows varied trends, with a significant decline during summer and autumn seasons. This warming, coupled with reduced summer and autumn snowfall, is shifting precipitation from snow to rain, accelerating glacier melt and hindering accumulation. South-facing glaciers exhibited higher retreat rates, consistent with enhanced solar radiation exposure. Additionally, cryokarst features, particularly proglacial lakes, evolve on the surface and may expand into extensive lake systems, thereby heightening the susceptibility to dam breach events. A pertinent example is the South Lhonak Lake, which raised significant concern regarding a glacial lake outburst flood (GLOF) in 2023, thereby posing substantial risks to downstream communities. These glacial changes have critical implications for hydrological systems, particularly for the Teesta River, which is highly dependent on glacier meltwater. Uncertainty analysis, quantified using a buffer-based estimation method (e.g., average positional uncertainties ranging from 0.8% to 7.4% for different imagery), highlights the inherent limitations of remote sensing data in precisely delineating glacier boundaries. The findings underscore the need for continued glacier monitoring, higher-resolution climate modelling, and improved risk management strategies to address the ongoing impacts of glacier retreat in the Sikkim Himalaya. Research highlights <UnorderedList Mark="Bullet"> <ItemContent> A multi-decadal analysis (1962–2023) of the Sikkim Himalaya reveals a 39.30% reduction in total glacier area anda 45.12% decline in glacier count. </ItemContent> <ItemContent> Smaller glaciers (<2 km2) demonstrate disproportionate vulnerability and accelerated disappearance due to theirhigher surface-area-to-volume ratios. </ItemContent> <ItemContent> Accelerated glacier loss post-2000 is directly driven by rising regional temperatures and critically decliningsummer and autumn snowfall. </ItemContent> <ItemContent> Topographic analysis confirms that south-facing glaciers experience significantly higher retreat rates owing toincreased solar radiation exposure. </ItemContent> <ItemContent> The rapid expansion of proglacial lakes, particularly South Lhonak, underscores an escalating and immediate riskof Glacial Lake Outburst Floods (GLOFs). </ItemContent> </UnorderedList>

Disappearing glaciers of Sikkim Himalaya: a multi-decadal remote sensing analysis

期刊论文
发表日期：

2026年4月4日

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Bidyutjyoti Baruah,
Rajeev Rajak,
Aparna Gupta,
Khushboo Sharma,
Ankita Roy,
Swati Yadav,
Shruti Dutta,
Vinay Kumar Gaddam,
Mohd Ramiz,
Rakesh Kumar Ranjan

摘要

Abstract

Glaciers in the Sikkim Himalayas have undergone significant retreat over the past six decades, with an accelerated loss after 2000. This study analyses glacier changes using satellite data of the years 1962, 1988, 2002, and 2023. Results indicate a 39.30% reduction in glacier area and a 45.12% decrease in glacier count, with smaller glaciers (<2 km²) being disproportionately affected. ERA5 climate data reveals rising regional minimum temperatures and shifting precipitation patterns, contributing to an enhanced glacier melt. While annual precipitation has increased, seasonal snowfall shows varied trends, with a significant decline during summer and autumn seasons. This warming, coupled with reduced summer and autumn snowfall, is shifting precipitation from snow to rain, accelerating glacier melt and hindering accumulation. South-facing glaciers exhibited higher retreat rates, consistent with enhanced solar radiation exposure. Additionally, cryokarst features, particularly proglacial lakes, evolve on the surface and may expand into extensive lake systems, thereby heightening the susceptibility to dam breach events. A pertinent example is the South Lhonak Lake, which raised significant concern regarding a glacial lake outburst flood (GLOF) in 2023, thereby posing substantial risks to downstream communities. These glacial changes have critical implications for hydrological systems, particularly for the Teesta River, which is highly dependent on glacier meltwater. Uncertainty analysis, quantified using a buffer-based estimation method (e.g., average positional uncertainties ranging from 0.8% to 7.4% for different imagery), highlights the inherent limitations of remote sensing data in precisely delineating glacier boundaries. The findings underscore the need for continued glacier monitoring, higher-resolution climate modelling, and improved risk management strategies to address the ongoing impacts of glacier retreat in the Sikkim Himalaya.

Research highlights

A multi-decadal analysis (1962–2023) of the Sikkim Himalaya reveals a 39.30% reduction in total glacier area anda 45.12% decline in glacier count.

Smaller glaciers (<2 km²) demonstrate disproportionate vulnerability and accelerated disappearance due to theirhigher surface-area-to-volume ratios.

Accelerated glacier loss post-2000 is directly driven by rising regional temperatures and critically decliningsummer and autumn snowfall.

Topographic analysis confirms that south-facing glaciers experience significantly higher retreat rates owing toincreased solar radiation exposure.

The rapid expansion of proglacial lakes, particularly South Lhonak, underscores an escalating and immediate riskof Glacial Lake Outburst Floods (GLOFs).