By Gunjan Silwal, OnePlanet Doctoral Student
Nepal, a landlocked Himalayan country with 30 million people1, has a strikingly diverse topography. Within just 150–200 km across the width of the nation, its elevation shifts dramatically from the low-lying Terai Plains (~70 m asl) to Mount Everest (8,848 m), the world’s highest peak.
This extreme altitudinal variation creates multiple climatic zones across its relatively small area (147,516 km²), supporting ecosystems ranging from subtropical forests in the south to alpine meadows and glacial landscapes in the north. Nepal’s glaciers form the headwaters of Ganges River, a lifeline for 400 million people2 in the basin.
Climate change is accelerating glacial recession and ice mass loss in the Nepal’s Himalaya, exposing its mountain communities to cascading impacts, including water shortages and increased hazards such as glacial lake outburst floods (GLOFs), avalanches, and rockfalls3. These impacts extend further downstream, exacerbating flood hazards, water insecurity, and economic instability3,4. Glacier recession in Nepal is driven by temperature rises and influenced by ice dynamics e.g. debris cover, lakes and topography.
Overview of Nepal’s Glaciers
A 2010 CE glacier inventory of the Nepal’s Himalaya3 mapped ~3,808 glaciers covering 3,902 km², with an estimated ice reserve of 312 km³. These glaciers, ranging from 3,200 to 8,400 meters above sea level (m asl), have an average size of ~1 km².
The Ngozumpa Glacier (79 km²) in the Everest region is the largest glacier of Nepal. Primarily influenced by the South Asian Monsoon and westerly winds, these glaciers vary in morphology, from small, debris-free cirque glaciers at higher elevations to large, debris-covered valley glaciers at lower altitudes.
12-15% of Nepal’s glaciers are debris-covered and are shaped by complex climate-topography interactions.
Explore the glaciers of the Everest region in the interactive map below.
Trends in Glacier Dynamics
Glacier recession in Nepal
Glacier recession in Nepal has been primarily assessed through remote sensing and limited field studies on benchmark glaciers like Mera, West ChangriNup, and Khumbu (Everest region), Yala and Lirung (Langtang region), and Rikha Samba (Dhaulagiri region). A nationwide study using Landsat satellite images revealed accelerated glacier area loss between the 1977 and 2010, with a 24 % reduction in total glacier area, equivalent to 29 % ice reserve loss3.
This retreat coincided with glacier fragmentation, increasing the total number of glaciers from 3429 in 1977 to 3808 in 2010 CE, an increase by 11 %;, while 163 smaller glaciers (33.71 km²) vanished entirely, with largest changes taking place between 1980- 1990.
Overall, Nepal’s glaciated area declined from 3.6% to 2.6% between 1977 and 20103,6.
Mass Balance Trends: in-situ monitoring
Glacier mass balance in Nepal is studied using two primary methods: glaciological (in-situ monitoring with stake networks and snow pits) and geodetic (satellite imagery and digital elevation models). Field observations since the late 2000s on glaciers such as Yala, Mera, and Rikha Samba reveal a consistent negative mass balance trend.
Glacier mass balance is measured in metres water-equivalent per annum (m w.e. a⁻¹). This is based on the density of snow and ice. A glacier-wide average value of -1.0 m w.e. per year is the same as an annual glacier-wide ice elevation loss of ~1.1 m per year, as the density of ice is 0.9 times the density of water.
Between 2011 and 2017, Yala Glacier lost an average of −0.80 ± 0.28 m w.e. a⁻¹, totalling -4.80 ± 0.69 m w.e., while Rikha Samba lost −0.39 ± 0.32 m w.e. a⁻¹, amounting to -2.34 ± 0.79 m w.e.7. In the Everest region, Mera Glacier lost an average mass of −0.3 ± 0.43 m w.e. a⁻¹ from 2007 to 20198.
In contrast, the smaller West ChangriNup Glacier in the Everest region experienced a much negative mass loss of −1.24 ± 0.33 m w.e. a⁻¹ from 2010 to 20159.
Overall, studies indicate that smaller glaciers in the Nepal’s Himalaya are losing mass more rapidly than larger ones7,9.
Regional mass balance trends from geodetic studies
Geodetic mass balance studies in Nepal have primarily focused on the Langtang and Everest regions.
Langtang region
In Langtang, glacier mass loss has increased significantly over time, averaging –0.45 ± 0.18 m w.e. a⁻¹ from 2006 to 2015—more than twice the rate of –0.21 ± 0.08 m w.e. a⁻¹ from 1974 to 200610. Yala Glacier experienced the highest loss at –0.74 ± 0.53 m w.e. a⁻¹ from 2000- 20127, while clean glaciers in the Langtang subregion had a median loss of –0.58 ± 0.08 m w.e. a⁻¹ from 2000 to 201611.
Explore the glaciers of the Langtang region in the map below.
Everest region
Mass loss rates in the Everest region vary across studies and different time periods. Estimates range from −0.26 ± 0.13 m w.e. a⁻¹ (2000–2011)12 to −0.45 ± 0.60 m w.e. a⁻¹ (2000–2008)13, with a higher rate of −0.79 ± 0.52 m w.e. a⁻¹ between 2002 and 200714. A long-term study around Mt. Everest indicates accelerating mass loss, from -0.23 ± 0.12 m w.e. a⁻¹ (1964–1969) to −0.39 ± 0.13 m w.e. a⁻¹ (2009–2019)15.
The persistent negative mass balance across Nepal’s Himalaya is driven by widespread glacier thinning. This thinning is accompanied by increased debris emergence at higher elevations and the expansion of supraglacial ponds and ice cliffs 10,15. These studies also show that debris-covered glaciers in Nepal recede at similar rates to clean-ice glaciers. Despite some regional differences, all monitored glaciers in Nepal show a clear trend of sustained mass loss.
Glacier Lakes and Glacier Lakes Outburst Floods (GLOFs) in Nepal
Glacial retreat, thinning, and mass loss since the 1970s have caused the rapid expansion of glacial lakes in the Nepal Himalaya. Between 1977 and 2017, the number of glacial lakes grew from 606 to 1,541, with a 25% increase (from 64 km2 to 85 km2) in lake area18.
Of the 1233 lakes mapped across Nepal’s Koshi, Gandaki, and Karnali River basins, 21 are classified as potentially dangerous due to their high risk of Glacial Lake Outburst Floods (GLOFs)19.
GLOFs have become a defining cryospheric hazard in Nepal, yet their risks remain poorly quantified. 26 GLOF events causing significant damage to downstream communities have been recorded so far18. However, many GLOFs remain unreported due to their smaller scale, low impacts or occurrence in uninhabited areas.
Major GLOF events in Nepal include the 1985 Dig Tsho outburst, which destroyed bridges, agricultural lands, and a hydropower plant, and the 2016 Bhotekoshi/Sunkoshi event, which damaged infrastructure and disrupted the Araniko Highway for several days18,19. Recent events, such as the 2021 Melamchi and 2024 Thame GLOFs, were triggered and intensified by extreme rainfall at the beginning and end of the monsoon20.
Monitoring glacier lakes
Tsho Rolpa and Thulagi are among Nepal’s most closely monitored glacial lakes. Despite being partially drained and lowered by three meters in the early 2000s, Tsho Rolpa continues to expand rapidly, now covering 1.6 km², roughly the size of 148 football field and keeping the threat of an outburst alive19,21. Similarly, Imja Lake, once highly hazardous, had also its water level lowered by three meters in 2016 through controlled drainage, and is now thought to be at lower risk of outburst22.
However, as higher elevations continue to warm rapidly and experience extreme precipitation and permafrost degradation, mountain slopes are becoming increasingly unstable. This instability raises the risk of rock-ice avalanches reaching glacial lakes and triggering outbursts21,22,23. Consequently, GLOF risks in Nepal are expected to rise, posing a growing threat to communities and infrastructure19,22.
Rising temperatures are a major Driver of glacier changes in Nepal Himalaya
One of the primary drivers of glacier change in the Nepal Himalaya is the rising air temperatures and enhanced warming at higher elevations over the last decades. Nepal’s mean annual temperature has increased by 0.027°Cyr-1 and at higher elevations (>2000) by 0.03 °Cyr-1 from 1975-201524, a rate slightly greater than the global average (0.015-0.02 °Cyr-1)25.
This warming is compounded by shifting precipitation patterns, as changes in the intensity and timing of the monsoon have led to reduced snowfall and increased rainfall at higher elevations26. These trends, along with warmer and drier winter months, have significantly exacerbated glacier melt in recent decades.
Topography, debris cover and lakes influence glacier mass loss
Non-climatic factors also play a critical role in glacier dynamics. Topography, for instance, influences retreat rates, with glaciers on steep slopes or with complex geometries experiencing faster melting and fragmentation7,27. Debris cover further complicates glacier behaviour10,15,27. While thick debris layers can insulate glaciers and reduce melting, thin layers (<2 cm) often enhance melting by lowering surface albedo and observing more solar radiation. Additionally, the formation and expansion of supraglacial lakes and ice cliffs, which are becoming increasingly prevalent, accelerate mass loss by concentrating meltwater and intensifying ice-albedo feedback and back wasting 10,15,27.
Future Projections of Nepal’s Glacier
A nationwide future glacier projection in Nepal has not yet been conducted. However, a few regional-scale glacier modelling studies suggest that glaciers across High Mountain Asia (HMA) could lose one-third of their volume by the end of the 21st century if global temperature rise is limited to 1.5°C28,29. If Nepal’s glaciers follow a similar trend, a comparable loss is likely.
The 1.5°C target, however, is highly ambitious and only projected by a few conservative climate models under the IPCC’s Representative Concentration Pathways- RCP2.6 scenario. More likely scenarios—RCP4.5, RCP6.0, and RCP8.5—project glacier mass losses of 49±7 %, 51±6 %, and 64±5 %, respectively, by the end of century 28, 29. Similar trends are observed under the IPCC’s Shared Socio-economic Pathways (SSP) scenarios30.
A few basins wide glacier projection studies conducted in Nepal show greater glacier volume loss by the end of 21st century. For instance, in Koshi River basin, 76–86 % of glacier volume loss is projected under RCP4.5 and RCP8.531. Similarly, Karnali River basin is expected to lose 50–80 % of its glacier volume by 2100 under SSP126 and SSP58532.
Field observations of key glaciers, such as Yala, West ChangriNup, and AX010, also show significant retreat and mass loss. Yala Glacier, now listed among the world’s most endangered, is expected to vanish by 204033.
About the Author
Gunjan Silwal is a PhD student at Newcastle University.
Before joining my PhD here at Newcastle University in the School of Geography, Politics, and Sociology, I worked as a research associate glaciologist at the International Centre for Integrated Mountain Development (ICIMOD) and Kathmandu University (KU) in Nepal. Consequently, I had numerous opportunities to participate in several glacier fieldwork expeditions and led a few in the Langtang and the Dhaulagiri Himal.