Asejiaguo Glacier drains east from the China-Nepal border and is at the headwaters of the Yarlung Tsangpo, which becomes the Brahmaputra River. The Yarlung Tsangpo powers the 510 megawatt Zangmu Hydropower Station. Gardelle et al (2013) identified this glacier as part of the West Nepal region, which experienced mass loss averaging -0.32 meter/year from 1999-2011. The changes of the Asejaguo Glacier are examined for the 1993 to 2018 period using Landsat imagery. Neckel et al (2014) examined changes in the surface elevation of the glaciers and found this region lost 0.37 m/year from 2003 to 2009.
In 1993 the glacier terminated in a small proglacial lake that is ~1 kilometer long at 4,900 m. At Point 1-2 there is limited exposed bedrock at 5,400-5,600 m, which is near the snowline; the head of the glacier is at 6,000 m. There is a prominent medial moraine that begins at 5,300 m where the north and south tributaries join. The greater width of the southern tributary indicates this is the large contributor. In 1994, the snowline is higher, at 5,500 m, but there is still only a small outcrop of bedrock at Point 2. By 2016 the proglacial lake has expanded to a length of over 2 km. At Point 1 and 2 there is a greatly expanded area of bedrock and the separation of a former tributary near Point 1 from the main glacier. In November 2018 there is fresh snowfall obscuring the exposed bedrock at Point 1 and 2. The retreat from 1993-2018 is 1.5 km, and the expanding proglacial lake is over 2.5 km long. The expanding bedrock areas in the 5,400-5,600 m range indicate the reason rise in snowline that has generated mass loss and ongoing retreat.
This article originally appeared on the American Geophysical Union blog From a Glacier’s Perspective.
In March 2019, lawmakers in Nepal proposed 17 amendments to the Safe and Peaceful Use of Nuclear and Radioactive Materials bill. Originally drafted almost a decade ago, the bill was presumably dead on arrival, but is now being resurrected in the wake of recently discovered uranium deposits in the Upper Mustang region of Nepal. The bill was officially re-introduced in December 2018, and in subsequent months a contentious debate has emerged on whether or not Nepal’s future should include nuclear power.
The nuclear bill would make uranium mining, enrichment, import, and export permissible and establish Nepal as a place where nuclear and radioactive substances could be stored. It would allow uranium enrichment facilities as well as nuclear research reactors (NRRs), which produce neutrons from enriched uranium to be used in medicine, industry, and other research, but do not generate power. To regulate the nuclear and radioactive power sector, the bill would allot non-transferable licenses and establish sanctions for technology misuse resulting in injury or death.
When proposed amendments came out in March, most excluded the word “nuclear” from the bill. Almost all lawmakers thought that nuclear power, if at all, should be addressed in a separate bill, rather than one regarding the use of radioactive materials. Many also opposed storage of nuclear weapons and nuclear power generation as a whole. For now, it is up to parliament to decide how the bill should be amended to address these concerns.
Back in 2014, a ground radiometric survey revealed a huge deposit of uranium ore in Nepal’s Upper Mustang region. Upper Mustang, formerly the elusive Kingdom of Lo, is tucked into the Himalayas right at Nepal’s northern border with Tibet. One of the most remote and isolated areas of the world, the entire Mustang region is home to around 13,000 people.
The Mustang region also accounts for more than 15 percent of Nepal’s glaciers, which feed the Kali Gandaki River. Despite the small population in its immediate surroundings, the largerGandaki River watershed provides water to some 40 million people.
Preliminary research, confirmed by the International Atomic Energy Agency (IAEA), suggests that the 10-kilometer-long, 3-kilometer-wide uranium deposit in Upper Mustang could be “of the highest grade.” Currently, however, there is no law governing uranium extraction or nuclear technology use in Nepal. In the absence of such legislation, the government has no means to carry out these activities, which can be exorbitantly expensive to undertake.
Proponents cite this gap as their motivation for endorsing the bill. For example, Nepal does not have the ability to import any nuclear-related technology necessary for treating cancer patients or to buy technology for nuclear power.
Giriraj Mani Pokharel, Nepal’s Minister of Education, Science, and Technology, is leading the charge for uranium extraction, production, and trade in Nepal. Under Pokharel’s direction, the ministry was responsible for introducing the nuclear bill in the first place. At an IAEA conference in December 2018, he said, “The goal of the country’s prosperity cannot be achieved without its development. So, opening a nuclear research center in Nepal is an urgent need.”
Though support for the bill is strong, several members of parliament, as well as Nepali people have pushed back equally as much, and for a number of reasons. In an opinion piece published on myRepública, Mahesh K. Maskey, the former ambassador of Nepal to China declared, “Uranium is a dirty and dangerous source of energy and radioisotopes. Dirty because it is detrimental not only to human and other life forms, but also to soil, water and air since its radioactive waste can remain for millions of years, bringing untold damage to the fragile environment of earth.”
His statement has relevance for the Upper Mustang region, its glaciers are perched on the roof of the world, forming a watershed that nourishes life and land all across Nepal, even reaching millions in China and India. To approve a uranium mining operation next door could put the entire Gandaki watershed at risk of contamination through radioactive pollution. In addition, Mustang’s uranium site is a mere 10 km from the Tibetan border, meaning Nepal could become responsible for imposing a radioactive hazard on people outside its borders.
Extractive industries are extremely expensive to undertake, especially if environmental protection is to be considered. The nuclear weapons potential of uranium is an additional complication. To offset the costs of mining uranium, Nepal would have to sell excess to other countries. At this prospect, Maskey surmised, “If we take a moment to think which country Nepal will approach to sell its uranium, we will realize how unthinkable such thought is.” Competition between the nuclear powers encircling Nepal could destabilize political relations, exacerbating the vulnerability of Nepal’s resources.
In an exhibition titled “Belonging, Transformation, and Ethnographic Predicaments in Nepal’s Himalaya,” a team of artists shared stories of their Himalayan experience through a collection of photographs. The exhibition was held at the University of British Columbia in Vancouver from February 1 to April 30. A closing reception, followed by a discussion of changing ethnographic practices, was hosted by the university April 23.
The exhibition highlighted many changes, which the artists—Yungdrung Tsewang, Tsering Gurung, Yeshi Gurung, Kory Thibeault, and Emily Amburgey—noticed while in Lower Mustang.
“The signs of transformation are hard to miss,” the artists wrote in their collective statement. The bulldozers and road construction teams, the newly constructed hotels and guesthouses, advertisements of hot showers and free Internet, the fallow agricultural lands, and the empty houses—these are the easily visible signs of transformations.
Less obvious, the artists pointed out, are “the class divisions that allow certain people to migrate while others stay behind, the decreasing numbers of practicing Buddhist monks, and the lack of spoken Tibetan among the younger generations.”
Embedded in the photographic depiction of transformations in this exhibition were questions of belonging and ethnographic predicaments. It is here that Emily Amburgey, whose photographs were not included in the exhibition, quietly shines. Amburgey said that she did not want the exhibit to just focus on the finished research products, “but to problematize the often complex and ongoing relationships between ethnographers and those they work with that make projects like these possible.”
Amburgey is a doctoral student of anthropology at UBC and her research focuses on labor migration and environmental change in Nepal’s Himalaya. The exhibition was a culmination of her different collaborative projects with friends from Nepal and the United States. Over the course of four months, Amburgey and Yungdrung Tsewang had come to the realization that the impacts of labor migration and climate change were radically transforming the human and nonhuman landscape in Mustang.
Tsewang was Amburgey’s research associate while she conducted fieldwork for her master’s program. During that time, together they organized a PhotoVoice project with the intention to work closely with the fellow artists Yeshi Gurung and Tshering Gurung, two women who are actively engaged in their community. PhotoVoice is a digital storytelling platform that seeks to inspire positive social change, enhancing the visibility of social issues through partnerships with community organizations using photographs as the medium.
Kory Thibeault, the fourth artist, is a friend from California, who came to help Amburgey shoot a documentary about her research. His photographs were taken during his stay in the region. The shared space of this exhibition highlighted the situated and overlapping perspectives of the different artists, expanding the notion of “belonging.”
When one belongs, the drastic consequences of ongoing processes become visible. Unpredictable weather patterns, extreme events, new diseases, and relocation of settlements, which might seem natural in harsh mountain environments for a passing visitor, become more than that to those who care to see. These are the new climate realities in the mountains.
“I believe that when Ladakhi elders talk about the fate of the glaciers of Ladakh, they are also reflecting on their own fate as their presence and influence decrease amid the dazzle of a new era,” Karine Gagne wrote in Caring for Glaciers.
The same could be said about Humla or Mustang or Khumbu, where the glaciers recede deep inside the valleys. The receding glaciers are entangled with the economic, socio-political, cultural, and generational changes. It is the dazzle of a new era that have now left those who remain in the villages looking toward the road.
The exhibition was curated by Rosaleen McAfee. It was co-sponsored by the Himalaya Program (funded by the Institute of Asian Research) and the Liu Institute for Global Issues at the School of Public Policy and Global Affairs at the University of British Columbia.
Following the closing reception on April 23, Emily Amburgey invited Mark Turin, an associate professor of anthropology at UBC, and I to join her for a conversation on the changing practices of ethnography and the position of an ethnographer in the Himalayan context. The conversation continues.
A photo essay version of this exhibition was published online at Himalaya: The Journal of the Association for Nepal and Himalayan Studies. It can be viewed here.
Nepal’s Government Considers Uranium Mining Legislation
From My República: “A hasty push for endorsement of the ‘nuclear bill’ in the parliament is being made amidst rumors of the discovery of uranium mines near trans-Himalayan terrain of Lo Mangthang of Mustang district. In fact, [the] Office of Investment Board’s website claims that ‘a large deposit of uranium has been discovered in Upper Mustang region of Nepal … spread over an area 10 km long and 3 km wide and could be of highest grade. These findings have also been confirmed by the International Atomic Energy Agency.’ The bill, tabled by Ministry of Education, Science, and Technology unabashedly grants permission to uranium mining, enrichment, and all steps of nuclear fuel cycle; import and export of uranium, plutonium, and its isotopes; and use [of] Nepal as transit for storage of the nuclear and radio-active substances.”
Retreating Glaciers Create … Clouds
From Nature: “Aeolian dusts serve as ice nucleating particles in mixed-phase clouds, and thereby alter the cloud properties and lifetime. Glacial outwash plains are thought to be a major dust source in cold, high latitudes. Due to the recent rapid and widespread retreat of glaciers, high-latitude dust emissions are projected to increase, especially in the Arctic region, which is highly sensitive to climate change. However, the potential contribution of high-latitude dusts to ice nucleation in Arctic low-level clouds is not well acknowledged. Here we show that glacial outwash sediments in Svalbard (a proxy for glacially sourced dusts) have a remarkably high ice nucleating ability under conditions relevant for mixed-phase cloud formation, as compared with typical mineral dusts.”
What Land Use Changes in Xinjiang, China Mean for Nearby Glaciers
From Sustainability: “[W]e analyzed the temporal-spatial variations of the characteristics of land use change in central Asia over the past two decades. This was conducted using four indicators (change rate, equilibrium extent, dynamic index, and transfer direction) and a multi-scale correlation analysis method, which explained the impact of recent environmental transformations on land use changes. The results indicated that the integrated dynamic degree of land use increased by 2.2% from 1995 to 2015. […] There were significant increases in cropland and water bodies from 1995 to 2005, while the amount of artificial land significantly increased from 2005 to 2015. The increased areas of cropland in Xinjiang were mainly converted from grassland and unused land from 1995 to 2015, while the artificial land increase was mainly a result of the conversion from cropland, grassland, and unused land. The area of cropland rapidly expanded in south Xinjiang, which has led to centroid position to move cropland in Xinjiang in a southwest direction. Economic development and the rapid growth of population size are the main factors responsible for the cropland increases in Xinjiang. Runoff variations have a key impact on cropland changes at the river basin scale, as seen in three typical river basins.”
Bridging Traditional Knowledge and Satellite Images in Bolivia
From Regional Environmental Change: “In the Andes, indigenous pastoral communities are confronting new challenges in managing mountain peatland pastures, locally called bofedales. Assessing land cover change using satellite images, vegetation survey, and local knowledge (i.e., traditional ecological knowledge) reveals the multi-faceted socio-ecological dimensions of bofedal change in Sajama National Park (PNS), Bolivia. Here, we present results from focus groups held in 2016 and 2017 to learn about the local knowledge of bofedales in five Aymara communities in PNS. Land cover maps, created from Landsat satellite imagery, provided a baseline reference of the decadal change of bofedales (1986, 1996, 2006, and 2016) and were field verified with vegetation sampling. At the park level, the land cover maps show a reduction of healthy bofedales (i.e., Juncaceae dominated peatland) cover from 33.8 km2 in 1986 to 21.7 km2 in 2016, and an increase in dry mixed grasses (e.g., Poaceae dominated land cover) from 5.1 km2 (1986) to 20.3 km2 (2016). Locals identify climate change, lack of irrigation, difficulty in water access, and loss of communal water management practices as key bofedal management challenges. Local improvement of bofedales was found in one community due to community-based irrigation efforts. Bridging knowledge of mountain land cover change helps to articulate the socio-ecological dimensions that influence local decision-making regarding bofedal management, and consideration of local actions that may be strengthened to support the sustainability of bofedales for local livelihoods in the context of climate change in the Andes.”
Pleistocene and Holocene Cirque Glaciation in the Western United States
From Nature: “Our [glacier chronology] demonstrates that each of the moraines originally interpreted as Neoglacial was deposited during the latest Pleistocene to earliest Holocene (between ~15 and 9 ka), indicating that, with the exception of some isolated locations, cirque glaciers in the western U.S. did not extend beyond their LIA limits during much, if not all, of the Holocene.”
“Glacial lake outburst floods (GLOFs) pose a significant, climate change-related risk to the Mt. Everest region of Nepal. Given the existence of this imminent threat to mountain communities, understanding how people perceive the risk of GLOFs, as well as what factors influence this perception, is crucial for development of local climate change adaptation policies. A recent study, published in Natural Hazards, finds that GLOF risk perception in Nepal is linked to a variety of socioeconomic and cultural factors.”
“Amid the tropical Andes of Peru lies the Cordillera Blanca mountains, home to more tropical glaciers than anywhere else on Earth. This range provides water to some 95 million people. Rising temperatures over the last several decades, however, mean its once abundant glaciers are vanishing rapidly. That’s impacting the water supply of downstream communities, which are becoming increasingly dependent on soil moisture.
In an innovative study published in the journal Remote Sensing of Environment, researchers used drones to obtain high-resolution images of the valleys left behind as Cordillera Blanca’s glaciers recede. As the drones pass over these “proglacial valleys,” they can produce highly accurate maps of the soil moisture within the fields, rivers, wetlands, and meadows below.”
Heavy Snowfall and the Threat of Avalanches in Switzerland
“In January, officials dropped a series of controlled explosives to set off avalanches on mountains near the Moiry Glacier in southern Switzerland due to an increased amount of snowfall during the month. Communities are directed to stay inside (or preferably go into a basement) while the avalanches are triggered and close all shutters. Controlled avalanches are intended to reduce the severity of an avalanche as well as collateral debris from an avalanche, making it safer for adventurers to romp around the backcountry. The use of explosives to mitigate avalanche risk is used throughout many mountain communities, especially when areas experience above average snowfall.”
The Tamang community are an indigenous group in Nepal that have depended on cattle rearing for the last three centuries. Located in the northernmost part of central Nepal, herding is a livelihood that has long held a significant role in the culture of this rural, indigenous Himalayan community. Shepherding among the Tamang, however, has dwindled over the last few decades as younger generations are becoming less likely to take up the tradition passed down from older generations.
Manchhiring Tamang’s documentary “A Day in the Life of a Himalayan Shepherd” beautifully captures the vast Himalayan landscape and sheepherding practices of the Tamang valley. The film recently debuted at the 12th annual Colony Short Film Festival in Marietta, Ohio, where it was runner up in the Best Documentary category.
The short film follows 45-year-old Khariman Tamang, a shepherd following in the footsteps of his father and grandfather. Despite the harsh climate and physical challenges of caring for his sheep, he takes great pride in the rich cultural tradition within the Tamang community.
Khariman lives in Sertung, a stunning yet isolated region located in the upper Dhading district in central Nepal. He provides for his wife, two sons, and daughter through sheep herding.
Shepherds in the region must leave their families for six months of the year to move their herds to colder climates. Tamang herders roam the valley with their flocks in constant search of ideal weather conditions that produces abundant grasses for feeding. Shepherds sometimes visit their families between seasons and during special holidays and festivals.
Sheep provide the people of Tamang with food, dairy products for medicinal and cosmetic products, and wool for clothing and other necessities. Wool plays an essential role in Tamang culture. It is often used for making traditional clothing, beds, blankets, carpets, and rugs. Family members and neighbors borrow and exchange woolen products, bolstering livelihoods and enriching connections among the Tamang community.
GlacierHub met with Manchhiring Tamang, who was born and raised in the Tamang village depicted in the film. He has worked as a research journalist with a focus on the indigenous groups of Nepal and tourism. His father and grandfather were also sheep herders in the valley.
Manchhiring, who now lives with his family in New York City, aims to show people the beauty of the culture and traditions of the Tamang community in Nepal. This film gives viewers a glimpse into the lifestyle of this age-old tradition which has seen a major shift in recent years. He spoke to us about how the sheep herding practice has changed over time with new generations.
“This profession amongst this modest community is on the verge of extinction, and the older generations are forced to think whether this will be the last generation involved in this job sector,” said Manchhiring.
Kathryn March, an anthropologist at Cornell University familiar with the Tamang people of Nepal, told GlacierHub that as climate patterns shift and seasonal precipitation becomes more erratic, traditional knowledge becomes increasingly unreliable. The timing of funerals, weddings, and other cultural rituals is thrown into uncertainty by climate change.
March added that working-age men in particular are increasingly moving out to Gulf countries and Southeast Asia. “The previous household economic strategies of trying to have multiple sources of income, from agriculture and herding and trade or seasonal employment, have been radically transformed into widespread dependence on remittances from outside wage labor, ” she said.
Manchhiring hopes to preserve the traditional practices of the Tamang people through “A Day in the Life of a Himalayan Shepherd.” He said: “I want people to know the hardness and struggle of country people like my uncle who are struggling to keep up their ages old tradition, struggle of dilemma as to whether to abandon their tradition or to keep it.”
Glacial lake outburst floods (GLOFs) pose a significant, climate change-related risk to the Mt. Everest region of Nepal. Given the existence of this imminent threat to mountain communities, understanding how people perceive the risk of GLOFs, as well as what factors influence this perception, is crucial for development of local climate change adaptation policies. A recent study, published in Natural Hazards, finds that GLOF risk perception in Nepal is linked to a variety of socioeconomic and cultural factors.
Sonam Sherpa, lead author of the study and PhD candidate at Arizona State University, spoke to GlacierHub about the study’s primary objectives. She and the other researchers aimed to “capture the complex natural-social system interactions of cryospheric hazards in the Nepal Himalaya.” She further emphasized the importance of understanding how communities, “perceive the risk coming from glacial lake outburst flood, as perceptions can influence their actions, beliefs, and responses to natural hazards and associated risks.”
GLOFs occur when a lake’s natural barrier, usually a moraine, suddenly fails. The trigger can be a natural disruption, like a landslide, earthquake, or avalanche, or simply the buildup of excess water pressure from increased melt. GLOFs result in a rapid discharge of a lake’s water, inundating the downstream ecosystem with little to no warning. These events are destructive and endanger the lives and livelihoods of communities downstream.
While scientists are clear about the threats posed by GLOFs, downstream communities often ignore or underestimate the potential impact floods could cause to life and livelihoods. So what are the factors contributing to how communities perceive this risk, and what factors influence their opinions?
The researchers conducted a survey of 138 households across nine villages within the Mt. Everest region. The survey elicited self-reported demographic information, such as age, gender, and sources of income. It also assessed risk perception regarding climate change, natural hazards, and hazards specific to regions with glaciers.
One survey question asked locals to rank various hazards “based on their likelihood and potential to damage.” Twenty seven percent of people ranked earthquakes first, while 23 percent put glacial floods first.
The researchers noted the 7.4 magnitude Gorkha earthquake in Nepal one year before, and attributed this result to cognitive availability, whereby recent or common events are more readily recalled than rare events. Sherpa, who is from the Khumbu area within the Mt. Everest region, even recalled her own fear that a glacial lake outburst flood would occur following the Gorkha earthquake.
In addition, the researchers found that rapid-onset events, namely earthquakes and GLOFs, were consistently ranked much higher than slow-onset impacts of climate change, such as changing weather patterns and water availability. GLOFs and earthquakes, though infrequent, occur rapidly and have catastrophic impacts, so people fear these events more.
Experience was a huge influence on risk perception. Both among individuals and communities that had previously experienced a GLOF event, the researchers observed a direct correlation between their experience and their perception of GLOFs as a critical threat.
When responses were analyzed by demographic, however, there was increased variation in the results. For example, young people perceived GLOFs as a greater risk than older people. The researchers surmised that media exposure coupled with more sources of information on climate change among the younger generation could explain this result.
In search of more factors influencing risk perception, the researchers chose two of the nine villages to compare—Dingboche and Monjo. The two villages are located in different altitudinal zones, Monjo at 2,835 meters and Dingboche at 4,350 m, are considered high-risk areas for GLOFs. Residents of Monjo perceived the most risk from earthquake, then unseasonal rainfall, and finally drought, while residents of Dingboche ranked earthquake, GLOF, then wind in order of risk.
“As a local Sherpa from Khumbu (the Mt. Everest region) myself, I had a little hint with regard to how one would perceive risk from glacial hazard based on spatial proximity,” said Sherpa. “It was surprising to see that in the data showed a similar result as well.”
The study identifies several reasons for the two villages’ variety in rankings. First is their geographical location. At its higher altitude, Dingboche is in closer proximity than Monjo to glacial lakes. The Dingboche village sits directly below Imja Lake, a heavily studied glacial lake which scientists categorize as a moderate to critical GLOF risk.
Geographical location further influences the primary source of livelihoods. Villages dependent on tourism are more likely to have access to have information about GLOF risks. Dingboche is heavily dependent on tourism because its altitude is too high to support much agriculture. In contrast, Monjo relies equally on the tourism and agriculture industries.
In 2016, Imja Lake underwent emergency remediation work to lower its water levels by 3.5 m. Following the project’s completion, perceived risk of GLOFs decreased in Monjo, but not in Dingboche. For Monjo, the remediation was a cognitive fix, but not for Dingboche. The project lowered the probability of a GLOF occurring, but as the closest village to Imja Lake, residents of Dingboche continued to perceive it as a critical threat to their community. Sherpa noted the remediation’s function as a cognitive fix as one of the study’s most interesting results, following the finding that proximity was a huge influencing factor on risk perception.
“I went through an emotional roller coaster thinking how rapid the changes are, in the glacial system and how it could impact my community, but at the same time how, very little is understood with regard to what’s happening in this biophysical system,” said Sherpa. Through this risk perception analysis, the researchers aimed to emphasize the necessity of including locals in the development of climate change adaptation policies.
Accurate scientific information is critical, but it is equally as important to communicate potential hazards properly so communities truly understand the risks they face. Only then will scientists, government, and local communities truly be able to work together to create a comprehensive plan to mitigate and adapt to the risks they face.
From Earth-Science Reviews: “This paper comprehensively reviews the current status and recent changes of the cryosphere (e.g., glacier, snow cover, and frozen ground) in the TP from the perspectives of observations and simulations. Because of enhanced climate warming in the TP, a large portion of glaciers have experienced significant retreat since the 1960s, with obvious regional differences. The retreat is the smallest in the TP interior, and gradually increases towards the edges.”
From Nature: “Here we find that subglacially produced methane is rapidly driven to the ice margin by the efficient drainage system of a subglacial catchment of the Greenland ice sheet…We show that subglacial hydrology is crucial for controlling methane fluxes from the ice sheet…Overall, our results indicate that ice sheets overlie extensive, biologically active methanogenic wetlands and that high rates of methane export to the atmosphere can occur via efficient subglacial drainage pathways. Our findings suggest that such environments have been previously underappreciated and should be considered in Earth’s methane budget.”
From Landslides: “On April 20, 2017, a flood from the Barun River, Makalu-Barun National Park, eastern Nepal formed a 2–3-km-long lake at its confluence with the Arun River as a result of blockage by debris. Although the lake drained spontaneously the next day, it caused nationwide concern and triggered emergency responses…This study highlights the importance of conducting integrated field studies of recent catastrophic events as soon as possible after they occur, in order to best understand the complexity of their triggering mechanisms, resultant impacts, and risk reduction management options.”
Sublimation, the process by which a solid changes phase to gas, is a largely unquantified component of glacier mass loss worldwide. A study on Nepal’s Yala glacier, recently published in Frontiers In Earth Science, quantified the glacier’s loss of ice to the atmosphere during the 2016-2017 winter. Researchers found approximately 21 percent of Yala’s annual snowfall was returned to the atmosphere via sublimation, a rate higher than most glaciers on Earth’s tallest mountain ranges.
Like classroom demonstrations with dry ice, sublimation can occur from a static surface. Snow sublimation is the loss of water from the snowpack directly to the atmosphere. Though Yala is one of the world’s most studied glaciers, a complete understanding of water balance and glacier mass has been limited. In addition, complex terrain and dynamic conditions often inhibit models from accurately estimating sublimation.
The process to measure the rate of sublimation is complicated: sublimation varies based on the time of year, hour of the day, cloud cover, complex terrain features, altitude, and specific atmospheric conditions like humidity and wind speed. Even in a static environment, these components are difficult to measure. Add dynamic environmental factors like drifting and blowing snow, ice that melts and refreezes (skewing energy balance calculations), and remote fixed instruments that rise and fall with the glacier itself, and you get a vague idea of the quantification problem faced by scientists.
Researchers utilize two primary methods to measure sublimation: the gravimetric method, which continuously monitors the weight at a specific part of the snowpack, and the eddy covariance method, a process of direct observation to measure and calculate atmospheric factors. The gravimetric method can incorrectly interpret wind-induced erosion of the snowpack as sublimation. The researchers, which were comprised of a team from Utrecht University and the International Centre for Integrated Mountain Development, were able to measure turbulent fluxes at Yala’s surface using the latter technique. Turbulent fluxes act on frozen water molecules the same way wind might affect leaves scattered on a surface; some are lifted and become airborne, while others remain grounded, depending on the wind strength, direction, and location. Through extensive and careful post-processing of the water vapor, air temperature, and vertical wind, the research team was able to accurately estimate sublimation.
Out of the myriad components affecting sublimation, the team condensed Yala’s sublimation rate into two primary determinants, wind speed and humidity, which vary depending on the time of year and day. Daily sublimation rates were separated into humid days and non-humid days. Less sublimation occurs on humid days, due to colder surface temperatures and a weaker vapor pressure gradient. When humidity is low, winds increase, resulting in a well-mixed atmospheric layer above the surface and a vapor pressure gradient ideal for sublimation. Sublimation varies greatly from location to location on the glacier.
The project required two trips: one to install equipment and a second to retrieve the data. Emmy Stigter, a doctoral student at the University of Utrecht in the Netherlands and principal author of the study, led the research team. “The fieldwork involves quite some hiking and a lot of logistical challenges,” she told GlacierHub. Yala is a four-day hike from the start of the Langtang Valley, which is a day’s drive from Kathmandu. The instruments required so much energy to power that the team had to lug a car battery up the glacier to ensure it would have sufficient energy to run during the research. Though the equipment was in place all winter, a data card was corrupted, limiting some of the team’s observations to just over a month in autumn.
During the 32-day study period, which occurred from October to November 2016, Yala lost 32 millimeters of water equivalent. This represents a significant share of the glacier’s net loss during the period (70mm). Yala’s one millimeter per day rate of sublimation is a pace higher than the Swiss Alps, Colorado Rocky Mountains, and Spain’s Sierra Madre. Due to the low atmospheric pressure, sublimation is most prolific at high altitudes, like that of the Himalaya. Only Kilimanjaro and the Andean peaks exhibit comparable rates of sublimation, according to the authors.
The researchers found that sublimation rates are highest in November and December and peak around one o’clock in the afternoon. Sublimation rates also differed depending on wind at the locations on the 1.5-square kilometer glacier; the faster the wind, the faster the rate of sublimation. Stigter’s team observed that rates were 1.7 times higher on ridges and .8 times lower at the bottom of the glacier.
Blowing snow, which was not accounted for in this study, may be a consequential factor leading to underestimation of mass loss to sublimation. Suspended particles sublimate on an order several times greater than the surface sublimation, as there is more ventilation and supply of dry air. One study showed that up to 30 percent of annual snowfall was removed in the Canadian prairie and Alaska due to blowing snow sublimation, while Antarctica lost up to 85 percent of its precipitation. Stigter is currently involved in a new study quantifying sublimation during wind-induced snow transport events.
Park Enlists Citizens to Track Changes in Teton Glaciers
From U.S. News: “The project aligns with one of Grand Teton’s fundamental duties, keeping tabs on its natural resources. Estimates vary, but with global temperatures increasing some studies suggest many glaciers could disappear within the next few decades.”
Fracturing Glacier Revealed by Ambient Seismic Noise
From AGU 100: “Here we installed a seismic network at a series of challenging high‐altitude sites on a glacier in Nepal. Our results show that the diurnal air temperature modulates the glacial seismic noise. The exposed surface of the glacier experiences thermal contraction when the glacier cools, whereas the areas that are insulated with thick debris do not suffer such thermal stress.”
From Science Direct: “Here, we use a multi-proxy approach that combines proglacial lake sediment analysis, cosmogenic nuclide surface-exposure dating (in situ10Be and 14C), and radiocarbon dating of recently ice-entombed moss to generate a centennial-scale record of Holocene GIC fluctuations in southwestern Greenland.”
Read more about holocene mountain glacier history here.
From Phys.org: “In the last few years, the Vavilov Ice Cap in the Russian High Arctic has dramatically accelerated, sliding as much as 82 feet a day in 2015, according to a new multi-national, multi-institute study led by CIRES fellow Mike Willis, an assistant professor of Geology at CU Boulder.”
Glacier Retreat Drives Reduction in Italian Hydropower
From Applied Energy: “We assess the impacts of nine climate-change scenarios on the hydrological regime and on hydropower production of forty-two glacierized basins across the Italian Alps, assumed exemplary of similar systems in other glacierized contexts.”
Read more about hydropower in the Italian Alps here.
Debris-Covered Glaciers in Nepal
From Frontiers in Earth Science: “We present measurements collected between 26 September and 12 October 2016 from an eddy correlation system installed on the debris-covered Lirung Glacier in Nepal during the transition between monsoon and post-monsoon. Our observations suggest that surface energy losses through turbulent fluxes reduce the positive net radiative fluxes during daylight hours between 10 and 100%, and even lead to a net negative surface energy balance after noon.”