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.