Glaciers on Nepal’s Imja Tse (Island Peak) in the Himalayas have melted at an average rate of almost 10 meters per year over the past several decades, during which time residents of Imja Tse Valley below have literally watched the residual waters create an entirely new lake. The Imja Tsho (Imja Lake) first began collecting glacial meltwater in the 1960s, when it had a surface area of approximately 49 square kilometers. By 2007, it had grown to 945 square kilometers, an almost 2,000% increase. The aggressive rate of growth has residents and scientists worried about the threat of glacial lake outburst floods (GLOFs).
The Himalayas are often considered the earth’s “third pole,” given that they contain more ice than anywhere else in the world besides the ice caps in the Arctic and Antarctica. Glacial retreat in this region is also happening faster than anywhere else in the world. According to a study released earlier this year by the Chinese Academy of Sciences, glaciers on the Tibetan Plateau have shrunk by 15 percent in the last three decades to 43,000 square kilometers. The melt has been almost unanimously attributed to human-induced climate change.
In recent years, some organizations have found themselves in hot water for overstating the degree of melting at the Himalayan glaciers. In 2007, the United Nations’ Intergovernmental Panel on Climate Change, a scientific body made up of thousands of scientists and researchers, issued a report that claimed Himalayan glaciers could completely melt away by 2035. Three years later, IPCC officials issued a statement that said those original estimates were unfounded. (An op-ed appearing in April in Scientific American pointed out the seriousness of such overstatements.) And yet, despite the “Himalayan Blunder,” scientists still believe that by the time global temperatures increase by just 2 degrees Celsius, more than half of the Himalayan glaciers will have vanished.
GLOFs like the ones threatening the Imja Tse Valley are an increasing concern worldwide, and the Himalayas, with so much melting ice, are particularly at risk. Glacial lakes are not a new or human-induced phenomenon, however conditions become unstable when these lakes form quickly in cracks and valleys previously covered in ice. It is often unclear whether the walls of the lakes are made of rock or melting ice, which heightens the risk of flooding and landslides.
Many residents of the towns and villages scattered on the foothills of Himalayan glaciers, have already fallen victim to floods, avalanches, and mudslides caused by GLOFs. These disasters can result in loss of life and property, damaging essential infrastructure, destroying crops and crop land itself, and sometimes laying waste to entire villages, leaving only inhospitable rock and mud behind.
For these reasons, there has been increasing attention to monitoring new and expanding glacial lakes in the region. In 2011, the Mountain Institute organized a team of 30 scientists from around the globe to study the Imja Tsho, and concluded that the lake does, in fact, pose a potential threat to local communities. They estimated that melting ice under the moraine could trigger a huge flood, and that meltwater could seep through the hills around the lake, potentially causing a hill to collapse. They also warned that as melting continues, ice avalanches could tumble into the lake, causing a giant wave to deluge downstream communities.
Last year, scientists from the High Mountain Glacier Watershed Program returned to Imja to discuss with village leaders the risks the lake poses and come up with a plan of action. They determined that there were three options: accepting the risk of a possible GLOF; relocating lodges and other structures to higher elevations to avoid flood damage; or an engineering solution, “such as siphoning or controlled drainage canals.” They emphasized the importance of letting the community decide, as opposed to outside groups or government.
But many residents are simply fed up with all of the warnings and scientific predictions. “We’ve been living in the shadow of this lake for so long now,” Ang Nima Sherpa, a local businessman told the Guardian in 2011. “The only thing I am interested in hearing about now is whether they can get us a hydroelectric plant out of that lake.”