Lessons From Peru to Nepal
Glacial Lake Outburst Floods: “The Threat From Above”November 18, 2011 By Kate Diamond
“We have never experienced so many potentially dangerous lakes in such a short period of time,” said Alton Byers of The Mountain Institute (TMI) during a roundtable discussion on glacial melt, glacial lakes, and downstream consequences at the Wilson Center on October 26. “There have always been glacial lake outburst floods,” said Byers. What has changed is how quickly these lakes now grow. “Suddenly, you wake up in the morning, and now there are hundreds and hundreds of these lakes above you – the threat from above,” he said.
Nepal’s Fastest Growing Glacial Lake
The Imja Glacier in Nepal has been receding since the 1960s, making Imja Lake the fastest growing lake in the country, if not the entire Hindu Kush Himalayas, said Byers in a short film produced by TMI about the group’s recent expedition to the region (watch below). The lake is now “more than a square kilometer in size, has more than 35 million cubic meters of water, and continues to grow at an alarming 35 meters per year,” he said.
The lake’s terminal moraine – the buildup of glacial debris that acts as a retaining wall holding the lake waters back – is all that keeps Imja from flooding the valley below, home to a number of Sherpa communities and the starting point for many climbers scaling Mount Everest.
When these moraines break, the result is a glacial lake outburst flood (or GLOF). And “these aren’t floods in the normal sense,” said Gabriel Campbell. “These are floods that carry boulders the size of houses,” because of all the debris that gets lodged in glaciers.
Critical Need for Research
It is tempting to say that what is happening at Imja Lake is representative of the thousands of glacial lakes believed to exist throughout the Himalayas, but the fact is that “at this point in time, we don’t really know that much about these lakes,” or how to control them, said Byers.
Glacial melting “is an extraordinarily complicated story,” said ClimateWire’s Lisa Friedman, who joined the Imja expedition for part of the trip. There is no “clear understanding yet of how fast glaciers are melting, of where they’re melting, of whether greenhouse gases or black carbon soot is primarily responsible.”
There is considerable disagreement over how many glacial lakes are even in the Himalayas, TMI Executive Director Andrew Taber added, simply because of how prohibitively remote their locations often are. Byers explained that it can take as many as 10 days, plus semi-technical climbing, to reach these places, and even then some glaciers still aren’t accessible. The Siachen Glacier, for instance, has the distinction of being the world’s highest battleground (India and Pakistan have had troops stationed on the glacier since 1984).
And yet understanding what is happening not just at Imja, but throughout the Himalayas, has continental implications. Himalayan glaciers feed nine of Asia’s largest rivers: the Yellow, Yangtze, Mekong, Salween, Indus, Ganges, Brahmaputra, Syr Darya, and Amu Darya. Those rivers, in turn, feed some of Asia’s largest population centers. The sheer number of people who depend on these rivers mean that even minor changes in glaciers’ sizes can have exponentially huge impacts downstream.
Adapting Lessons Learned from Peru
The Mountain Institute’s expedition was aimed at bringing lessons learned about managing glacial change from Peru to Nepal. Peru is home to 70 percent of the world’s tropical glaciers, but those glaciers are melting so quickly that some have predicted within 15 years, they could disappear entirely.
Peru has been working to mitigate the threat of glacial melt since 1941, when a GLOF killed thousands and devastated the capital of Ancash, said César Portocarrero of the Peruvian National Water Authority (also a member of the expedition to Imja). At first, risk management meant simply diverting water from glacial lakes to lower the risk of GLOFs. Over time, though, and with community input, that strategy has expanded to include more comprehensive resource management, so that water being diverted from lakes can be captured and put to use downstream.
Just as Peru’s mitigation work is a reflection of local needs, finding a long-term solution for Imja Lake will depend on local involvement. “When you think about science, and when you think about change, there’s something to be said for more demand driven approaches,” Taber said. “Working with local people…is more likely to lead to solutions and answers that will actually be picked up.”
And yet, Byers said, local people have often been marginalized in research on glacial melt in the Himalayas. “There’s been 30 years of research on this and other lakes and yet no researcher has ever involved them in their research, and they had no idea what the results were,” he said. The TMI expedition made a point of incorporating local residents throughout the process.
Acting in Spite of Uncertainty
Portocarrero said that convincing people of the need for risk management can be difficult. “Around the world, it seems that people don’t want to work in risk management because we don’t have tangible results,” said Portocarrero. And when risk is mired in uncertainty – as it is in the Himalayas – getting people to invest in risk management becomes even harder.
Portocarrero warned it might take a decade or more for people downstream to realize Imja and other glacial lakes pose a serious danger and take action. “But the big question is,” he added, “are we going to wait 10 years to see the real danger?”
“Climate change is a threat multiplier for instability in fragile regions of the world,” said Goodman. Considering those stakes, uncertainty “can’t stop you from making smart decisions based on today’s information for adaptation.”
Sources: The Diplomat, Global Security, The Guardian, The Mountain Institute, NASA, U.S. Geological Survey, The Washington Post.
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