Namdu Sherpa picked potatoes as a girl in Namche Bazaar, the only economy in her village before Mount Everest-bound adventurers made a habit of trekking through with their Gore-Tex jackets and titanium walking poles. Almost overnight, the 75-year-old great-grandmother said, her small trading post in Nepal's Khumbu Valley transformed into a bustling tourist hub of lodges and cyber cafes.
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| Namdu Sherpa, 75, says villagers in her town of Namche Bazaar see changes on the mountain, but don't understand them. Photo by Lisa Friedman. |
Nodding toward her gleaming Samsung refrigerator and microwave, Namdu Sherpa said life has changed dramatically from the days of tending crops and cooking over firewood. Through the years, though, one thing remained constant: the majestic snow-capped Himalayan mountains. Until recently, that is.
"The mountains used to be white. Now, the mountains don't seem so white. It's all rocks," she said, looking out her kitchen window at the cloud-covered peaks. "We don't know exactly what's happening."
Neither, it seems, do scientists. There is widespread acknowledgement that the snow cover in the Himalayan mountain range is declining, and that many glaciers are retreating at a rapid rate. But everything else -- from where melt is occurring to how fast, how much melt contributes to downstream water use, and even to what extent greenhouse gas emissions play a role compared to soot -- is being answered at a glacial pace.
The difficulty in obtaining solid data on the mountain range is rooted in both the area's remoteness and regional political rancor. Compounding the uncertainty is doubt about the credibility of the Intergovernmental Panel on Climate Change, which had stated in 2007, wrongly, that Himalayan glaciers could melt by 2035. Scientists say the doomsday scenario error did lasting damage to popular understanding of the Himalayas. It also underscored how tenuous their grasp on the region really is.
"The knowledge gap is large," said Richard Armstrong, a glaciologist and senior research scientist at the National Snow and Ice Data Center in Boulder, Colo. Armstrong and dozens of other scientists met in Washington, D.C., this month with the National Academy of Sciences to begin to tease out the answers to some of the most vexing questions.
Scientists note that the Himalayan glaciers are sensitive to summer warming because both accumulation and ablation, or melting, primarily occur during the summer monsoon season. That means small increases in summer temperatures accelerate the melt while at the same time causing precipitation to fall as rain, which flows away, rather than snow.
"Glaciers are a dynamic system, sort of a conveyor belt of ice from a higher elevation to a lower elevation," each part with its own individual behavior, he said. If everything is going well for a glacier, the mass it loses by seasonal melts at lower elevations is replaced by snowfall at higher elevations -- which then is packed down into ice and and carries its mass downhill over decades.
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| Nepal's Khumbu Glacier, one of the most visited in the Himalayas, is retreating at an average speed of 20 meters per year. But scientists say it's impossible to generalize about glacier melt in the Himalayas, where some are retreating faster than others and some are even growing. Photo courtesy of Flickr. |
Particularly in the eastern Himalayas, glaciers in lower elevations "are definitely seeing a warming," Armstrong said, while those above 18,000 feet appear far more resilient. Meanwhile, contrasting patterns of growth are evident in the western Himalayas among some 230 glaciers.
Armstrong rattled off a handful of hyperbolic statements that have made their way into the mass media -- like that glaciers are melting faster in the Himalayas than anywhere else in the world, or that glacier melt will lead to catastrophic floods throughout Asia. There is little or no scientific evidence for some of these claims, he argues.
While Armstrong chalks up exaggerations to the mysterious romanticisms that people apply to glaciers, he worries that those claims ultimately do a disservice to grasping the damage that the retreat of lower-elevation glaciers in the eastern Himalayan region will have on the wider region's water resources.
"If a glacier can melt fast enough to cause a flood in Bangladesh, we're in bigger trouble than we thought," he said. Like other outsized claims, he said, "it's an example where there's not a lot of good data available, so if there's some emotional trigger ... people can say whatever hits them emotionally, and you can't prove them wrong."
But understanding the area of what is called the Hindu Kush-Himalayan region is crucial. The remote mountain region encompasses about 15,000 glaciers -- sometimes referred to as the planet's third pole because it is the largest concentration outside of the Arctic and Antarctic -- and sweeps through Pakistan, India, China, Nepal and Bhutan. The melted snow becomes the mother of headwaters for Asia's seven largest rivers, which in turn sustain some 1.5 billion people.
While new research is showing that not all glacier-fed rivers are as dependent on melt as others, the Indus River is heavily fed by the Himalayan snow and ice melt (see related story). In Pakistan, the Indus and its tributaries keep more than 80 percent of the country's agricultural land fertile. One U.S. Agency for International Development (USAID) report predicts Pakistan could face a "terrifying" 30 to 40 percent drop in Indus River Basin flows over the coming century.
Some scientists predict the Ganges River could drop off by two-thirds, affecting the more than 400 million people who depend on it. The Brahmaputra River flows through China and India into the Bay of Bengal in Bangladesh. If that river dries up, so will water availability for the millions of people along the Brahmaputra in Assam and Bangladesh.
In the short term, the melting glaciers mean increased risk of mudslides, erosion and flooding. Countries like Bhutan and Nepal are particularly at risk of glacier lake outburst floods, or GLOFs, that threaten to destroy entire villages.
"All over the world, the cryosphere is being affected, but in this region especially you see the huge populations that are being sustained by agriculture," said Syed Iqbal Hasnain, a distinguished visiting fellow at the Stimson Center and chairman of the Glacier and Climate Change Commission established by the state government of Sikkim in India.
"The global community has to come forward and do something," he said. "It's critical, because of the huge populations in this entire region which are directly dependent on this water."
The physical act of studying Himalayan glacier melt is no easy task. Basic field measurements present a formidable challenge, since even the most rugged of researchers, able to hike for weeks through pine forests and Sherpa villages at high altitudes, can access only lower-elevation glaciers.
Recently, a group of scientists led by the Mountain Institute and funded by USAID trekked for 18 days through Nepal's Khumbu Valley merely to observe the severely threatened Imja Lake. Just arriving at the growing glacier lake took eight days of uphill hiking, with time built in to adjust to the 5,000-meter climb.
Dirk Hoffmann, a geographer with the Bolivian Mountain Institute who was on the trek, said getting to Imja -- still one of Nepal's most accessible and most studied glacier lakes -- put the difficulties of research in Bolivia's Apolobamba Mountain Range into perspective.
"The Apolobamba is little-explored, and the least accessible mountain range in the Andes. But that is relative, as I learned here in the Himalayas," Hoffmann said.
And the dangers have not been limited to exhaustion and altitude sickness.
Nepal, while currently peaceful, is recovering from a decadelong civil war. Teiji Watanabe, a professor of environmental science at Hokkaido University in Japan who has studied Imja Lake for more than three decades, recalled how the perils of research became almost too great in the 1990s. Working in a lodge caught between the Nepalese police forces headquarters and Maoist insurgents, Watanabe said he still remembers shouting "Japanese! Scientist!" every time he raced to the outhouse.
Meanwhile, the Siachen Glacier in Kashmir -- sometimes called the highest battleground on Earth at 20,000 feet -- feeds Pakistan's Indus River, but is "impossible to study," said Saleem Ali, a professor of environmental studies at the University of Vermont. India and Pakistan maintain a large military presence in the region, and only a select group of Indian scientists has ever been able to conduct field research on the glacier.
Perhaps not surprisingly, cooperation in a region so rife with conflict is far from easy. Daan Boom, a knowledge management specialist with the International Centre for Integrated Mountain Development (ICIMOD) in Kathmandu, calls the lack of regional cooperation one of the greatest challenges in addressing the impacts of hydrological changes in the Himalayas.
"There's not enough data to predict what's going on in the mountains, and obtaining data is difficult," he said. "Regional cooperation is not optimal for data sharing."
That's slowly starting to change, and activists are eyeing a major ministerial-level conference next month in Bhutan as a place where the region could finally start to make strides in working together to promote Himalayan health. The Climate Summit for a Living Himalayas, as it is being called, is for the first time bringing together regional governments to try to develop a 10-year blueprint for climate change adaptation in the region. Madhav Karki, deputy director-general of ICIMOD, called the Bhutan summit "a truly unique approach," and said he hoped such a road map could be replicated elsewhere.
Yet even here the divisions are visible. Bhutan, Nepal, India and Bangladesh are co-hosting the event, and so far, there is little evidence of Pakistan or China's involvement. Organizers officially say the omission is simply geographic -- the eastern Himalayas require urgent action -- but activists quietly acknowledge that regional politics play a part, as well.
In the meantime, all people in countries like Nepal can do is watch as the stunning scenery outside their homes is perhaps forever altered.
"We used to have snow -- lots of snow. Now we see less snow, and even when it does snow, because the land is warmer, it melts. The glaciers are also melting. That we know," said Ang Phurba Sherpa, 69, the former head of Namche Bazaar's governing board. But, he said, despite the several workshops on global warming that local activists have sponsored, local people are not sure what they can do to stop the changes they see around them.
"We know that change is in the mountain," Ang Phurba Sherpa said. "The glacier is so much changed. We have town meetings about global warming, but the only thing they can do is advise the people and make them aware."
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From the Andes to the Himalayas, scientists are starting to question exactly how much glaciers contribute to river water used downstream for drinking and irrigation. The answers could turn the conventional wisdom about glacier melt on its head.
A growing number of studies based on satellite data and stream chemistry analyses have found that far less surface water comes from glacier melt than previously assumed. In Peru's Rio Santa, which drains the Cordilleras Blanca mountain range, glacier contribution appears to be between 10 and 20 percent. In the eastern Himalayas, it is less than 5 percent.
"If anything, that's probably fairly large," said Richard Armstrong, a senior research scientist at the Boulder, Colo.-based Cooperative Institute for Research in Environmental Sciences (CIRES), who studies melt impact in the Himalayas.
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| Glacier-fed rivers like the Ganges support more than 1.3 billion people in Asia. But new research questions just how much influence the melting glaciers will have on water availability for people downstream. Photo courtesy of Flickr. |
"Most of the people downstream, they get the water from the monsoon," Armstrong said. "It doesn't take away from the importance [of glacier melt], but we need to get the science right for future planning and water resource assessments."
The Himalayan glaciers feed into Asia's biggest rivers: the Indus, the Ganges and the Brahmaputra in India, Pakistan and Bangladesh, and the Yellow and Yangtze rivers in China. Early studies pegged the amount of meltwater in these river basins as high as 60 or 70 percent. But reliable data on how much water the glaciers release or where that water goes have been difficult to develop. Satellite images can't provide such regular hydrometeorological observations, and expeditions take significant time, money and physical exertion.
New methods, though, are refining the ability to study this and other remote glacial mountain ranges. Increasingly, scientists are finding that the numbers vary depending on the river, and even in different parts of the same river.
"There has been a lot of misinformation and confusion about it," said Peter Gleick, co-director of the California-based Pacific Institute for Studies in Development, Environment and Security. "About 1.3 billion people live in the watersheds that get some glacier runoff, but not all of those people depend only on the water from those watersheds, and not all the water in those watersheds comes from glaciers. Most of it comes from rainwater," he said.
A key step forward came last year when scientists at Utrecht University in the Netherlands, using remote sensing equipment, found that snow and glacier melt is extremely important to the Indus and Brahmaputra basins, but less critical to others. In the Indus, they found, the meltwater contribution is 151 percent compared to the total runoff generated at low elevations. It makes up about 27 percent of the Brahmaputra -- but only between 8 and 10 percent for the Ganges, Yangtze and Yellow rivers. Rainfall makes up the rest.
That in itself is significant, and could reduce food security for 4.5 percent of the population in an already-struggling region. Yet, scientists complain, data are often inaccurately incorporated in dire predictions of Himalayan glacial melt impacts.
"Hyperbole has a way of creeping in here," said Bryan Mark, an assistant professor of geography at Ohio State University and a researcher at the Byrd Polar Research Center.
Mark, who focuses on the Andes region, developed a method of determining how much of a community's water supply is glacier-fed by analyzing the hydrogen and oxygen isotopes in water samples. He recently took that experience to Nepal, where he collected water samples from the Himalayan glacier-fed Kosi River as part of an expedition led by the Mountain Institute.
Based on his experience in the Rio Santa -- where it was once assumed that 80 percent of water in the basin came from glacier melt -- Mark said he expects to find that the impact of monsoon water is greatly underestimated in the Himalayas.
Jeff La Frenierre, a graduate student at Ohio State University, is studying Ecuador's Chimborazo glacier, which forms the headwaters of three different watershed systems, serving as a water source for thousands of people. About 35 percent of the glacier coverage has disappeared since the 1970s.
La Frenierre first came to Ecuador as part of Engineers Without Borders to help build a water system, and soon started to ask what changes in the mountain's glacier coverage would mean for the irrigation and drinking needs of the 200,000 people living downstream. Working with Mark and analyzing water streams, he said, is upending many of his assumptions.
"The easy hypothesis is that it's going to be a disaster here. I don't know if that's the case," La Frenierre said. He agreed that overstatements about the impacts are rampant in the Himalayas as well, saying, "The idea that 1.4 billion people are going to be without water when the glaciers melt is just not the case. It's a local problem; it's a local question. There are places that are going to be more impacted than other places."
Those aren't messages that environmental activists will likely find easy to hear. Armstrong recalled giving a presentation in Kathmandu on his early findings to a less-than-appreciative audience.
"I didn't agree with the doomsday predictions, and I didn't have anything that was anywhere near spectacular," Armstrong said. But, he added, "At the same time, it's just basic Earth science, and we want to do a better job than we have been."
The more modest numbers, they and other scientists stressed, don't mean that glacier melt is unimportant to river basins. Rather, they said, they mean that the understanding of water systems throughout the Himalayan region must improve and water management decisions will need to be made at very local levels.
"We need to know at least where the water comes from," Armstrong said. "How can we project into the future if we don't know where the water comes from now?"
