At two miles long and 100 feet deep Tsho Rolpa, Nepal's largest glacial lake, lies menacingly at the head of a quiet valley known as Rolwaling, 40 miles west of Everest. Rolwaling is home to many of the Sherpa youth who work as high-altitude climbing guides. The $60 million Khimti hydropower project, which supplies electricity to Nepal's national grid, is also located nearby. In aerial photographs the lake's narrow, 500-foot-high ice-core dam appears to bulge outward from the water impounded behind it.
At the International Center for Integrated Mountain Development, a research facility on the outskirts of Kathmandu, remote-sensing expert Birendra Bajracharya shows me a computer model of what is likely to happen when Tsho Rolpa bursts. He calmly points to areas where fields and houses would be swept away. I notice a red wash over the village of Beding, just 10 miles below the lake, where the level of the river would climb to more than 50 feet above its present level, flooding the hamlet.
In 1992, after a smaller glacial lake burst nearby, the village's 300 residents petitioned the government to protect them from the swollen Tsho Rolpa, a far more imposing threat. The Nepalese government, with financial aid from the Netherlands, responded by digging a channel in the lake's moraine and constructing a 20-foot-wide flood control gate. Engineers lowered Tsho Rolpa by 10 feet, which has reduced water pressure on the moraine. But lowering the lake has also exposed a larger area of the moraine to the rays of the sun and to ambient air tempera-tures higher than that of the frigid water. This could allow more heat to migrate into the moraine, expediting the melting of its ice-and-rubble core.
John Reynolds, managing director of Reynolds Geo-Sciences, an environmental engineering firm based in Wales that specializes in glacial haz-ard assessment and remediation projects, remains concerned. "Tsho Rolpa is still at risk," he says. "To make it truly safe, the level should be drawn down at least another 37 feet" -- at a cost of about $12 million. By contrast, if the lake bursts, the cost in repairs and lost revenue for the Khimti hydropower plant could reach $22 million, not to mention the loss of property and livestock belonging to the subsis-tence villagers who live below the lake.
And yet governments and aid agencies are reluctant to finance glacial lake studies or remediation work. It's a political fact of life: Funds for emergency disaster relief are easier to come by than support for preventive measures. Which means the mountain villagers least responsible for global warming, and least able to affect its outcome, will pay the consequences.
