In the Indian Himalayas, you can literally hear the glaciers melting.
The river that rushes through the Lahaul-Spiti Valley is fed almost entirely by melt from the surrounding glaciers. The sound of the river's rapids has never been this loud. The level of the water has never been this high. In other words, the glaciers have never receded this quickly.
"I've never seen such a high water level in this river," says Syed Hasnain, a senior glaciologist at the Energy Resources Institute who has been visiting the Chhota Shigri glacier for 23 years.
"This is 100 percent glacial melt," he adds, standing at the base of the glacier, yelling over the sound of the river. "After 40 years or 50 years, there won't be any flow in this river, and the entire valley will be dried up."
The 15,000 Himalayan glaciers that create the "Water Tower of Asia" -- the largest block of fresh water outside the Polar Ice Caps -- have been melting forever. But they are suddenly melting so fast that they are drying up. It will take decades, but at the rate the earth is warming, they may simply disappear.
"Glaciers in the Himalaya are receding faster than in any other part of the world," the United Nation's Intergovernmental Panel on Climate Change warned last year. "If the present rate continues, the likelihood of them disappearing by the year 2035 and perhaps sooner is very high if the Earth keeps warming at the current rate."
The consequences of that would be enormous. More than a billion people need the rivers supported by the Himalayan glaciers to survive. Across Pakistan, India, Nepal, Bhutan and Bangladesh, rivers that flow from the glaciers give people their water for drinking, irrigation and hydropower.
"We are going to be doomed in the future," Hasnain says. The "entire global community will be affected. It's not only the region will be affected."
And, in India, climate change could imperil the world's oldest religion.
More than 400 million people live off the Ganges River, and the world's billion Hindus consider its water sacred. One drop of Ganges water, they believe, can cure a lifetime of sin.
The glacier that feeds the Ganges, the Gangotri, is melting three times as fast as it was last century.
"Global warming, I think, will finish the globe, will finish Ganga, will finish all of us," says Veer Bhadra Mishra, former chairman of civil engineering at Banaras Hindu University, referring to the Ganges by its commonly used name, Mother Ganga. "We are an endangered species of human beings, and we need your attention, and we need your support, so that our life is saved, and our culture is saved."
Why the Glaciers Are Melting
An hour north of Minali, a town built into the side of the Himalayas (Indians call it a "hill station"), the road turns into a steep hill that leads to the Rohtang Pass. The pass is actually a flat field, surrounded by mountain peaks. It is the largest mountain range on earth.
Mist rolls in and reduces visibility to a few hundred feet. After it leaves, the lines of the mountains are crisp against the blue sky. Even in the summer, their peaks are snowy. The air is thin and cool.
"In India the mountains are always giving you spiritual delight," says P.C.S. Rautela, the former secretary of the Indian Mountaineering Institute.
"You feel," he says, sweeping his hand across the horizon, "that you are amongst gods."