Peter Matthiessen is indeed headed for a higher kingdom in this work, on both physical and spiritual levels. While the wildlife biologist he is accompanying is on a scientific expedition whose work Matthiessen will share in, he himself is on a very different journey, a quest to regain his footing after the death of his wife and to deepen his Buddhist practice. Such quests have taken place in other places and circumstances, in the absence of mountains and snow; but it is impossible to imagine this one in any other way. The Himalayan glaciers are variously equated with light and purity, grueling hardship and travail; they are both the journey and the inspiration for it. And in the end they are inseparable from his achievement, either literary or spiritual.

The glaciers of the Himalaya contain the largest amount of ice outside of the polar regions. 17% of the mountains' surface is covered by glaciers; the Karakoram range, at the western end, is 37% under ice. Yet the glaciers' increasingly rapid retreat has been documented in recent years by methods ranging from satellite measurements of both horizontal extent and depth to a repeat photography project by filmmaker and mountaineer David Breashears showing the current extent of the ice compared with historical photos taken by earlier climbers such as George Mallory.

Recent summer temperatures in the region have averaged some 3°F higher than normal,1 a greater difference than in most parts of the world. Climate change causes temperatures to rise more rapidly at higher altitudes, just as it does at higher latitudes. The Himalayan glaciers receive much of their annual accumulation from the summer monsoons, and more of that high-altitude precipitation is falling as rain rather than snow. Even in the winter snow is melting, and in warmer air, much of it simply evaporates. Ice cores that have been drilled in some glaciers reveal that the radioactivity that would have appeared in layers deposited since atomic testing began in the 1940s is missing, indicating that there has been no accumulation in all that time.2

A particular problem in these glaciers comes from what has been called "atmospheric brown clouds,"3 concentrations of smog or pollution from the intensive burning of fossil fuels and biomass for industry and home heating and cooking. These clouds deposit black carbon, or soot, on the glaciers, which then absorbs the sun's heat rather than reflecting it, further speeding the warming. Another source of the recent buildup in soot is the increased military activity in the area, which adds the soot from fleets of diesel-powered trucks to the total.

Although local effects vary due to a host of factors such as microclimates and topography, about two-thirds of the Himalayan glaciers are thought to be in retreat. The rate of recession is not only unprecedented, but accelerating, and by mid-century the glaciers are expected to be severely diminished. The greatest of the impacts however will not be on mountaineers, aesthetes, or spiritual seekers, but on the 20% of the world's population who rely on the rivers fed by the glaciers.

All of Asia's major rivers originate in these mountains. While the summer monsoons contribute much of the seasonal flow, the rivers are fed during the rest of the year by melting ice and snow. The greatest decline in flow is expected to affect the Indus and the Brahmaputra, whose upper reaches are more extensive and therefore more dependent on melting ice than on monsoons.4 These two river basins feature exceptionally dense populations – over 20 million people are added per year in India, Pakistan, and Bangladesh5 – and agriculture there depends heavily on irrigation. By mid-century the Indus is expected to support 25 million fewer people than it does now, while the Brahmaputra will support less than half its current population.6 Less fresh water means more contaminated water, which is the major environmental cause of human disease and death, and a major driver of political instability and massive refugee movements, as has been so well illustrated recently in Pakistan.

To address these very serious problems, there must be a vast increase in cooperaton among South Asian nations to manage water usage and develop crops that use less water. Research in the mountains has so far been hampered by security concerns. Whether the shared and urgent need for remedies will overcome deep historic distrust and military solutions remains to be decided.

1 Van Lanen, HAJ & Demuth, S. Regional Hydrology: Bridging the Gap between Research and Practice (IAHS Proceedings and Reports). Wallingford UK: IAHS Press, Mar 2002.

2 Kehrwald, NM; Thompson, LG; et al. "Mass loss on Himalayan glaciers endangers water resources." Geophysical Research Letters, 22 Nov 2008: 35(L22503).

3 Ramanathan, V; Agrawal, M; et al. Atmospheric Brown Clouds: Regional Assessment Report with Focus on Asia. 2008. Nairobi: United Nations Environment Programme.

4 Immerzeel, WW; van Beek, LPH; & Bierkens, MFP. "Climate change will affect the Asian water towers." Science, 11 Jun 2010: 328(5984), pp. 1382-1385.

5 The World Bank. World Development Indicators.

6 Immerzeel et al. Op. cit.