Lester R. Brown
Chapter 3. Climate Change and the Energy Transition: Melting Glaciers, Shrinking Harvests
If all the earth’s mountain glaciers melted, they would raise sea level only a matter of inches. But it is the summer ice melt from these glaciers that sustains so many of the world’s rivers during the dry season. Thus, as temperature rises there will be a shrinkage of river-based irrigation water supplies. In early 2009 the University of Zurich’s World Glacier Monitoring Service reported that 2007 marked the eighteenth consecutive year of glacier retreat. And glaciers are melting at double the rate of a decade ago. 49
Mountain glaciers are melting in the Andes, the Rocky Mountains, the Alps, and elsewhere, but nowhere does this melting threaten world food security more than in the Himalayas and on the Tibet-Qinghai Plateau, where the melting of glaciers could soon deprive the major rivers of India and China of the ice melt needed to sustain them during the dry season. In the Indus, Ganges, Yellow, and Yangtze River basins, where irrigated agriculture depends heavily on rivers, this loss of dry-season flow will shrink harvests and could create unmanageable food shortages. 50
The world has never faced such a predictably massive threat to food production as that posed by the melting mountain glaciers of Asia. As noted in Chapter 1, China and India are the world’s leading wheat producers, and they totally dominate the rice harvest. 51
The IPCC reports that Himalayan glaciers are receding rapidly and that many could melt entirely by 2035. If the giant Gangotri Glacier—whose ice melt supplies 70 percent of the Ganges flow during the dry season—disappears, the Ganges could become a seasonal river, flowing during the rainy season but not during the dry season when irrigation needs are greatest. 52
In China, which is even more dependent than India on river water for irrigation, the situation is particularly challenging. Chinese government data show that the glaciers on the Tibet-Qinghai Plateau that feed the Yellow and Yangtze Rivers are melting at a torrid pace. The Yellow River, whose basin is home to 147 million people, could experience a large dry-season flow reduction. The Yangtze River, by far the larger of the two, is threatened by the disappearance of glaciers as well. The basin’s 369 million people rely heavily on rice from fields irrigated with its water. 53
Yao Tandong, one of China’s leading glaciologists, predicts that two thirds of China’s glaciers could be gone by 2050. “The full-scale glacier shrinkage in the plateau region,” Yao says, “will eventually lead to an ecological catastrophe.” 54
Agriculture in the Central Asian countries of Afghanistan, Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan depends heavily on snowmelt from the Hindu Kush, Pamir, and Tien Shan mountain ranges for irrigation water. Nearby Iran gets much of its water from the snowmelt in the 5,700-meter-high Alborz Mountains between Tehran and the Caspian Sea. 55
In Africa, Tanzania’s snow-capped Kilimanjaro may soon be snow- and ice-free. Ohio State University glaciologist Lonnie Thompson’s studies of Kilimanjaro show that Africa’s tallest mountain lost 84 percent of its ice field between 1912 and 2007. He projects that its snowcap could disappear entirely by 2015. Nearby Mount Kenya has lost 7 of its 18 glaciers. Local rivers fed by these glaciers are becoming seasonal rivers, generating conflict among the 2 million people who depend on them for water supplies during the dry season. 56
Bernard Francou, research director for the French government’s Institute of Research and Development, believes that 80 percent of South American glaciers could disappear within the next decade. For countries like Bolivia, Ecuador, and Peru, which rely on glacial melt for household and irrigation use, this is not good news. 57
Peru, which stretches some 1,600 kilometers along the vast Andean mountain range and is the site of 70 percent of the earth’s tropical glaciers, is in trouble. Some 22 percent of its glacial endowment, which feeds the many Peruvian rivers that supply water to the cities in the semi-arid coastal regions, has disappeared. Lonnie Thompson reported in 2007 that the Quelccaya Glacier in southern Peru, which was retreating by 6 meters per year in the 1960s, was then retreating by 60 meters annually. In an interview with Science News in early 2009, he said, “It’s now retreating up the mountainside by about 18 inches a day, which means you can almost sit there and watch it lose ground.” 58
Many of Peru’s farmers irrigate their wheat and potatoes with the river water from these disappearing glaciers. During the dry season, farmers are totally dependent on irrigation water. For Peru’s 29 million people, shrinking glaciers will eventually mean a shrinking food supply. 59
Lima’s 8 million residents get most of their water from three rivers high in the Andes, rivers that are fed partly by glacial melt. While the glaciers are melting, the rivers swell, but once they are gone, the river flows will drop sharply, leaving Lima with a swelling population and a shrinking water supply. 60
In early 2009 Wilfried Haeberli, head of the World Glacier Monitoring Service, reported that some 90 percent of the glacial ice in Spain’s Pyrenees Mountains has disappeared over the last century. These glaciers feed the Gállego, Cinca, and Garona Rivers that flow southward, supplying summertime water in the region’s foothills and plains. 61
The story is the same everywhere. Daniel Fagre, U.S Geological Survey ecologist at Glacier National Park, reported in 2009 that the park’s glaciers, which had been projected to disappear by 2030, may in fact be gone by 2020. 62
In the southwestern United States, the Colorado River—the region’s primary source of irrigation water—depends on snowfields in the Rockies for much of its flow. California, in addition to depending heavily on the Colorado, also relies on snowmelt from the Sierra Nevada range in the eastern part of the state. Both the Sierra Nevada and the coastal range supply irrigation water to California’s Central Valley, the country’s fruit and vegetable basket. 63
With a business-as-usual energy policy, global climate models project a 70-percent reduction in the amount of snow pack for the western United States by mid-century. A detailed study of the Yakima River Valley, a vast fruit-growing region in Washington State, conducted by the Pacific Northwest National Laboratory of the U.S. Department of Energy shows progressively heavier harvest losses as the snow pack shrinks, reducing irrigation water flows. 64
The snow and ice masses in the world’s leading mountain ranges and the water they store are taken for granted simply because they have been there since agriculture began. As the earth gets hotter, we risk losing these “reservoirs in the sky” on which both farmers and cities depend.
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