Above a small village on the steep slopes of the Andes, a Quechua farmer holds a half dozen potatoes cupped in his hands. The seed potatoes are red, blue, and brown. The translucent sprouts that have started to emerge in preparation for planting are tinged with purple and gold.

Four factors-geography, sunlight, temperature, and rainfall-and their interplay are critical to farming. Global warming or any other form of dramatic climate change will have a profound impact on this equation.

The air is often crisp and cool when the Quechua farmer plants his seed potatoes. But what would happen if the weather at planting time was hot and humid or if heavy rainfalls were to wash away the thin soil of his field? In fact, climate change is potentially catastrophic for the farming traditions that are central to many Native cultures, and critical to the livelihoods of the majority of Native peoples in Latin America.

Public debate around global warming tends to focus on the large-scale industrial farms of the North. The Quechua farmer and others who work on a small scale and use traditional methods have been largely ignored. However, as the world slowly comes to terms with the threat of climate change, Native farming traditions will warrant greater attention. This is owing to the fifth factor critical to farming: the seed itself.

The Andean potato is one of the world's most important food crops. Each year in Africa, Asia, Europe, and the Americas, roughly 50 billion acres are planted with potatoes descended from plants first domesticated in South America 7,000 years ago. Along with other crops first domesticated by indigenous peoples-such as corn from Central America, squash, beans and tomatoes from the Andes, and rice from South Asia-potatoes literally feed the world. And when these global crops are no longer suited to the environment in which they are grown, when their resistance to disease and pests begins to fail or the climate itself changes, the best way to rejuvenate the breeding stock will be to introduce new genetic material from the vast diversity of crop varieties still maintained by indigenous peoples.

The spectrum of colors displayed in the Quechua farmer's potatoes reflects the fact that each is genetically distinct. The genetic diversity of the half-dozen potatoes he holds in his hands is roughly comparable to the diversity you might find in a North American supermarket. However, it is only a small sample of the 100 to 200 potato varieties planted each year on the Andean slopes. And even this represents only a fraction of the total diversity found throughout the region. From Colombia to Chile, it is estimated that indigenous peoples cultivate at least eight potato species and more than 3,000 varieties. The Andes also sustain at least 100 more wild potato species.

The extraordinary genetic diversity of Andean potatoes and of other Andean crops such as squash and beans is the product of millennia of plant breeding. And much of this plant breeding has been driven by the need to adapt crops to the extraordinary climatic diversity of the region.

The Andes is one of the world's most complex and varied regions in terms of geography and climate. Along the two axes of latitude and altitude, the Andes encompasses fully two-thirds of all possible combinations of climate and geography found on Earth, including cloud forests, deserts, rolling grasslands, lakes, marshes, glacial plains and the headwaters of the Amazon.

Add extreme weather occurrences to the wide-ranging geographical variations and agricultural challenges become magnified. There are many ways farmers can respond to unfavorable conditions and climate changes. If rainfall is insufficient, they can use artificial irrigation. If summers are too long and too hot, they can apply more fertilizers to bring on early maturation. Or they can do as Andean farmers have done over the millennia and adapt the crops to suit the climate and conditions. Over thousands of years, Native peoples introduced agriculture into virtually every ecosystem in the Andes and adapted an incredible diversity both of crops and crop varieties to these conditions. The most important of these crops, the potato, has been adapted to every environment except the depth of the rainforest or the frozen peaks of the mountains.

Today, facing the likelihood of dramatic disruptions to the climatic conditions for agriculture worldwide, indigenous farmers provide a dramatic example of crop adaptation in an increasingly extreme environment. More importantly, Native farmers also safeguard the crop diversity essential for future adaptations.

Downslope is the best known historical site of Andean culture, Machu Picchu. Here the mountainside has been carved in all directions with hundreds of terraces, some as narrow as a few feet in width. Anthropologist Jack Weatherford, in his book Indian Givers: How the Indians of the Americas Transformed the World, suggests that Machu Picchu was not primarily a ceremonial site, as is sometimes assumed, but the center of Incan agricultural research. He speculates that the terraces were created as test plots mirroring the various climate and soil conditions of key regions of an empire that spanned much of the Andes. On these terraces, new varieties of food and textile crops would have been bred and tested before being distributed to local farmers for further adaptation.

To get a rough idea of the likely effects of climate change on agriculture, imagine the terraces of Machu Picchu repopulated as a kind of microcosm of contemporary farming in the Americas. In this microcosm, indigenous farmers have access to only a few narrow terraces representing the most difficult growing conditions. The indigenous people continue to work the land, sustaining themselves through their knowledge of the terraces and through the preservation and continued improvements of crops adapted to these conditions.

Now imagine that a natural process such as erosion, which would normally take place imperceptibly over thousands of years, is suddenly accelerated so the impact is felt in a single generation. Imagine that over a period of 20 years, the terraces of Machu Picchu drop 500 feet or more closer to sea level. As altitude decreases, temperature increases. But on individual terraces, the results are more complex and variable. Precipitation levels, for example, are also affected. The higher temperatures lead to increased water evaporation. Rain strikes some slopes, and the water available to some crops increases. Other slopes, however, are passed by. Some experience increased cloudiness, while rainfall diminishes and streams dry up. The world of insects and microorganisms is radically altered.

One can imagine that the indigenous farmers initially would be able to survive such changes. Natural weather cycles such as El Niño already vary farming conditions enormously with droughts and floods. Many indigenous farmers cope with these naturally occurring fluctuations by conserving seed stock suited to a wide range of growing conditions, by storing food in forms such as dried potatoes, and by maintaining hardy wild foods that can be drawn on in times of extreme weather conditions.

Eventually, on many terraces, conditions will emerge unlike any ever faced by the indigenous farmers. Even if it were theoretically possible to farm under these conditions, the pace of traditional plant breeding would be too slow for the rate and extent of change now facing the indigenous farmers. Adapting crops and knowledge that had been so precisely suited to entirely different conditions would require greater resources than those available to the indigenous farmers. At this point, traditions of indigenous agriculture handed down through the ages could well collapse.

Before this point is reached, however, non-indigenous farmers on the richer neighboring terraces must confront a crisis of their own. Pests and diseases that failed to gain a foothold among the diverse crops of the indigenous farms spread rapidly through the monocultures of the white and mestizo farmers with devastating results. Even for those farmers who can afford them, increased pesticides will not solve the problem. The crops themselves must be radically and quickly altered. The wealthiest of these farmers have the technological resources for plant breeding. What they lack are the "raw materials," the genetic characteristics for resistance. At this point, conceivably, a new relationship between indigenous and non-indigenous farmers might be negotiated to prevent the collapse of farming.

How realistic is this scenario? The fact is that traditional systems of indigenous agriculture stand in sharp contrast to the system of food growing that now predominates in the United States and Canada, but the two systems are intricately linked. And this link may be the key to how climate change impacts global agriculture.

In this industrial model of agriculture, one or two crop varieties are grown over vast areas. Instead of trying to use local resources of soil and water optimally and sustainably, the natural environment is all but ignored and uniform growing conditions are fabricated through large-scale irrigation and the intensive use of artificial fertilizers and pesticides.

In the industrial agricultural system, a handful of basically similar potato varieties, all of which require nearly identical soil conditions, temperature, rainfall and growing seasons, account for almost all global production. In fact, in the United States, the Russet Burbank (the variety preferred by fast food restaurants and manufacturers of potato chips and frozen french fries) accounts for 60 percent of commercial production. More money is spent radically modifying potato-growing conditions with artificial pesticides and fertilizers than is spent on any other crop.

As this industrial agricultural model expands throughout the world, it is more and more often in conflict with the survival of the indigenous peoples whose lands are being appropriated for plantations and whose ecosystems are being destroyed by river diversions and pesticide run-offs. Ironically, as the industrial model of agriculture expands, it is also becoming ever more dependent on indigenous peoples.

Monocultures-large, uninterrupted fields of uniform crops-create ideal conditions for disease and pests to evolve and spread. Growing these crops around the world in conditions that have been made uniform by large-scale irrigation and use of artificial pesticides and fertilizers further worsens the situation. When crops fail, agribusiness responds by discarding the old varieties for new ones bred for greater resistance either to the latest pests and diseases or to the chemicals used to fight these pests. But because these so-called improved varieties are again grown in global monocultures, ideal conditions are once again created for new pests and diseases to emerge or for the old pests and disease to evolve and overcome the new defenses. It is a vicious cycle often compared to running on a treadmill.

The inherent dangers of this approach to farming have long been clear. In the autumn of 1846, nearly 90 percent of the Irish potato crop rotted in the fields. Potatoes, introduced from the Americas decades before, had become the staple diet of Irish farm laborers. When the potatoes rotted, the laborers starved. By the end of the next autumn and the second crop failure, more than 1 million people had died in the "Irish potato famine."

The destruction of the Irish potato crop was caused by a fungal disease known as "late blight," but it is linked to climate and farming practices. The disease likely originated in Central America near the present-day border of Mexico and Guatemala. Significantly, although indigenous farmers in the region had apparently lived with the blight for generations, there is no indication that the blight had ever caused starvation before it was introduced to Ireland. The indigenous farmers were likely protected against the blight by the great genetic diversity among the potatoes that they grew and by the overall diversity of their diet. In contrast, the Irish laborers were almost wholly dependent on potatoes descended from two closely related varieties. When damp weather in late summer gave the blight its first foothold in Ireland, it spread quickly through these fields of largely uniform crops with devastating results.

Potato farmers eventually recovered from the blight by breeding new potato varieties with a more varied genetic heritage. Plant hunters were also able to locate blight resistant varieties among indigenous farm communities in Central and South America and recent breeding programs have attempted to incorporate these traits.

Despite such lessons from history, the overall trend of industrial agriculture over the last 100 years has been toward less, rather than more, diversity. In North America alone, an estimated 97 percent of commercial crop varieties have become extinct in this century, either because seed companies have streamlined their inventories or because the most important buyers-the food processors, restaurants, and supermarkets-have no need for such diversity.

Seed banks may help stem this rate of extinction but they are by no means a solution. No seed bank or network of seed banks could ever represent the infinite variation in climate adaptation even within plant varieties that occurs at the level of each community or farmer's fields. Furthermore, plant varieties conserved only in seed banks have had their evolution halted so that they no longer interact and adapt to the constantly changing growing conditions found in farmers' fields.

As a growing number of conservation organizations, government programs and international agencies have come to recognize, true conservation of genetic diversity can only take place in farmers' fields. Unfortunately, the ultimate consequence of the industrial model of agriculture is farm fields that in the words of the U.S. National Academy of Sciences are "impressively uniform . . . and impressively vulnerable."

This impressive vulnerability of industrial agriculture is key to understanding how climate change will likely have an impact on global agriculture and on the relationship between industrial agriculture and indigenous farming communities. Faced with rapid and dramatic climate change, the impressively vulnerable industrial farm can conceivably continue to use large-scale irrigation and artificial fertilizers to counter the effects of changing temperature and precipitation. The cost would be high, no doubt much higher than many farmers in the southern hemisphere or Third World could bear, and probably higher than could be absorbed by most marginal to medium-scale farmers in North America or Europe. At the same time, these changes might be welcomed by the largest agribusiness enterprises, which could afford the higher levels of industrial inputs and could profit from this new advantage.

Ultimately, however, changes in temperature are not the only serious challenge faced by the industrial farmer. Crop losses to insect pests have steadily increased throughout this century despite-or perhaps because of-ever-greater use of pesticides. Outbreaks of famine-threatening diseases such as late blight are becoming more and more frequent. Not only has industrial agriculture failed to eradicate the blight, the blight has evolved into new and more virulent forms. Insects and disease are able to spread amidst modern plant breeding and industrial controls because of their vast numbers and rapid rate of reproduction. Together these factors allow disease and insects to quickly adapt and thrive in the face of agribusiness controls or climate changes. Sudden, dramatic climate change will inevitably catalyze new evolutionary pathways to which industrial agriculture cannot possibly respond without drawing on the genetic diversity preserved by indigenous peoples.

At the same time, the survival of Native farmers ultimately depends on the concentrated research capacity of the industrial farm system. Native farmers, who have successfully domesticated and adapted countless plant varieties over the millennia, soon will be up against the challenge of accelerating the pace of adaptation to bring about substantial new adaptations within a generation. The fact is that the scale of industrial agriculture, the wealth that it has generated, and the ample support of publicly funded research have led to a number of significant breakthroughs in just this kind of plant breeding.

Take again the example of the potato. Most potatoes are grown from sprouted potato eyes rather than from seed. As a result, the genetic makeup of the resulting plant is identical to this single parent. Furthermore, since the potatoes that produce these sprouts grow side by side with their parents in the soil, disease is passed on from one generation to the next and tends to build up over time.

Indigenous farmers in the Andes typically grow most potatoes from sprouted potatoes. Andean farmers usually also grow some potatoes from the "true seeds" that are sometimes produced above ground on the potato stalk once its flowers have been pollinated. Potatoes grown from true seed are highly random, almost unpredictable combinations of the genes from the two parents. Producing a useful new variety in this way requires both a keen knowledge of the plant and the patience of a lifetime.

Scientists working for Northern institutions, transnational corporations and the International Potato Center in Peru have made a number of recent advances based on these traditional techniques. One is the use of tissue cultures grown under sterile laboratory conditions to produce sprouting potatoes from which most or all soil-borne diseases have been eliminated. Another is a technique for creating true potato seeds that, like the seeds of hybrid corn or beans, produce consistent, uniform offspring. Finally, genetic engineering has permitted the rapid identification and insertion of specific genetic characteristics into potato breeding stock.

Current technologies, however, have not addressed the needs or concerns of indigenous peoples. In the best case, tissue culture technology is being used to maintain viability of potato varieties that might otherwise be discarded. However, contrary to developments with "true potato seed," this technology has been applied exclusively to preservation and breeding of potato varieties for large-scale, commercial monocultures. In the worst case, biotechnology is being used, not to accelerate the results that could be obtained through traditional breeding, but to create new and potentially hazardous cross-species fusions that could never occur in nature. One such example is the hybrid of potato and toxic bacteria created by Monsanto that defends itself against pests by poisoning them. In addition, with these new advances, the scientists are using the Western intellectual property system to claim patent and patent-like rights over the technology and its products, which allows them to monopolize the profits and exert monopoly control over how the technology is applied.

What is needed is a way to apply these technologies in a dramatically different way. Scientists with the resources to accelerate plant breeding must work in partnership with the communities and peoples who maintain contemporary crop diversity. Local farmers must not be prohibited from adapting the products of new plant breeding to their own needs, but enabled to do so. Call it the Machu Picchu model.

Recent trends in international law would support this kind of paradigm shift in agricultural research as a right of indigenous peoples. The legally binding Convention on Biological Diversity and ILO Convention 169, the moral principles of the Draft Declaration on the Rights of Indigenous Peoples and the UNESCO Model Provisions for the Protection of Folklore-as well as the broader concept of Farmers' Rights being developed within the UN Food and Agriculture Organization, which would apply to any traditional farmer-all point toward a new regime of collective rights over knowledge and resources for the traditional innovators and knowledge keepers. The elements of such a rights regime as it is emerging in the UN system would include the right to prior informed consent of any use or elaboration of indigenous knowledge or genetic resources, the right to a fair share in the benefits derived from the exploitation of indigenous knowledge and resources, and the right to participate as full partners in this development.

Perhaps most significantly, the Biodiversity Convention recognizes that information exchange and technology transfer should be two-way exchanges. Although arguably intended to promote corporations' access to genetic resources in the southern hemisphere, the Convention makes explicit-and legally binding-the right of indigenous peoples to have access to and share in the benefits of the scientific resources of the North. The wording of the Convention suggests that these rights are held not just at the international or national level, but by each village or community.

As yet, there is no enforcement mechanism to back up this emerging body of indigenous rights. In general, enforcement has lagged far beyond the recognition of rights in international law. Five decades after the recognition of the crime of genocide, the UN system is only just now setting up criminal courts to try those accused of such crimes. The enforcement of rights pertaining to indigenous knowledgend biolocal resources is currently evolving at the intergenerational pace of traditional plant breeding. But if the effects of climate change are already upon us, the evolution of such enforcement mechanismmust be dramatically and immediately accelerated. The ability of future generations to feed themselves depends on it.