Alon Tal*

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingChapterpeer-review

6 Scopus citations


Desertification is among the most misunderstood- And the most neglected-of the world's global environmental challenges. Images of irrepressible waves of sands overwhelming civilization are not entirely fictitious. Indeed, the spectacle can be witnessed every day from the Sahara to China; frequently, natural phenomena can lead to desertification.1 For the most part, however, desertification refers to the much less dramatic but far more pernicious steady decrease in land productivity that takes place in drylands. It is important to emphasize another misconception. Although they may contain productive oases or river valleys, true deserts (arid and hyperarid lands) are typically not the areas in which desertification on a large scale takes place. Rather, it is in the semiarid and subhumid drylands that receive low, often seasonable rainfall and support soils with modest organic content, where the relatively low-land productivity may decline even further. When the nations of the world finally negotiated a treaty to "combat" desertification in 1994, they defined the phenomenon as "land degradation in arid, semiarid and dry sub-humid areas resulting from various factors, including climatic variations and human activities."2 A higher resolution definition put forward by the United Nations Environmental Program (UNEP) characterizes desertification by five processes that damage land productivity: (1) vegetation degradation, (2) water erosion of soils, (3) wind erosion of soils, (4) soil salinization, and (5) soil compaction-in the drylands. Natural shifts in climate or meteorological processes can surely contribute to these processes. For example, geologists believe that the change in wind directions after the Holocene period replaced the plentiful deposition of Sahara loess in Israel's Negev Desert, with smaller quantities that arrived from Saudi Arabia. With replenishment diminished, loss of soil due to natural erosive processes was inevitable.3 But generally desertification refers to the loss of soil productivity that is driven by such anthropogenic activities as deforestation, overgrazing, or poorly considered water management. There is nothing new about these activities. Farmers have been aware of the vulnerability of their lands to human abuse and of phenomena like irrigation, waterlogging, soil salinization, or riff and gully erosion from time immemorial. And the ancients were not without effective responses. The Old Testament is full of stories that refer to the importance of imposing stock limits in rangelands (as in the pasture distribution between Abraham and Lot) or normative prescriptions, such as the requirement of crop rotation and sabbatical years for soil rejuvenation. 4 Their terraces still define the gnarled landscape of Israel. Although it is not clear that the farmers of old were fully cognizant of desertification processes when adopting such practices, and their implementation alone cannot guarantee the prevention of desertification, they can meaningfully contribute to sustainable land management. Jared Diamond, a Pulitzer Prize-winning ecologist, described the process that undermined many a civilization in the ancient Near East: "Because of low rainfall and hence low primary productivity, (proportional to rainfall), regrowth of vegetation could not keep pace with its destruction, especially in the presence of overgrazing by abundant goats. With the tree and grass cover removed, erosion proceeded and valleys silted up, while irrigation agriculture in the low-rainfall environment led to salt accumulation. . . . Thus, Fertile Crescent and eastern Mediterranean societies had the misfortune to arise in an ecologically fragile environment. They committed ecological suicide by destroying their own resource base."5 But "desertification" only emerged as a salient term of reference and a modern international problem during the second half of the twentieth century. As early as 1927, a French biologist working in Tunisia documented the low productivity of rangelands there.6 Twenty-two years later, the French colonial forester A. Aubreville coined the term "desertification" itself (in French) when he described the grim situation in West Africa: "The closed forests are shrinking and disappearing, like evaporating spots. The trees of the open forests and savannas become more and more spaced out. On all sides, the bare skin of Africa appears as its thin green veil of savanna burns releasing a grey fog of dust into the atmos- phere. Arable land is carried away by the yellow waters of flood. Slabs of sterile truncated soil, bearing tufts of grass around uprooted bushes, recall a kind of leprosy that is spreading over the face of Africa."7 It would take another twenty years, and considerable human misery, before the world woke up to the extent of the challenge, and it was enormous. The 2005 Millennium Ecosystem Assessment reported that the "number of people affected by desertification is likely larger than any other contemporary environmental problem."8 Desertification is therefore a relatively modern environmental phenomenon even though its symptoms have been well documented in the past- from ancient Greece to Ottoman Palestine. Part of the reason for the present acceleration of desertification processes is the link between environmental damage and the exceedance of human carrying capacity on the relatively fragile drylands. Only recently have the sheer numbers of human beings on the planet created extreme population pressures on a global scale. Several salient events and activities over the past century have addressed this global challenge. These can be divided into two categories: (1) natural disasters that have raised public awareness about the severity of the problem; and (2) more recently, international or local efforts that have demonstrated that this trend need not be destiny; just as humans have created the desertification crisis, humans can solve it. Unfortunately, there are far more examples from the natural disaster category than the latter. The international community that has mobilized to address several insidious and vexing global environmental problems (such as the depletion of the ozone layer, whale extinctions, or trade in endangered species) has found neither the resources nor the political will to make a serious commitment to changing the planet's desertification profile. Unlike most environmental challenges that require proscriptions on development and cooperative restraint in human interaction with the global commons, the remedies required to stop and reverse desertification are quite the opposite in nature. They require thoughtful investment in sustainable development in the drylands of developing nations. This by its very nature is a gradual process, not given to dramatic turns. At the same time, unless the resources and stamina for such a sustained process are garnered, desertification will continue to be an environmental orphan that spirals out of control, leaving agricultural failure, famine, and refugees in its wake.

Original languageEnglish
Title of host publicationThe Turning Points of Environmental History
PublisherUniversity of Pittsburgh Press
Number of pages16
ISBN (Print)0822961180, 9780822961185
StatePublished - 2010
Externally publishedYes


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