Concepts
Desertification
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The gradual degradation of fertile land into arid desert through some combination of natural climate variability and human land use such as overgrazing, deforestation and continuous unrotated tillage, with drylands covering some 40 percent of the world's land and home to more than two billion people. How much of any one region's desertification, the Sahel above all, is natural climate cycle versus human pressure is genuinely disputed rather than settled: since 1900 the Sahara has pushed roughly 250 kilometers further south across a 6,000-kilometer front, and the Sahel has lost around 650,000 square kilometers of productive land over the last fifty years, but satellite vegetation records since the 1980s also show partial regreening in wetter years, which does not sit easily beside a simple story of one-way human-driven collapse.
Climate-cycle and human-land-use explanations of Sahel desertification are both supported by parts of the record, and the relative weight of the two is not settled; see the paired open question on this entity for what would resolve it.
Facts
Cross-Tradition Connections
Associated With
Dust Bowl, Milestones The Dust Bowl is cited as the American precedent for large-scale land-degradation response, including as a parallel for China's modern reforestation efforts
Monoculture, Concepts Intensive farming and monoculture are named among the article's own agricultural drivers of soil nutrient depletion
Soil Erosion, Concepts Vegetation loss and topsoil loss compound each other in a degrading dryland
Sources
1. Andre Aubreville (Wikipedia)
Wikimedia FoundationIntroductionQuote, Introduction
He was the first scientist to introduce the term desertification, in his 1949 book
Desertification (Wikipedia)
Wikimedia FoundationLead section; Causes and Sahel sectionsQuote, Lead section; Causes and Sahel sections
Desertification is a type of gradual land degradation of fertile land into arid desert due to a combination of natural processes and human activities.
Open Questions (1 open question)
Is the Sahel's desertification driven mainly by long-term climate variability or by human land use?
Satellite vegetation studies since the 1980s show the Sahel partly regreening in wetter years, complicating a simple story of runaway human-caused desert advance, while heavily grazed and continuously tilled zones keep degrading even in wet years, so researchers read the same record differently depending on which zones and years they weight.
What would resolve this Long-run, zone-by-zone studies separating rainfall-driven vegetation change from land-management effects, ideally paired with soil-condition data rather than vegetation greenness alone, would let the two drivers be weighed apart rather than argued as a single trend.
Climatology and agroecologyDesertification (Wikipedia)
Dissenting Readings (1 dissenting reading)
Description
Vegetation-index studies using satellite data found the Sahara's southern edge greening rather than steadily advancing through much of the 1980s and 1990s rainy years, arguing that rainfall variability, not runaway human overuse, is the dominant driver of most of the region's vegetation swings, and that the standard desertification narrative overstates humanity's share relative to climate.
A dissenting reading, from Satellite remote-sensing researchers tracking Sahel vegetation trendsDesertification (Wikipedia), Wikimedia Foundation
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