Understanding Desertification: Concept and Definition in Dry Ecosystems

Desertification is one of the most serious environmental threats of our time, yet it remains widely misunderstood. It is not simply the expansion of existing deserts. Instead, it refers to the degradation of land in dry regions – areas where soil loses its productivity, vegetation thins out, and ecosystems decline. This process affects roughly 41% of Earth’s land surface and impacts an estimated two billion people worldwide. Understanding what desertification actually means – how it has been defined, what it looks like on the ground, and who bears the burden – is the first step toward addressing it.

What is desertification? 🔗

At its core, desertification is the process by which productive land in dry environments deteriorates to the point where it can no longer sustain plant life, agriculture, or livelihoods. The most widely accepted definition comes from the United Nations Convention to Combat Desertification (UNCCD), which describes it as land degradation in arid, semi-arid, and dry sub-humid areas resulting from various factors, including climatic variations and human activities. This definition was formally adopted following the 1992 UN Conference on Environment and Development (the Earth Summit in Rio de Janeiro).

A few important aspects of this definition deserve attention. First, it explicitly identifies where desertification occurs – in drylands, not in humid regions. Second, it recognises two categories of causes: natural climate variability (such as prolonged droughts) and human activities (such as overgrazing or deforestation). Third, it focuses on the concept of land degradation rather than simply desert expansion. The UNCCD Convention text further clarifies that combating desertification includes integrated development of land for sustainable outcomes.

How the understanding of desertification evolved over time 🔗

The term “desertification” is relatively modern. French forest engineer André Aubréville is generally credited with coining the term in 1949, using it to describe the conversion of tropical forests in Africa into savannahs and drier ecosystems. As Revista Mètode notes, this early usage focused on a specific type of ecological degradation in tropical Africa – the progressive transformation of forests into increasingly arid landscapes.

The concept gained significant global attention during the devastating Sahel drought of the 1960s and 1970s, which caused severe human suffering and ecological damage across West Africa. In response, the United Nations convened the Conference on Desertification (UNCOD) in Nairobi in 1977. This conference produced one of the first formal definitions: desertification is the decrease or loss of the biological potential of land, which can ultimately lead to desert-like conditions. According to ScienceDirect, this 1977 definition acknowledged that degradation occurs under the combined pressure of adverse climate fluctuations and excessive exploitation of resources.

Verstraete’s perspective on biological potential 🔗

In 1986, Michel Verstraete published an influential review in the journal Climatic Change that examined the evolving definitions of desertification. Verstraete characterised the process as the diminution or destruction of the biological potential of the land – a formulation that emphasises how desertification erodes the capacity of ecosystems to support life. His work highlighted that this degradation stems from the combined pressure of unfavourable climate conditions and excessive human exploitation of land resources.

Verstraete also pointed out that the word “desertification” had acquired many meanings over the decades – some contradictory and most ambiguous. He suggested that researchers should tailor their definitions depending on the specific goals of their work. This acknowledgement of definitional complexity remains relevant today, as scientists and policymakers continue to debate exactly where the boundaries of desertification lie.

The shift from desert expansion to land degradation 🔗

A key evolution in the concept is the shift from viewing desertification as the physical advance of desert borders to understanding it as degradation of land within dryland regions. The IPCC Special Report on Climate Change and Land makes this distinction clear: the difference between desertification and general land degradation is not process-based but geographic. When land degradation occurs in drylands, it qualifies as desertification. This means desertification is not limited to irreversible forms of degradation, nor does it equate to desert expansion. It represents all forms and levels of land degradation occurring in dryland areas.

Physical manifestations of desertification 🔗

What does desertification actually look like on the ground? In 1977, M.Y. Kassas identified several observable physical changes that characterise the process. These indicators remain foundational in desertification science and continue to guide monitoring efforts today.

Loss of vegetation cover 🔗

The most visible sign of desertification is the progressive thinning and disappearance of plant communities. This typically begins with the loss of perennial grasses and deep-rooted shrubs, followed by a shift toward less productive or invasive species. As vegetation disappears, the ecosystem loses its ability to retain soil moisture, cycle nutrients, and support animal life. The Carbon Brief explainer on desertification describes a loss or shift in vegetation type and cover as one of the key processes classified as land degradation.

Soil erosion and loss of organic matter 🔗

Once protective vegetation is gone, the soil becomes exposed to wind and water erosion. EBSCO Research notes that once protective vegetation is lost, wind erosion can strip away even coarse soil materials in just a few years. Much of this eroded material accumulates in moving sand dunes that further threaten any surviving vegetation. Soil organic matter – the nutrient-rich component that makes land fertile – is steadily depleted, reducing the land’s capacity to support crops or natural plant communities.

Sand deposition and dune formation 🔗

In more advanced stages of desertification, sand bodies begin to form and spread across the landscape. Thin layers of sand cover previously productive land, mobile dunes encroach on agricultural fields, and dust storms become more frequent. The UN Office for Disaster Risk Reduction (UNDRR) describes desertification as a degradation process in environments that becomes characterised by blown and undulating sand sheets and mobile dunes, particularly in ecosystems with loose sandy surfaces.

Increased runoff and reduced water retention 🔗

Degraded soils lose their capacity to absorb and retain rainwater. Instead of infiltrating into the ground to replenish aquifers, rainfall runs off quickly across hardened, barren surfaces. This creates a damaging feedback loop: less water availability further stresses the remaining vegetation, which in turn reduces the ecosystem’s ability to capture moisture. Flash flooding alternates with long dry periods, and groundwater tables drop as recharge declines.

Loss of primary productivity 🔗

The cumulative effect of all these physical changes is a marked decline in the land’s biological productivity – its ability to grow plants, sustain animal life, and support human livelihoods. In extreme cases, previously productive grasslands and farmlands transform into barren landscapes that resemble natural deserts but lack the specialised ecosystems that true deserts possess.

Global impact and distribution of desertification 🔗

The effects of desertification are not distributed evenly around the world. While drylands exist on every continent, the burden of desertification falls disproportionately on populations that are already economically and socially vulnerable.

The scale of the problem 🔗

Approximately 41% of Earth’s land surface is classified as drylands. These regions are home to around two billion people who experience relatively low human well-being indicators, such as high infant mortality rates and low per capita income. According to the UN Sustainable Development Knowledge Platform, this population faces consequences that range from food insecurity and poverty to forced migration.

The numbers are striking. Land degradation affects roughly two billion hectares globally, and approximately 12 million hectares of productive land are lost to degradation each year. To put that in perspective, that lost land could produce around 20 million tonnes of grain annually. The UNCCD reports that around 500 million people currently live in areas that have experienced desertification since the 1980s.

Regional variations 🔗

Africa is the most severely affected continent, with approximately two-thirds of its landmass consisting of desert or drylands. Sub-Saharan Africa faces particularly acute challenges, where the majority of rural populations depend directly on the land for their livelihoods. But desertification is by no means limited to Africa. Over 30% of land in the United States is affected. One-fifth of Spain’s land faces desertification risk. In China, decades of sand drift and desert expansion have degraded millions of hectares of cultivated land, rangeland, and forests.

Socioeconomic consequences 🔗

The link between desertification and poverty runs in both directions. Impoverished communities often lack the resources to manage land sustainably, leading to further degradation. At the same time, degraded land deepens poverty by reducing agricultural output and economic opportunities. The Encyclopaedia Britannica notes that the countries along the southern edge of the Sahara are among the poorest in the world and are subject to periodic droughts that devastate their populations.

Desertification also drives migration and conflict. When land can no longer sustain the people who depend on it, communities are forced to move. Rural-to-urban migration intensifies pressure on cities, while cross-border migration creates political tensions. Herder-farmer conflicts in the Sahel region – including in Nigeria, Sudan, and Mali – have been exacerbated by the combination of land degradation, climate change, and population growth.

Why the definition matters 🔗

Getting the definition of desertification right is more than an academic exercise. How we define the problem shapes how we measure it, where we direct resources, and what solutions we pursue. A definition that focuses only on desert expansion might lead to interventions at desert margins, while the broader understanding of land degradation in all drylands opens up a much wider range of policy responses – from sustainable agriculture to land restoration and water management.

The current UNCCD definition – linking desertification to both human activities and climate variability – also carries an important implication: desertification is not inevitable. If human actions contribute to it, then different human actions can slow, halt, or even reverse it. This is the principle behind the concept of Land Degradation Neutrality (LDN), which aims to balance new degradation with restoration and sustainable management practices. The UNCCD’s 2018-2030 Strategic Framework represents the most comprehensive global commitment to achieving this goal.

Understanding desertification – its causes, its physical signs, and its far-reaching human consequences – is essential for anyone concerned with sustainability, food security, or climate adaptation. The stakes are enormous: the health of more than 40% of the planet’s land surface and the livelihoods of billions of people depend on how well we respond.

What do you think? Given that desertification is driven by both natural climate patterns and human activities, where should the primary focus lie – on adapting to climate variability or on changing land-use practices? And how should the responsibility be shared between affected communities and the global community?

References

1. https://sustainabledevelopment.un.org/index.php?page=view&type=30022&nr=556&menu=3170
2. https://www.unccd.int/unccd-faq
3. https://catalogue.unccd.int/936_UNCCD_Convention_ENG.pdf
4. https://metode.org/issues/monographs/science-and-policy-to-combat-desertification.html
5. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/desertification
6. https://link.springer.com/article/10.1007/BF00140520
7. https://www.ipcc.ch/srccl/chapter/chapter-3/
8. https://www.carbonbrief.org/explainer-desertification-and-the-role-of-climate-change/
9. https://www.ebsco.com/research-starters/environmental-sciences/desertification
10. https://www.undrr.org/understanding-disaster-risk/terminology/hips/en0206
11. https://www.unccd.int/land-and-life/desertification/overview
12. https://www.britannica.com/science/desertification