Desertification is land degradation in dry regions caused by a combination of climate shifts and human activity. It doesn’t mean a desert is literally expanding outward like a growing stain on a map. Instead, it describes the process by which previously productive land loses its soil quality, vegetation, and ability to support life. The distinction matters: desertification can happen in patches far from any existing desert, wherever dryland soils are pushed past their limits.
The problem is enormous in scale. An estimated 580 million people live in areas at high risk, mostly in low-income countries. Desertification, land degradation, and drought collectively cost the global economy roughly $878 billion every year.
What Desertification Actually Looks Like
A common misconception is that desertification means sand dunes swallowing villages. The reality is usually less dramatic but more insidious. The Intergovernmental Panel on Climate Change defines desertification as all forms and levels of land degradation occurring in drylands, not just irreversible damage or the advance of desert edges. It can look like cracked, compacted soil that no longer absorbs rain. It can look like a field that produces half the crop it did a decade ago, or a pasture where only the hardiest weeds survive.
The degradation happens through three overlapping channels: physical, chemical, and biological. Physical degradation includes wind and water erosion stripping away topsoil and breaking down soil structure. Chemical degradation involves salt buildup in irrigated fields, pollution from fertilizers, and contamination by trace elements or microplastics. Biological degradation is the loss of organic matter and the micro- and macroorganisms that cycle nutrients through the soil. When those organisms disappear, the soil loses its ability to feed plants even if it still looks like dirt.
At current rates of topsoil loss worldwide, some researchers have warned that all of the world’s topsoil could become unproductive within 60 years.
Human Activities That Drive It
Climate variability plays a role, but human activity is the accelerant. Three practices do the most damage.
Overgrazing is one of the leading causes. When too many livestock feed on the same land for too long, they strip vegetation down to bare soil. Without plant roots holding the ground together, wind and rain carry the topsoil away. In semi-arid regions where rainfall is already scarce, that soil may never recover on a human timescale.
Unsustainable farming degrades land through repeated tillage that breaks down soil structure, monoculture planting that depletes specific nutrients, and irrigation practices that cause salt to accumulate near the surface. As water evaporates from irrigated fields in hot climates, dissolved salts concentrate in the upper layers of soil, eventually reaching levels that kill most crops. This salinization is one of the most difficult forms of degradation to reverse.
Deforestation and fire thin out vegetation cover, exposing bare soil to erosion. Trees and shrubs act as windbreaks and their root systems anchor the ground. Remove them, and you get a surface that dries faster, erodes faster, and reflects more heat back into the atmosphere.
The Feedback Loop That Makes It Worse
Desertification doesn’t just respond to climate change. It feeds it. Research published in the Proceedings of the National Academy of Sciences describes a feedback loop involving dust: when human activities like grazing and cultivation expose and disrupt topsoil, dust emissions increase. That airborne dust drifts into cloud-forming zones and suppresses rainfall in two ways. First, dust particles interfere with how water droplets form inside clouds, reducing the amount of rain that falls. Second, dust absorbs solar radiation and warms the surrounding air, which stabilizes the atmosphere and prevents the rising air currents that create rain clouds in the first place.
Less rain means drier soil. Drier soil means more dust. More dust means even less rain. This cycle can be self-sustaining once it starts, meaning a region doesn’t need continued human pressure to keep degrading. The initial disruption of the topsoil can set the process in motion, and atmospheric physics takes it from there.
On the ground, this feedback compounds the effects of rising global temperatures. Warmer air pulls moisture out of soil faster, shortening the window plants have to grow between rains. Droughts become longer and more frequent, and each one leaves the land slightly less capable of recovering before the next one hits.
Who It Affects Most
Climate-driven expansion of drylands has pushed over 5 million square kilometers of land toward desertification conditions, affecting an estimated 580 million people. The burden falls disproportionately on countries with the fewest resources to respond. In sub-Saharan Africa, South Asia, and parts of Central Asia, rural communities depend directly on the land for food, fuel, and income. When that land degrades, the consequences cascade: crop failures lead to food insecurity, food insecurity drives migration, and migration strains already crowded urban areas.
The economic toll extends beyond farming. Degraded land reduces the availability of clean water, limits grazing for livestock, and shrinks the natural resource base that supports local economies. The $878 billion annual global cost estimated by the United Nations Convention to Combat Desertification captures only the measurable economic losses, not the health impacts, displacement, or conflict that follow.
How Degraded Land Can Be Restored
Desertification is not always permanent. Several proven techniques can slow or reverse it, especially when applied before the soil is completely depleted.
- Contour farming: Planting crops in rows that follow the natural contours of the land, rather than in straight lines, dramatically reduces erosion from rainfall. Water flows along the rows instead of rushing downhill, giving it time to soak into the soil. Farmers who have adopted this method report significant reductions in washing and erosion even during heavy rains.
- Conservation tillage: Reducing how often and how deeply soil is plowed preserves its structure and the organisms living in it. Combined with crop rotation, this approach rebuilds organic matter and breaks pest cycles without exposing bare ground.
- Farmer-managed natural regeneration: Rather than planting new trees, this technique involves protecting and nurturing the stumps and root systems of trees that have been cut down. Given the chance, many species regrow from existing roots far faster than seedlings would, restoring tree cover and stabilizing soil within a few years.
- Terracing: Building stepped levels into slopes slows water runoff and captures sediment that would otherwise wash away. Terraces have been used for thousands of years in mountainous drylands and remain one of the most effective tools for preserving soil on uneven terrain.
Large-Scale Efforts: The Great Green Wall
The most ambitious restoration project currently underway is the Great Green Wall Initiative, spanning the width of Africa along the southern edge of the Sahara Desert. Its goal is to restore 100 million hectares of degraded land, sequester 250 million tons of carbon, and create 10 million green jobs by 2030. The initiative isn’t literally a wall of trees, as it’s sometimes described, but a patchwork of local restoration projects tailored to the conditions of each region: reforestation in some areas, improved farming practices in others, water harvesting systems where rainfall is most scarce.
Progress has been uneven, with some countries far ahead of others, but the initiative has drawn global funding and attention to the fact that desertification is a solvable problem. The UN estimates that the investment needed to restore degraded land is far smaller than the ongoing economic losses from doing nothing.