Desertification: meaning, causes, consequences and solutions

What does desertification mean?

Desertification means the degradation of land in arid, semi-arid and dry sub-humid areas, caused by human activities and climatic variations — the official definition adopted by the UN Convention to Combat Desertification (UNCCD) in 1994. It is not the natural spread of existing deserts: it is once-fertile land losing its biological and economic productivity, usually through soil erosion, loss of vegetation and depleted water sources.

The scale is staggering: the UN estimates that up to 40% of the world's land is already degraded and that another 100 million hectares of healthy, productive land — an area larger than Egypt — are degraded every year. Land degradation directly harms around 3.2 billion people, roughly 40% of the global population, above all rural communities, smallholder farmers and the poorest households.

Causes of desertification

Natural factors play a role, but most of today's desertification is attributable to human activity. Four main drivers explain the degradation of the world's drylands: overgrazing and overexploitation of the soil, deforestation, poorly managed intensive farming and irrigation, and climate change.

Overgrazing and overexploitation

Overgrazing is one of the most widespread direct causes: when too many livestock graze the same land, vegetation has no time to recover, the soil is left bare and wind and rain strip it away. This is a central issue across African rangelands, from the Sahel to the communal grazing lands of South Africa. Added to it is the overexploitation of the land itself: continuous cropping without fallow periods that exhausts soil nutrients, fuelwood harvesting that removes the plant cover, and activities such as mining that destroy the soil outright.

Deforestation

Trees anchor the soil with their roots, enrich it with organic matter, store carbon dioxide and hold moisture in the landscape. Deforestation breaks that balance: without forest cover, the land is exposed to erosion, loses fertility and can end up as barren ground. It is one of the fastest routes to desertification, especially in dry tropical regions where trees are cut for fuelwood and charcoal.

Intensive farming and poorly managed irrigation

Intensive agriculture degrades the soil when it ignores the land's natural rhythms: monocultures that impoverish the earth, heavy machinery that compacts it, and the absence of crop rotation. Poorly managed irrigation is especially damaging in dry areas: excessive pumping depletes the water table, while irrigating without proper drainage causes salinisation — a build-up of salt that renders soils unproductive. Organic farming and efficient irrigation are the sustainable alternatives.

Climate change

Global warming, driven by greenhouse gas emissions, multiplies the extreme weather events that accelerate desertification: longer and more frequent droughts, heatwaves, torrential rain that washes away bare soil, and higher evaporation of the water that remains. In its 2019 special report on climate change and land, the IPCC underlined the essential role of land in the climate system: degraded soils store less carbon, which in turn worsens climate change. It is a vicious circle.

Effects of desertification

More than 2 billion people live in the world's drylands and depend on their ecosystems. When that land degrades, the consequences cascade through food supplies, water, migration, biodiversity and health.

Food insecurity and poverty

Degraded land produces less. According to the UNCCD, the 12 million hectares lost every year to desertification and drought alone represent the lost opportunity to grow 20 million tonnes of grain. The result is more hunger, deeper rural poverty and more volatile food prices — precisely in the regions least able to absorb them.

Water scarcity

Healthy soil works like a sponge, absorbing rainfall and recharging aquifers. Desertified soil lets water run off without retaining it. Desertification therefore deepens water scarcity: less water to drink, to irrigate crops and to water livestock, and groundwater that is increasingly depleted and salinised — a familiar pattern from the Sahel to drought-hit provinces of South Africa.

Forced migration

When the land can no longer sustain them, people move. The UNCCD estimates that 135 million people could be displaced by 2045 because of desertification. These migrations also fuel geopolitical tension and conflict over resources — water, pasture, arable land — as is already happening across the Sahel.

Biodiversity and carbon loss

Drylands host unique ecosystems adapted to aridity — think of the succulent flora of South Africa's Karoo. Degradation destroys habitats and pushes species towards extinction. Degraded soils also release the carbon they stored and lose the capacity to capture more, feeding global warming and closing the vicious circle between desertification and climate change.

Sand and dust storms

Bare, degraded soils are the main source of sand and dust storms: the UN estimates that around 2 billion tonnes of sand and dust enter the atmosphere every year. These storms damage crops and infrastructure and cause respiratory and cardiovascular problems thousands of kilometres from where they start.

Where does desertification happen?

Drylands cover around 40% of the Earth's land surface, so desertification touches more than 100 countries on every continent. Africa is the most exposed of all: roughly 45% of the continent's land area is affected by desertification, and around 65% of its productive land is degraded to some degree.

The Sahel

The Sahel, the semi-arid belt stretching across Africa just south of the Sahara, is the global symbol of desertification. A combination of recurrent drought, rapid population growth, overgrazing and fuelwood cutting has dried out and stripped the topsoil across millions of hectares, feeding poverty, hunger and migration. UN agencies estimate that Africa loses around 280 million tonnes of cereal crops every year from 105 million hectares of degraded cropland. In response, the countries of the region launched the Great Green Wall in 2007 — an 8,000 km mosaic of restored land from Senegal to Djibouti, covered in detail below.

Southern Africa and the Karoo

Desertification is not only a Sahelian story. According to South Africa's National Action Programme to combat desertification, about 91% of South Africa is drylands — arid, semi-arid or dry sub-humid land vulnerable to degradation. Long-term research in the semi-arid Karoo shows that the most severe degradation is concentrated where grazing pressure is highest, particularly on communal rangelands along the escarpment, where overstocking, soil erosion and bush encroachment reduce the land's carrying capacity.

Recurrent droughts — such as those that hit the Eastern Cape, Northern Cape and Western Cape in recent years — compound the problem across Southern Africa, from Namibia's rangelands to southern Zimbabwe and Botswana. For the region, combating land degradation is inseparable from water security, food security and rural livelihoods.

Asia: China and Central Asia

Desertification has long been a huge problem in China, where the World Bank estimates more than a quarter of the population is affected. In the Ningxia Hui region, overgrazing eroded the topsoil until more than 55% of the land was vulnerable to desertification and sandstorms were routine. A restoration drive between 2012 and 2020 delivered striking results, according to the World Bank:

• vegetation restoration and natural regeneration recovered 32,500 hectares of land;
• vegetation cover increased by 28%, with a greater variety of species;
• more than 8,000 jobs were created, for example forestry workers tending plants and trees;
• the number of days lost to windblown sand fell by 25%, from 12 to 9.

Central Asia offers the starkest cautionary tale: the shrinking of the Aral Sea, caused by decades of poorly managed irrigation, turned a vast inland sea into a salt desert.

The Mediterranean and Europe

Spain is the European country at greatest risk: around three quarters of its territory is arid, semi-arid or dry sub-humid land susceptible to desertification, aggravated by repeated forest fires, aquifer overexploitation and intensive irrigated agriculture. Even the UK is not immune to land degradation: intensive farming practices such as deep ploughing degrade agricultural soils in regions like East Anglia, and according to theconversation.com the country has just 13% forest cover, one of the lowest levels in Europe.

The Americas and Australia

In Mexico, 65% of the national territory is drylands and nearly half the country suffers some degree of soil degradation. Further south, the semi-arid northeast of Brazil was the first arid zone of that country officially recognised as undergoing desertification, while Australia's rangelands face chronic degradation from overgrazing and drought.

The UN data: the UNCCD and COP16

The international fight is organised around the UNCCD, adopted in 1994 and ratified by 197 parties. Its roadmap is summed up in Sustainable Development Goal 15, which sets the target of land degradation neutrality by 2030.

Sustainably manage forests, combat desertification, halt and reverse land degradation, halt biodiversity loss. - Goal 15: Life on land

The UNCCD COP16, held in Riyadh (Saudi Arabia) in December 2024, was the largest UN land conference to date, and its figures now set the agenda. The UN calculates that $2.6 trillion of investment is needed by 2030 — around $1 billion a day — to restore more than 1 billion hectares of degraded land and build resilience to drought. In Riyadh, $12.15 billion was mobilised for the Riyadh Drought Resilience Partnership, aimed at the 80 most vulnerable countries. Agreement on a binding global drought regime was deferred to COP17 in Mongolia, in August 2026.

How to stop desertification

Desertification is reversible if action comes in time. The solutions combine prevention (using the land without exhausting it) with the restoration of land already degraded — and they rank among the most cost-effective climate investments: every dollar spent restoring land returns several dollars in ecosystem and agricultural benefits.

Sustainable land management

The first line of defence is managing land that is still productive:

• crop rotation and fallow periods so the soil can regenerate;
• matching stocking rates to the land and rotational grazing to prevent overgrazing;
• efficient irrigation (drip systems, water reuse) that avoids salinisation and aquifer depletion;
• agroforestry: integrating trees into crops and pasture to anchor the soil and provide shade;
• developing renewable energies (solar, wind and biogas) to replace wood as a fuel source;
• involving and educating local communities, who manage the land day to day.

Restoration and reforestation

Restoring degraded land goes beyond planting trees: it means rebuilding the ecosystem with native, drought-adapted species, reconstructing terraces and water-retention structures, and protecting natural regeneration. It is central to sustainable development and to the energy transition in developing countries. Individuals can contribute too: since 2019, Selectra has enabled people to offset their carbon emissions through clean energy projects such as the Gandhi wind farm in India.

The Great Green Wall of Africa

The Great Green Wall is the world's most ambitious restoration initiative: a mosaic of restored landscapes some 8,000 km long, from Senegal to Djibouti across the Sahel, driven by 22 African countries. Its 2030 goal is to restore 100 million hectares, sequester 250 million tonnes of carbon and create 10 million green jobs. Progress is real but behind schedule: estimates put the area restored so far at between 18 and 30 million hectares, well short of the pace required — which is why COP16 mobilised fresh funding to accelerate the roll-out.

Land degradation neutrality (LDN)

Land degradation neutrality (LDN) is the framework guiding national action: by 2030, every hectare that is degraded must be compensated by restoring an equivalent area, so the net balance of healthy land never falls. More than 130 countries — including South Africa — have already set national LDN targets with the UNCCD. It is the piece that connects the fight against desertification to sustainable development and climate action.

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