Why fertile land is turning to desert

Nearly one half of the planet's land mass is on the brink of turning into nonarable desert, according to the United Nations Convention to Combat Desertification (UNCCD).

These already-arid lands are marked by low rainfall yet support 45% of the world's agriculture. Now, extreme drought linked to human-made global heating is helping to transform this area into an infertile wasteland.

With one in three of the world's people living in these drylands, experts say that food insecurity, poverty, and mass displacement will accompany desertification.  

The problem is so severe that a United Nations desertification conference (COP16) happening in Saudi Arabia in December is demanding that 1.5 billion hectares of the world's desertified land be restored by 2030. This is the area the UN says could be rehabilitated.

What is desertification?

Desertification is a form of land degradation by which fertile land loses much of its biological — and economic — productivity, and becomes desert.

Today, up to 40% of the world's land is already degraded, according to the UNCCD.

While climate change, deforestation, overgrazing, unsustainable agricultural practices, and urban sprawl are key factors in desertification, a global drought crisis is exacerbating the problem.

Extreme drought and heat drives water scarcity and leads to soil degradation and the loss of crops and vegetation.

With 2024 set to be the hottest year on record, drought could impact 75% of the world's population by 2050, according to a UN report released on Tuesday.

Water scarcity further aggravates the impacts of deforestation. And fewer trees means fewer roots to bind the soil, thereby preventing erosion.

Meanwhile, social issues such as limiting women's ability to own land can also impact land and soil health. The UN notes that women more often invest in biodiverse food systems — as opposed to men who mostly focus on high-yielding monocultures that can quickly degrade land.

Why does desertification matter?

Severe land degradation and desertification are impacting the Earth's ability to "support environmental and human wellbeing," said a 2024 UNCCD report.

Degraded land can no longer support diverse ecosystems, or help regulate climate, water flows, and the production of nutrients vital for all life on the planet.

Healthy land also provides food security and a sustainable agricultural system, says the study.

But with so much fertile, productive land degraded each year, ongoing desertification is instead accelerating biodiversity loss, hunger and poverty.

Forced migration and conflicts over declining resources will be some of the further consequences. 

"It is the land and soil beneath our feet that grows the cotton for the clothes we wear, secures the food on our plates, and anchors the economies we rely on," noted Ibrahim Thiaw, executive secretary of the UNCCD.

What can be done about desertification?

A key theme of efforts to combat desertification is soil restoration and the promotion of more sustainable, "nature-positive" agriculture and grazing management, according to Susan Gardner, director of the ecosystems division at the United Nations Environment Programme (UNEP).

This goes hand-in-hand with the conservation of "watersheds" that store water.

The UN World Food Programme, for example, has been working to improve water resilience in Mauritania and Niger in western Africa by building "half-moons" that retain rainwater.

The semi-circular ponds help degraded soils to hold water for longer and to support vegetation. And they are practical and economical for the local population to build.

But more drastic measures are also being taken to stop the spread of deserts.

Back in 2007, nations in the Sahel region of Africa decided to stop the southward spread of the Sahara Desert to the north — fuelled by drought and climate change — by nurturing trees, grasslands, and vegetation to create The Great Green Wall.

Billions of trees were to be planted across nearly 8,000 kilometers (4,970 miles) from the West to East African coasts to create buffer zones to prevent further desertification.

According to the latest UN figures, a fifth of the targeted restoration has been achieved with progress stalled due to a lack of funding. Nonetheless, new initiatives are pushing forward to green 100 million hectares of degraded land across Africa.

A similar replanting initiative in China and Mongolia's Gobi desert, also known as the "Great Green Wall," includes efforts to reduce overgrazing among Mongolian herders.

Nearly 80% of Mongolian land was affected by degradation by 2020, and a UN initiative has sought to combat desertification through sustainable land management — including protecting nearly 850,000 hectares in the southern Gobi region as biodiversity corridors.

Edited by: Tamsin Walker