Explaining desertification: natural causes and human contribution

By Daniil Filipenco

Explaining desertification: natural causes and human contribution

Desertification is considered to be among the biggest problems facing humanity today. It occurs not only due to environmental phenomena such as drought and extreme weather events but also because of human activities such as deforestation. The impact of desertification when combined with droughts and a decrease in agricultural outputs cannot be ignored.

What is desertification?

Desertification refers to continuous pervasive land degradation in a certain area as a result of natural or manmade causes whereby the productivity of dryland ecosystems is lowered, plant cover is diminished, organic soil matter is eradicated, and the expanse of sand dunes grows.

Desertification typically occurs in regions with low or unpredictable rainfall. However, it also happens in other regions where humans play a part through practices such as excessive deforestation.

What causes desertification?

Although desertification has been primarily blamed on human activities over the last few decades, environmental factors are sometimes completely or partially to blame, often serving as a catalyst.

Climate change and human activities are causing many drylands to quickly degrade. Desertification is another term for this degradation, mainly occurring in drylands.

The Earth’s drylands cover nearly 40% of land surface

Source: Carbon Brief

Human contribution to desertification

Although there are several causes of desertification, humankind has greatly contributed to this through unsustainable land use. The most frequently mentioned examples of human contribution include:

🔹 Deforestation

This refers to the deliberate clearance of a forest or trees so the ground can be put to another use other than being a forested area. This leads to the bare ground becoming much hotter and dryer because, without flora, processes such as evapotranspiration are no longer possible.

When trees are cut down, their roots are also lost and therefore rain and wind are more likely to wash or sweep away the soil.

🔹 Overgrazing

Overgrazing happens when livestock consumes more plant biomass than the vegetation is able to replenish in a reasonable amount of time, exposing the soil and lowering the vegetation’s production potential.

Since animals will sometimes devour plants right down to the roots and eat seeds, this prevents these from regrowing. Wide, open spaces are therefore created and the soil becomes susceptible to erosion and moisture loss.

🔹 Inefficient farming methods

Overcultivation (too much farming of the same area of land) and monocropping (planting the same crop every year) can harm the health of the soil by preventing it from having sufficient time to recover its nutrients.

Excessive soil tilling (disturbing the soil too often or too deeply) can also affect the goodness of the land causing it to dry up too quickly. Topsoil loss begins to outweigh replacement soil after a few years of repeated tillage because the soil loses organic matter and nutrients.

🔹 Poor water management

In rural and urban areas, including popular tourist destinations, large amounts of groundwater are drawn from natural aquifers, preventing these from naturally replenishing which leads to eventual water scarcity.

Environmental factors leading to desertification

🔹 Soil erosion

All landforms are impacted by the naturally occurring phenomenon of soil erosion. In agriculture, this is the process that involves a field’s topsoil being worn away by water and wind. It can also occur as a result of farming practices such as tillage but one major cause of soil erosion is the transformation of forests into cropland.

🔹 Drought

Droughts, extended intervals of time with minimal rainfall, could speed up desertification causing an even more serious shortage of water and accelerating soil erosion. Plants are unable to survive without sufficient water and thus die out, leaving the soil more vulnerable to wind erosion.

🔹 Wildfires

Massive forest fires cause desertification by destroying plant life and drying out the soil, leaving the area more vulnerable to erosion, and allowing the spread of non-native species after the burnt ground has been reseeded. Invasive species are much more prevalent in burnt areas than on unburnt land and this significantly reduces biodiversity.

🔹 Climate change

While we know that the average air temperature on Earth is rising, the temperature on land rises faster than it does in the atmosphere and although human activity is one of the causes of land warming, extreme weather events play their part too.

The impacts of land warming include:

  • Vegetation suffers from heat stress.
  • Severe rainfall and droughts cause soil degradation, exacerbating current issues with poverty and forced migration.
  • The breakdown of the soil’s organic matter is accelerated by a warmer environment, stripping the soil of nutrients.

Final word

Recurrent droughts, a lack of rain, soil erosion, and other harsh climate events are all natural causes of desertification that are being exacerbated by global warming with humankind being the main contributor to this. Desertification actually endangers biodiversity and impedes development since the land becomes useless and illnesses and famine begin to spread. Almost 2 billion people today reside in drylands and this could lead to 50 million individuals being displaced by desertification by 2030.