The human-induced degradation of arid, semi-arid, or sub-humid land (collectively known as dryland) and loss of vegetative cover are termed Desertification. The term might have pulled out a Sahara Desert sketch or any other desert in your mind. However, it is not limited to one. It encompasses all the changes in soil quality, vegetative cover, water resources, wildlife, and land-use changes.
The United Nations Convention to Combat Desertification (UNCCD), established by the United Nations in 1994, defines drylands as “areas other than polar and sub-polar regions where the ratio of annual precipitation to potential evapotranspiration ranges between 0.05 to 0.65 or 5% to 65%”. Desertification hardly hits the drylands as these regions receive little or no annual precipitation.
About 46.2% of the Earth’s total land area is dryland, ranging from Africa, western North America, Australia, Middle East, and Asia. About 3 billion people inhabit these regions that are directly affected by desertification.
Desertification reduces agricultural productivity, biodiversity, and incomes and increases invasive species that can disrupt ecosystems. The over-extraction of the water is depleting underground resources.
Coupled with unsustainable land management and droughts, it is stirring up sand storms that can be impervious to human health. The loss of livelihood is leading to mass immigration. According to UNCCD, desertification would be responsible for 135 million displaced people by 2045.
According to the United Nations, the rate of desertification has aggravated 35 times. Desertification is a significant concern in the developing countries of the World. More than 100 countries are vulnerable to desertification. Particularly the poorest ones located at the edge of the Sahara desert as Africa are hit hard.
65% of Africa is dryland, of which 75% is uninhabited. They experience recurring devastating droughts. Desertification is placing stress on the expanding population by declining productivity.
Driving Factors of Desertification
The driving factors include sprouting populations, urbanization, substantial resource extraction, mining, farming, overgrazing, deforestation, and all the activities aspired by human beings’ insatiable desires.
Climate change also magnifies the impact with variations in temperatures and precipitation rate and increased risk of droughts. 2 degree Celsius rises in temperature could lead to the aridification of 30% of the Earth’s landmass. All these events affect the soil’s water retention and nutrient cycling capacity and contribute to soil erosion.
Although overlapping, the drivers vary with geographical locations. The blooming population in Africa, the second largest population in the World, increasing at a rate of 2.49%, led to extensive wood harvesting and land-use changes that burgeoned desertification. It, in turn, has now reduced productivity. Thus, degraded or deserted lands can no longer support populations, leading to malnutrition, diseases, and mass immigration.
Causes of Desertification
The cross-cutting causes of desertification can be broadly classified into;
1- Land Management
2- Climate Change
Desertification and Land Management
Land Management encompasses deforestation, overgrazing, unsustainable farming, and irrigation practices that can degrade the land.
The increasing human population is the root cause of many evils. 50% of the forest trees are bulldozed. The land is cleared to accommodate 7.8 billion living beings and compensate for the demand for food and quality living standards.
Green matter plays a vital role in holding moisture and providing stability to soil. It is also responsible for the water cycle and annual rainfall. And we are promoting desertification by converting the green biomes to drylands.
An increasing number of animals lead to extensive grazing. Animals feast the plant to the ground and trample the roots, thus contributing to the topsoil removal with rainfall. It hardens the soil, thus hindering plant re-growth. Overgrazing has converted many vegetative lands into desert biomes.
c- Farming Practices
There have been numerous technological advancements in farming and agricultural practices to optimize crop yields and demands. However, this intensification is also disturbing the soil nutrient cycle. The extensive use of fertilizers is adding insult to injury. They are causing soil salination and acidification, decreasing fertility in the long run.
While the farming practices have depleted soil of its nutrients and organic carbon, they have also resulted in over-drafting underground water for irrigation. Over extraction of water resources leads to desertification.
d- Stripping the Land of Resources
Mining of land resources for valuable gems and materials is another leading cause of desertification. Several mining operations pose a serious threat to the ecosystem by polluting local water bodies and soils. It significantly changes the physical and chemical makeup of the environment that leads to soil acidification and desertification.
Desertification and Climate Change
The human-induced climatic variations in increased land surface temperature, evapotranspiration, and decreased precipitation are also involved in desertification. Land temperatures have substantially increased by 1.7 degrees Celsius compared to the 1.1 degree Celsius rise of average global temperature. This climatic variability coupled with cropland expansion, unsustainable land management, and increasing population pressures affects precipitation; low levels aggravate desertification. The rainfall cools the land surface; the temperature rise is drying out the soils and causing soil erosion--removing the land surface’s topsoil.
With increasing temperatures, droughts are also a common occurrence that promotes drylands. The widespread lack of Sahel, Africa is attributed to climatic variations in the Atlantic, Pacific, and Indian Oceans.
The bare, dry soils also add dust particles into the atmosphere with dust or sand storms that reflect the incoming solar radiations. This may significantly reduce the surface temperatures but raise the temperature of the air above. Hence, it is affecting the cloud formation and precipitation in drylands. Other impacts of sand storms include respiratory diseases, skin irritations, and infrastructural damages.
Soil respiration is when soil microbes decompose the organic content and produce CO2 to regulate the plant’s growth. It is regulated by soil moisture content. The warmer temperatures promote carbon dioxide fertilization (by the decomposition of soil organic matter) and enhance vegetation. Each gram of organic matter can hold up to 20 grams of soil moisture.
But, decreased water availability reduces soil respiration and increasing aridity. With the diminished ability of arid soils to mineralize carbon with soil respiration, carbon sequestration and plant growth are negatively impacted.
Desertification is altering the green cover of the ecosystem and influencing the native wildlife. Wildlife have not adapted to the cumulative effects of climate change and desertification. Thus it is thinning out in desertification-prone regions. The invasion of drought-tolerant species is another primary concern.
According to UNCCD, they estimate desertification dries up 12 million hectares of productive land per year. In many East African countries, food security and GDP depend on the vegetative cover. 40% of Somalia’s GDP is contributed by livestock alone. The decreased productivity is responsible for declining livestock population and food security. People are forced to survive by skipping meals or immigration.
All the factors that work in association with other human drivers worsen the desertification process. Desertification not only decreases crop and livestock productivity, biodiversity or induces wildfires, but it also affects food security and livelihood in developing countries, says Dr. Alisher Mirzabaev, a coordinating lead author on the desertification chapter of the IPCC report.
How to Prevent Desertification
Desertification is the product of imbalance in the ecosystem’s demand and supply. With the increasing population, there is an insatiable pressure on drylands for food, forage, water, and other ecosystem services. Coupled with climate change, reduction in water table and drought leads to a substantial green cover decrease.
Rangeland management and restoration are crucial as pastoralists depend on the dryland resources for animal feed and livelihood. Integrated land and water management is a promising approach against erosion, salinization, and land degradation. Vegetative cover is the best barrier against soil erosion. Land use can be optimized for grazing and farming to ensure nutrient cycling.
Soil reclamation with natural fertilizers (manure and compost) is another viable option to enhance nutrient cycling and prevent desertification. Water management with drip irrigation would be a bonus.
Yet, the simplest inexpensive solution to combat desertification is planting trees. The trees hold the soil particles in place that keeps the moisture and organic matter. Therefore, reduces the channeling of nutrients with erosion.
Global efforts to Combat Desertification
The Convention to Combat Desertification (UNCCD) was established by the UN in 1994 to address desertification. United Nations celebrated 2010-2020 as the Decade for the Deserts and Fight against Desertification. The 2020 theme for World Day to Combat Desertification and Drought was Food, Feed, and Fiber. It highlights the ecosystem’s pressures to provide food, animal feed, and fiber for urban communities’ clothes while productivity decreases. The slogan was aimed to educate people to reduce their global impacts by changing lifestyles.
The Sahara is the warmest desert in the World. The semi-arid Sahel is the transitional zone between Sahara and Savannah. The retreat of Sahel has expanded the Sahara desert southward by 16 percent. Lake Chad is hit hardest with desertification. The decreased annual precipitation and extensive groundwater pumping have dried up the lakes and displaced millions of people. At the same time, 70 percent of Ethiopia is vulnerable to desertification.
The Great Green Wall Initiative is an 8 billion dollar restoration program of UNCCD in collaboration with the African Union. The 8000 km long and 50km wide green belt was proposed by a British forester Richard St. Barbe Baker.
The projects aim to restore 100 million hectares of arid or degraded land. Initially aimed at tree plantation, the project has broadened its vision to provide food security, climate resilience, and economic growth opportunities across 20 Sahel-Sahara countries of Africa.
Another great initiative is of World Bank in Ningxia, northwestern China, to control desertification. China has been fighting desertification for six decades. The project entails the sand dunes fixation with a 1+4 approach. This restored the vegetative cover by 40%. The project has not only improved the environment but also provided alternate livelihood options for the local community. These include the growth of desert chives, calcium fruits, sand fixing shrub Caragana that is also an excellent fodder source, and the making of straw checkerboards, to name a few.
We need more integrated land and water or rangeland management programs that combat desertification and provide alternate livelihood opportunities to satiate the hunger and improve the living standards.
Nida Riaz is a freelance blogger based in Pakistan. She started writing about her passion for the environment when the world came to a stop in early 2020.