We often only begin to understand the importance of nutrient- and water-cycling when they don’t — when they don’t cycle, that is. When ecosystems fail, when the hydrological cycle gets broken, when soils degrade faster than they build, the consequence is desertification. Already a full 25% of the planet’s land surface area (about 3.6 billion hectares) is desertified, and, worldwide, we’re adding to this enormous figure at a rate of 12 million hectares annually. And this rate is increasing.
More than ever before, we now understand the mechanisms behind desertification. Even just one lifetime ago we thought we were too small, and the world too large, for us to have any real effect on planetary functions, but that has all changed. Today we know that we are having a profoundly negative impact on the earth’s systems — those systems upon which all life, and all economic activity, depend — and we’re also learning that reversing that impact is a lot harder, and a lot more time-consuming and expensive, than preventative measures to avoid it in the first place.
Today entire towns and villages sit precariously under threat as sand dunes the size of large buildings threaten to overrun them. People are being relocated away from these front lines, placing additional ecological pressure on the areas they move to. Most villagers do not understand what brought this war to them, and so can’t conceive how to fight back.
In the video above, John D. Liu takes us to one of these front lines — the growing deserts of China — and shares some examples of how people are learning from their mistakes and working to reverse their consequences. In a great many parts of the world, we need to draw a line in the sand and say "no more". With populations growing, and pressure on available resources becoming acute, there is no time like the present to make an all-out assault on the front lines of the world’s great deserts. We know it can be done. We know it needs to be done. We must just find a way to reinvent our economies to accommodate this stark reality. We have to find a way to foot the bill.
And more, for the billions of hectares of agricultural land currently under the plough, it’s important farmers come to understand what they will face if we don’t learn to manage our soils according to nature’s principles of give and take. At the moment we’re making withdrawals faster than deposits — operating the balance sheet from hell. Desertification creates negative feedback loops that make reversal exponentially more challenging than prevention.
Desertification occurs when the tree and plant cover that binds the soil is removed. It occurs when trees and bushes are stripped away for fuelwood and timber, or to clear land for cultivation. It occurs when animals eat away grasses and erode topsoil with their hooves. It occurs when intensive farming depletes the nutrients in the soil. Wind and water erosion aggravate the damage, carrying away topsoil and leaving behind a highly infertile mix of dust and sand. It is the combination of these factors that transforms degraded land into desert.
There are many factors that contribute to desertification. Prolonged periods of drought can take a severe toll on the land. Conflict can force people to move into environmentally fragile areas, putting undue pressure on the land. Mining can cause damage. In the coming years, climate change will accelerate the rate of desertification in some areas, such as the drier areas of Latin America.
The effects of desertification can be devastating. Desertification reduces the land’s resilience to natural variations in climate. It disrupts the natural cycle of water and nutrients. It intensifies strong winds and wildfires. The effects of dust storms and the sedimentation of water bodies can be felt thousands of kilometres away from where the problems originated.
The cost of desertification is high, and not just in economic terms. Desertification is a threat to biodiversity. It can lead to prolonged episodes of famine in countries that are already impoverished and cannot sustain large agricultural losses. Poor rural people who depend on the land for survival are often forced to migrate or face starvation.
Desertification not only means hunger and death in the developing world, it also increases threats to global security for everyone. War, social disorder, political instability and migration can all result from scarce resources. For millions of people, halting desertification is a matter of life and death.
Desertification is not always inevitable. Human factors, such as overgrazing and clear-cutting of land, can be controlled by improving agricultural and grazing practices. Other factors, such as rising temperatures, can be predicted and dealt with proactively. Degraded land can sometimes be rehabilitated and its fertility restored. In many cases, the best methods of rehabilitating land involve using traditional or indigenous knowledge and land management techniques. But rehabilitation efforts can fail or eventually have a negative impact on ecosystems, human well-being and poverty reduction. It is less costly, and less risky, to limit the damage in the first place. — IFAD