Desertification: A Global Problem Affecting All of Us
This discussion is a compilation of excerpts from the Millennium Ecosystem Assessment on Desertification Synthesis, The United Nations Convention to Combat Desertification, and Green Facts.
Desertification, a fancy word with a rather simplistic definition has dire consequences for all of humanity the world over. Desertification is defined by the U.N. Convention to Combat Desertification as “land degraded in arid, semiarid and dry subhumid areas resulting from various factors, including climatic variation and humid activities.” Land degradation is in turn defined as the reduction or loss of biological or economic productivity of once arable drylands.
The Young People’s Trust for the Environment gave this closer to home view of desertification: “It has been said that forests came before human beings, deserts followed them. Desertification is becoming a major problem as more and more of the world’s land surface is turned into desert. The new deserts which are being created are not necessarily hot, dry sandy places, but are instead any areas where the soil has been so mistreated by humans that it is now useless for growing crops. You may think that this doesn’t affect us here in Britain, after all, it’s too wet and cold for a desert to be formed here. That may be true, but that doesn’t mean that desertification won’t affect us. Think about it. If our soil is not conserved, then our food supply and all our lives are threatened.”
Additionally, “Desertification has environmental impacts that go beyond the areas directly affected. For instance, loss of vegetation can increase the formation of large dust clouds that can cause health problems in more densely populated areas, thousands of kilometers away. Moreover, the social and political impacts of desertification also reach non-dryland areas. For example, human migrations from drylands to cities and other countries can harm political and economic stability.”
The following map shows the major components of biodiversity loss (in green) directly affect major dryland services (in bold). The inner loops connect desertification to biodiversity loss and climate change through soil erosion. The outer loop interrelates biodiversity loss and climate change. On the top section of the outer loop, reduced primary production and microbial activity reduce carbon sequestration and contribute to global warming. On the bottom section of the outer loop, global warming increases evapotranspiration, thus adversely affecting biodiversity; changes in community structure and diversity are also expected because different species will react differently to the elevated CO2 concentrations.
Linkages and Feedback Loops among Desertification, Global Climate Change, and Biodiversity Loss
Desertification “occurs on all continents except Antarctica and affects the livelihoods of millions of people, including a large proportion of the poor in drylands. Home to a third of the human population in 2000, drylands occupy nearly half of Earth’s land area. Across the world, desertification affects the livelihoods of millions of people who rely on the benefits that dryland ecosystems can provide.”
The Millennium Ecosystem Assessment on Desertification Synthesis suggests “35% of the earth’s land surface is at risk, and the livelihoods of 850 million people are directly affected. 75% of the world’s drier lands are affected by desertification, and every year 23,000 sq. miles of agricultural land are lost and become virtual desert. It follows that based on the total number of people threatened by desertification, this ranks among the greatest contemporary environmental problems with serious local and global impacts.”
Most of the endangered dryland regions lie near the world’s five main desert areas:
• The Sonoran Desert of northwest Mexico and its continuation into the southwest United States;
• The Atacama Desert, a thin coastal strip in South America between the Andes and the Pacific Ocean;
• A large desert area running eastward from the Atlantic Ocean to China, including the Sahara desert, the Arabian Desert, the deserts of Iran and the former Soviet Union, the Great Indian Desert (Thar) in Rajasthan, and the Takla-makan and Gobi Deserts in China and Mongolia;
• The Kalahari Desert in southern Africa; and
• Most of Australia.
There are some other areas of major concern:
• In Africa, 66 per cent of the total land area is arid or semi-arid; in North America, the figure is 34%.
• About 40% of the continental United States is considered vulnerable to desertification by the US Bureau of Land Management. At least 40% of Texas pasture land is already too parched for grazing.
• Drylands cover more than a third of the earth’s total land surface, while deserts account for about 7%. Activities to counter desertification focus on preventing the creation of “desert-like conditions” in dryland areas.
• The Roman Empire’s breadbasket in North Africa, which once contained 600 cities, is now a desert.
Desertification “is caused by a combination of social, political, economic, and natural factors that change over time and vary by location. These include indirect factors such as population pressure, socioeconomic and policy factors, and international trade as well as direct factors such as land use patterns and practices and climate-related processes.” Specifically:
• Policies that can lead to an unsustainable use of resources and lack of infrastructures are major contributors to land degradation. Agriculture can play either a positive or a negative role, depending on how it is managed. Policies favoring sedentary farming over nomadic herding in regions more suited to grazing can contribute to desertification.
• The process of globalization both contributes to desertification and helps prevent it. Studies have shown that, in some cases, trade liberalization, economic reforms, and export-oriented production in drylands can promote desertification. In other cases, enlarged markets outside of the drylands also contribute to successful agricultural improvements.
• Historically, dryland livelihoods have been based on a mixture of hunting, gathering, farming, herding and deforestation. This mixture varied with time, place, and culture, since the harsh conditions forced people to be flexible in land use. Population growth has led to the extension of cultivated lands and the irrigation of these lands has brought about desertification, as well as other environmental problems
In closing, these factors lead to decreased land productivity and a downward spiral of degradation and poverty. In addition to its negative economic and environmental impacts, desertification is partially responsible for population migration. Poverty forces poor people to wring as much as possible from the land in order to feed, house and warm their families. Unfortunately, over-cultivation, deforestation and other unsustainable practices degrade the land, forcing people to look elsewhere to support themselves. Desertification has played a part in armed conflict in arid lands, having contributed to political instability, starvation and social breakdown in places such as Somalia.
The next discussion will discuss ways to combat desertification.