February 27, 2012
Desertification is defined as the deterioration of land in typically arid areas due to changes in climate and human activities. In the United States, desertification is typically caused by poor farming practices and the conversion of grazing areas to cropland. Climate change intensifies desertification in arid areas because not only are global temperatures rising and natural disasters becoming more extreme, but also the global water cycle and precipitation patterns are such that rainfall is decreasing in most areas and concentrating in a few others. Furthermore, because California is in a climactic region that can be defined as dry subtropical, the effects of climate change and agriculture has led to increased desertification. The short-term and long-term effects of this desertification are numerous and will have many repercussions for both humans and the environment.
The environmental costs of desertification are quite serious and can eventually destroy natural ecosystems. Topsoils lose their fertility and the growth and support of organic life in the pedosphere becomes much more difficult. As topsoil drys out it becomes susceptible to movement from winds, creating new natural disasters such as the Dust Bowl of the 1930’s. Furthermore, this dust can be blown out into the ocean and can affect weather patterns. In order to salvage lands affected by desertification, farmers begin to invest more in irrigation, which in turn diminishes groundwater resources and is the beginning of long-term impacts such as drought and famine. Additionally, as the topsoil becomes less nutrient rich from desertification plants become less productive and many of the ecosystem services they were providing are diminished.
Unfortunately, California becomes more susceptible to desertification there is a tendency to focus only on the immediate effects. Important long-term impacts on the environment also need to be addressed, such as the effects on the carbon cycle, biodiversity, and freshwater supply. Vegetation in arid areas stores a substantial amount of carbon (about 30 tons per hectare) and when desertification causes drought and the vegetation dies, that storage is lost. In addition, desertification dries out soil, the organic matter of which is the largest known carbon sink, resulting in increased greenhouse gas effects as that carbon is released into the atmosphere. As soils and vegetation are affected by desertification, ecosystems lose key resources that result in a loss of biodiversity. Desertification also poses a threat to freshwater resources. River flow rates decrease, leading to silt build up in estuaries, which incites saltwater intrusion into the water tables. As the demand for water increases there is a tendency to over-pump aquifers, which can result in water depletion and land compaction. For example, the San Joaquin Valley of California experienced subsidence at a maximum of 28 feet between 1925-1970 from overdrawn aquifers. Because California relies so much on agriculture, farmers exploit aquifer water for irrigation without considering these long-term issues. However, if the agricultural industry were to collapse from drought, we’d be facing the threat of famine and a huge economy crash.
Clearly there are many negative effects from the process of desertification that need to be addressed. Some of the most popular decisions to combat the effects of the land drying out include sustainable farming practices, such as drip irrigation, integrated crops, or no-till farming, and drought prevention. As stated in the 2010 California Drought Contingency Plan, “California’s water resources have been stressed by periodic drought cycles and unprecedented restrictions in water diversions from the Sacramento-San Joaquin Delta in recent years. Climate change is expected to increase extreme weather. It is not known if the current drought will abate soon or if it will persist for many years. However, it is certain that this is not the last drought that California will face.” The DCP has moved towards enhancing monitoring and early warning capabilities, assessing water shortage impacts, and creating preparedness, response, and recovery programs, which should help California to conserve water and slow down the desertification process.
Harriet Arnold and Divya Rao are undergraduates in the USC Dornsife College of Letters, Arts and Sciences.
February 14, 2012
California has always been seen as the Golden Coast. It is a land of plenty that supports millions of people and has an immense and productive agricultural industry, producing almost 15% of the nation’s annual crops.
But the productiveness of California has a limit, and both its climate and human overuse can distress the land beyond repair. Desertification is the process of the loss of nutrients (top soil) to drylands, resulting in infertile land that can be easily eroded due to the lack of vegetation that would normally provide soils with the structural component to combat erosion. Vegetation is vital to dry soils, prominent in much of the California climate, because the soils can easily be carried away by wind, or on the rare occasion of rain in Southern California, water. Over farming, which depletes the soils nutrients, or overgrazing, which physically strips the soil of vegetation, are two of the most common triggers of desertification.
Desertification can be a natural process too. The United Nations Conference to Combat Desertification identifies that desertification is also due to climactic changes, where extended periods of drought or dryness can harm vegetation and leave soil dry and exposed to the elements, although some may argue that these may be anthropogenic as because of the link between global climate change and greenhouse gas emissions.
But while desertification can be a natural process, these natural processes and tendencies of Southern California are only augmented by the anthropogenic abuse of the land such as over farming and overgrazing.
California is an extremely large and diverse state with a wide range of climate patterns and weather conditions. Therefore, while some areas are lush, others are experiencing drought. This raises the issue of distribution of water in California. About 65 percent of the state receives less than 20 inches of rain fall per year, which is indicative of the scrubland biome.  While 70 percent of California’s runoff occurs north of Sacramento, 75 percent of the agricultural demands are located in the south of the state. This is why California has undergone some of the most extensive water redistribution projects, which have created conflict over water rights between Northern and Southern California. Water supply to farmers in the far south, such as those in El Cajon, CA is still not enough, despite these water redistribution projects, to support their agricultural based economy due to the increasing water demands of Northern California.
So when Southern and Central California experience the periodic droughts indicative of their climate, the desertification that would have naturally occurred is only amplified by California’s reliance on it’s agricultural industry heavily based in the south, and it’s inability to supply the amount of water necessary for this huge, over-productive, and depleting industry.
Some political and socioeconomic implications of desertification in California include increased risk of wildfire, reduced crop yields, social unrest (water wars), and potentially dust bowl conditions similar to those that plagued the Midwest in the 1930s during the Dust Bowl. This dust creates health problems, and blows in to the ocean and other already contaminated and damaged water sources, further causing contamination.
The United Nations Convention to Combat Desertification is an initiative of the UN that hopes to remediate degraded soils through additions of fertilizers and growth of crops that do not require many nutrients, and also to fight the source of desertification. This undertaking has several objectives, including anticipating and/or limiting land degradation, repairing degraded land, raising awareness of desertification, and developing sustainable management practices through education. While droughts and the climate of Southern California cannot be controlled, and the water limitations of the area will remain a chronic issue, the best way to prevent further desertification is by cutting back overgrazing and overuse of the land, and practice farming and agricultural use in a sustainable way.
California takes specific measures of its own to combat desertification. It releases a Drought Contingency Plan every 5 years, and in 2008, the California DCP proposed new groundwater and surface water storage facilities, environmental restoration, and increased conservation and sustainable practices.
Other methods for combating desertification include water harvesting from new technologies that can extract water from the humidity in the air. Genetically Modified Organisms, or GMOs, can also be a potential solution, manufactured to be more resistant to drought and require less water, but they still pose a great deal of controversy due to other environmental factors and causes.
The fact is that desertification can only truly be diminished if the practices of the people living in the area change. Too much reliance is placed on farming in areas that cannot support the overuse, and if more sustainable farming practices do not begin soon, then the land will quickly become too unstable to even use.
Justin Bogda and Kimberly Knabel are undergraduates in the USC Dornsife College of Letters, Arts, and Sciences.
September 19, 2011
The Central Valley of California is a fertile bed of over 350 diverse species of agricultural crops, some of the major cash crops being rice, grapes, cotton, and almonds. California’s agricultural industry makes up 15% of the entire nation’s crops and made a profit of $37 billion in the year 2009.
Despite these numbers, desertification is an increasingly major problem.
Between 1998 and 2000, 10,000 acres of farmland were lost every year in Central Valley from urbanization alone—this doesn’t account for the acres of fertile farmland lost due to overgrazing, climate change, or poor farming practices. Currently, California is losing 178 km2 of arable, fertile land each year. Southern California especially, being a very arid and drought-inclined region to begin with, has a problem with increasing salinity and compound minerals in the soil, caused by overdrawing ground water (United States Geological Survey).
Desertification is not only the result of human activity. The UN Convention to Combat Desertification identifies the other major cause of desertification to be climatic variations—for example, erosion, drought and irregular rainfall, and violent winds. Essentially it renders the soil infertile, not only for planting and agriculture but for any organic life. Desertification occurs on a global scale, particularly through deforestation and drought. Areas around the Amazons, for example, have undergone desertification because the trees are being harvested for wood and cleared for farmland, and much of the space lies fallow. Similarly, in California, trees are cleared using the “slash and burn” method to open fields for cheap soybean and livestock cultivation.
Desertification is a challenge for California because it is a desert environment supporting an increasingly large population on limited water imports. The situation becomes more dire when the effects of global warming are considered, which dramatically expedite desertification. Owens Valley, California, for example, became a desert when all of the natural water resources were diverted to Southern California for drinking water and crop irrigation. The San Joaquin Valley is a region that has undergone natural desertification due to climate change, a result of surface crusting, salinization and waterlogging problems.
Most popularly considered solutions to desertification involve addressing problems of drought. Every 5 years in California a new Drought Contingency Plan (DCP) is released. In 2008, the last DCP, tactics included aggressive conservation, new groundwater and surface water storage facilities, and environmental restoration. GMOs also offer the possibility of growing crops that are resistant to drought, thus using less of the precious water resources to yield the same or greater amount of agriculture.
Similarly, Air-to-Water harvesters are a new technology that essentially takes the humidity in the air and convert it to usable water. This can slow desertification significantly.
From a more bottom-up perspective, education and conservation initiatives will also drastically reduce the human contribution to desertification. Programs teaching grey-water usage, water conservation, and the transformation of lawns into food forests can save a lot of water if it is implemented locally and broadly. Natural forests and wetlands need to be protected rather than cleared, farmed, and abandoned.
While desertification is in and of itself a natural process, the human factors can and must be reduced, especially in California, if we are to live harmoniously with the land and reap the benefits of its yield.
About the authors: Xueyou Wang and Kayla Duarte are undergraduate students in the USC Dana and David Dornsife College of Letters, Arts and Sciences.
Although not often talked about in an urgent manner, desertification is one of the most relevant and concerning environmental problems the world currently faces. It will be one of the most difficult problems to combat because of the many intricacies and challenges involved with it. The United Nations Convention to Combat Desertification defines desertification as, “land degradation in arid, semi-arid, and dry sub-humid areas resulting from various factors, including climatic variations and human activities.” A recent study evaluating desertification indicators has shown that 38% of the world’s land area is at risk of desertification. In fact it is estimated that 1 billion people are under threat if the trend of desertification continues.
With that many people at risk we have to look at what is causing the desertification and why its effects are so bad. Desertification is caused by two main factors: human interference and climate change. The human interference comes from our farming and animal grazing practices. When we overuse farming fields in dry areas the crops take nutrients from the soil faster than they can be replaced. Along with this, poor irrigation techniques remove water from the land faster than it can be replenished. Also adding to the removal of water from the land is climate change that causes higher temperatures and more/longer droughts. With less water holding the soil together erosion increases greatly, therefore removing the topsoil that is so vital to plant growth. Exacerbating this problem is overgrazing which removes plants that would usually anchor the soil and lessen the wind’s effects. All of these issues together change the soil structure leaving it sandy, saline, without nutrients, lacking biodiversity, and generally unable to support crops and animals.
Once the land has reached this level of degradation the effects are fairly obvious: without adequate food from the land some or all of the humans in the area are forced to leave or starve. In developed nations this may not seem likely because most people are not growing their own food, sustainable farming practices are available/affordable, and if worst comes to worst support systems are in place to take care of displaced people. In contrast in developing nations (especially in Africa) the opposite is true: most people grow their own food, there is no knowledge of sustainable farming practices, even if there was most practices do not make sense economically, and when people are displaced they have nowhere to go. Considering this it is shocking to know that 90% of the inhabitants of drylands live in developing countries. This means that the people most at risk from desertification have almost no resources to combat it due to poverty. As ex-UN Secretary-General Kofi Annan says, “[Desertification] is partly caused by poverty, and exacerbates it. Together with other problems, it leads to forced migration from impoverished rural areas to cities that are themselves often ill-equipped to adequately shelter and employ new arrivals.” The link between poverty and desertification is the crux of the challenge of stopping desertification. If things stay the way they are by 2020 an estimated 60 million people will be uprooted from sub-Saharan Africa and burden of the resulting refugees will be placed on the rest of the world.
The way to overcome this challenge will be through a coordinated humanitarian and environmental effort aimed at helping developing countries where desertification hits hardest. The combined effort needs to work to educate these people on desertification while also aiming to reduce poverty, therefore providing them with alternatives to unsustainable farming. This shows why desertification is such a daunting challenge because it requires revitalizing entire nations before progress can be made. The UN Convention to Combat Desertification is currently trying to do this but large scale, international initiatives need to be taken before we can even begin to combat desertification.
About the authors: Stephen Lowe is working towards his bachelors degree in Environmental Studies in the USC Dana and David Dornsife College of Letters, Arts and Sciences.