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.
September 12, 2011
Water supply in California’s Sierra Nevada range is primarily determined by seasonal precipitation, which occurs for the most part in the fall and winter seasons. The runoff from this precipitation provides substantial flow during spring snowmelt for animals, plants and humans. Through various measurements taken by various stations posted throughout the Sierra mountain range, it is evident that annual snowfall and precipitation has decreased and will continue to do so as climate change and anthropogenic influences heat the earth (Hall and Kapnick 2010). The decreases in snowmelt coupled with anthropogenic influences in the Sierras are posing many abiotic and biotic pressures on plants and animals living in the region and many are on the verge of extinction. Home to 135 threatened plant species and providing “as much as 65 percent of California’s water supply”, the Sierra mountain range remains a crucial habitat for humans, animal and plant species.
Decreased snow melt and anthropogenic influences, such as the introduction of non native species to the Sierra Nevada’s water sources, have posed a serious threat to species such as the Sierra Nevada yellow-legged frog or Rana sierrae, which are native to the area. The Rana sierrae relies on perennial sources of water in order to survive into adulthood, but with the introduction of trout, which prey on Rana sierrae in all three stages of their life, into deeper bodies of water, the Rana sierrae has had to rely on inferior and shallower fishless water sources, which often times run dry in the summer due to decreased snow melt and climate change (Mathews and Preisler 2010). As climate change and anthropogenic influences encroach on the Rana sierra’s habitat, they will eventually become extinct in the region and thereby decrease the rich biodiversity.
Unfortunately, other species inhabiting the Sierra Mountains are reacting more severely to increased temperatures than scientists had anticipated. “What surprised us are how sensitive these trees are to short-term changes in climate,” says U.S. Geological Survey’s Phillip van Mantgem, who conducted a study measuring the mortality rate of Sierra’s coniferous species. Beginning in 1983, Mantgem found that by 2007 the death rate had nearly doubled. The conifer’s lower survival rates can greatly be attributed to increased temperatures. The Sierra Forest Legacy notes that during a recent 22-year period, “the Sierra Nevada warmed by 1.8 degrees Fahrenheit”. Despite no apparent fluctuation in the average precipitation during this 22-year period, increased temperatures have led to higher evaporation rates creating dryer soil conditions. The University of California Santa Cruz also conducted a study on the impact of climate change on Sierra’s Pinus contorta and P. jeffreyi seedlings. The study noted a significant decrease in the survival rate of the seedlings – attributed to the seedling’s shallow root system and lower capacity to store water (Alpert 48-49). In addition to decreased irrigation, the conifers also currently suffer from an increased infestation of fungi and insects, which gravitate towards warmer climates. Additionally, the combination of warmer temperature and more dried dead plant species, makes the environment more susceptible to fires, threatening the release of CO2 previously stored in the trunks of the trees. This release of CO2 will create a positive feedback to the global climate dilemma, sadly leading scientists and conservationist back to where they started.
About the authors: Stephen Holle and Birka Burnison are working towards their bachelor’s degrees in Environmental Studies in the USC Dana and David Dornsife College of Letters, Arts and Sciences.