Desertification is defined as the process by which human practices cause the land to degrade in quality in arid, semi-arid, and dry sub-humid regions. Arid, semi-arid, and dry sub-humid regions are climate regions characterized by a lack of water, with arid being the most dry and dry sub-humid the least dry out of the three The lack of moisture in these areas can lead to poor development of plant and animal life. Desertification also presents the key concept of land degradation, which describes any process that adversely affects the value of land, reduces the productive capabilities of the land, or that threatens the biodiversity and ecology of the environment threatened by degradation. These two phenomena go hand-in-hand, as desertification is often a symptom of heightened land degradation. Human activities like over-farming, failing to practice crop rotation and overgrazing cause the nutrient content of soil in dryland ecosystems, which are ecosystems characterized by a lack of moisture,to degrade, which in turn makes the soil loose, dry, and therefore infertile and un-farmable. Desertification is not a new phenomenon. It has been around for as long as humanity has adopted an agrarian lifestyle. By looking back at cases of desertification in ancient times, it becomes more clear as to what the most basic contributing factors to desertification and soil depletion are, and how they can be remedied or worsened over time. Looking at modern cases allows for the examination of what approaches are most effective, and what measures will have to be taken in the future to ensure the security of millions of people currently suffering from the effects of desertification worldwide. Much of the confusion about the nature of this phenomenon stems from the fact that land degradation and expansion of deserts does occur naturally, but these events are fundamentally different from desertification. The great deserts of the world were formed by natural processes over long periods of time; they frequently grow and shrink independent of human activities, and are naturally prevented from expanding far beyond their historic boundaries by dense borders of vegetation.The main difference between this natural fluctuation in the size of large deserts and the expansion of deserts brought about by desertification is that human activities like clearing vegetation, overgrazing, and a host of others have both made it easier for existing desert areas to expand and have expedited the transitional periods of expansion, which refer to the amount of time it takes for existing deserts to overtake their surrounding lands11. This unnatural expansion of deserts then puts transition zones- areas where desert transitions into “Arable Land (% of Land Area).” The World Bank. Accessed May 19, 2017.- particularly at risk. Essentially, desertification is not attributed to the expansion of natural deserts; it encompasses more-so the idea that the increased presence of human activity is responsible for depleting soil to the point that the presence of deserts and desert-like conditions is amplified in places that were previously fertile. Many of the most prevalent causes of desertification have occurred for years, but combining them with our more modern problems like climate change make them even more detrimental to ecosystems and livelihoods. Over-farming is the process by which crops are planted continuously on the same plot of land without replenishing the nutrients of the soil or diversifying the crop. As populations continue to grow, more crops are needed to for sustenance, which results in over-farming and subsequently dry, degraded soil and erosion. As over-farming causes more land to become degraded and un-farmable, farmers are forced to clear more land for farming. This presents several problems: when vegetation is cleared, the roots that previously held soil in place are gone, allowing soil to be more easily eroded, and as farmland expands, the wildlife previously living in these areas becomes displaced, causing huge threats to biodiversity in desertified regions. Over-farming becomes even worse when combined with the use of poor farming techniques. For example, failing to utilize crop rotation depletes soil without ever replenishing nutrients. Crop rotation is the process by which one type of crop is planted on a patch of farmland, then a different type of crop is planted in the following season. This ensures that the soil of farmland is not depleted of the same set of nutrients with each harvest. Failure to practice such techniques makes the depletion of soil occur much more quickly Overgrazing is also a common contributor to desertification. The root systems of plants are important for keeping soil anchored and preventing erosion. When cattle are allowed to graze extensively, they eat the various sources of vegetation that holds the soil in place. When this vegetation is removed, it becomes easier for soil to be eroded by wind or water, thus resulting in a depletion of nutrient-rich soilless nutrientrich soil left over. Cattle grazing also results in the compression of depleted soil. As the animals graze, they pack down soil with their hooves. In areas where the soil has been depleted, this creates dense stretches of exhausted soil, which is harder to rehabilitate. These problems all contribute to the onset of desertification, and when they are allowed to continue, desertification soon sets in and spreads. Desertification is not an isolated issue. Drylands represent 40% of Earth’s landmass, and these regions can be found on every continent except Antarctica While desertification is a major problem itself, it is also fundamentally linked to other pressing issues like climate change, population displacement, and water scarcity.