Hobbies And Interests
Rainfall Patterns
Rainfall depends on climatic processes outside deserts. For example, the Southern Oscillation, a global weather cycle associated with the El Nino and La Nina cycles, modulates year-to-year rainfall pattern variations. El Nino develops when warm water in the eastern equatorial Pacific Ocean decreases the upwelling of cold water along the coastlines of North and South America. The water surface heats up, resulting in increased rainfall along the coast in the winter. La Nina, a westward flow of surface currents that forces the upwelling of cold waters along the coasts, bringing drought to coastal deserts, follows El Nino. These climatic variations lead to alternating cycles of abundant and scarce resources.
Global Warming
According to a report issued by the United Nations Environment Programme, desert temperatures increased an average of 0.2 to 0.8°C between 1976 and 2000, much higher than the average global temperature increase of 0.45ºC. This is attributed to an increase of atmospheric greenhouse gases. The combined effect of reduced precipitation and more severe and protracted droughts will reduce soil moisture, reducing vegetative cover. Desert biodiversity will also be impacted. Increasing soil aridity will lead to the loss of grasses in favor of shrubs, creating a new ecosystem with "islands" of fertility under shrubs and nutrient-poor soils in barren areas.
Desertification
Desertification, or the degradation of formerly productive land, is complex, involving multiple causes and proceeding at different rates. While drought often triggers desertification, human activities are the leading cause. Increased population and overgrazing has accelerated desertification, leading to the loss of soil and vegetation cover and increased soil aridity. In the last 25 years, satellites have begun monitoring the impact of people and animals on the planet. Landsat images are improving our understanding of desertification.
Degradation
According to the Global Assessment of Human-Induced Soil Degradation, 20 percent of the world's deserts are affected by land degradation. The major causes of land degradation are overgrazing, wood collection, deforestation and non-sustainable agricultural practices. Apart from grazing and wood collection, these practices are restricted to the deserts' marginal edges, areas of the highest productivity. Overgrazing is the leading cause of land degradation. Wood collection and deforestation leads to soil erosion and changes in vegetation. Agricultural irrigation causes soil salinization and pollution.