Desertification

Abstract: In this millennium, global drylands face a myriad of problems that present tough research, management, and policy challenges Recent advances in dryland development, however, together with the integrative approaches of global change and sustainability science, suggest that concerns about land degradation, poverty, safeguarding biodiversity, and protecting the culture of 25 billion people can be confronted with renewed optimism We review recent lessons about the functioning of dryland ecosystems and the livelihood systems of their human residents and introduce a new synthetic framework, the Drylands Development Paradigm (DDP) The DDP, supported by a growing and well-documented set of tools for policy and management action, helps navigate the inherent complexity of desertification and dryland development, identifying and synthesizing those factors important to research, management, and policy communities

Abstract: Studies of ecosystem processes on the Jornada Experimental Range in southern New Mexico suggest that longterm grazing of semiarid grasslands leads to an increase in the spatial and temporal heterogeneity of water, nitrogen, and other soil resources. Heterogeneity of soil resources promotes invasion by desert shrubs, which leads to a further localization of soil resources under shrub canopies. In the barren area between shrubs, soil fertility is lost by erosion and gaseous emissions. This positive feedback leads to the desertification of formerly productive land in southern New Mexico and in other regions, such as the Sahel. Future desertification is likely to be exacerbated by global climate warming and to cause significant changes in global biogeochemical cycles.

Abstract: Climate change is causing drylands to expand and this work shows that they will cover half of the land surface by 2100 under a moderate emissions scenario. Drylands are home to more than 38% of the total global population and are one of the most sensitive areas to climate change and human activities1,2. Projecting the areal change in drylands is essential for taking early action to prevent the aggravation of global desertification3,4. However, dryland expansion has been underestimated in the Fifth Coupled Model Intercomparison Project (CMIP5) simulations5 considering the past 58 years (1948–2005). Here, using historical data to bias-correct CMIP5 projections, we show an increase in dryland expansion rate resulting in the drylands covering half of the global land surface by the end of this century. Dryland area, projected under representative concentration pathways (RCPs) RCP8.5 and RCP4.5, will increase by 23% and 11%, respectively, relative to 1961–1990 baseline, equalling 56% and 50%, respectively, of total land surface. Such an expansion of drylands would lead to reduced carbon sequestration and enhanced regional warming6,7, resulting in warming trends over the present drylands that are double those over humid regions. The increasing aridity, enhanced warming and rapidly growing human population will exacerbate the risk of land degradation and desertification in the near future in the drylands of developing countries, where 78% of dryland expansion and 50% of the population growth will occur under RCP8.5.

Abstract: This text aims to summarize the state of scientific knowledge on the drylands of the globe. It explores the current stage of understanding of desertification as well as its extent and possible solutions. The book argues that desertification is one of the world's most pressing environmental problems and that it is a global issue which is accelerating. This edition has been revised and expanded to include updated computer images of desertification, as well as fuller descriptions and explanations of the issues concerned. Using detailed data of the physical and chemical status of soil degradation provided by the Global Assessment of Soil Degradation, the book is fully referenced and covers topics including: desertification and global warming; monitoring on the ground and by remote sensing; vegetation and degradation; local action; cultural factors; financial issues; land reclaimations; the political economy and desertification; and desertification and refugees.