Severity of desertification on world stage   Desertification puts the health and well-being of more than 1.2 billion people in more than 100 countries at risk, according to the United Nations.   A spatial modelling tool has been developed in DesertWatch to simulate scenarios of desertification (named ScenDes). The tool generates possible scenarios for desertification monitoring, starting with a land use map at a certain time and simulating the land use evolution during the years. The simulation is typically carried out on periods of 10-20 years and allows to visualise possible land use degradation scenarios. These land uses can then be translated into desertification indicators.   The Land Degradation Index (LDI) exploits remote sensing images, in conjunction with climatic and physiographic parametres, for assessing the landscape status with respect to its natural resources potential. Homogeneous land systems are identified and their status is expressed in terms of number of standard deviations from the population mean. The final values are then converted into 3 broad classes that indicate overgrown, normal and undergrown vegetation. These results were obtained from ESA's DesertWatch project. Release date: 15 June 2007