The present report is the fourth in a series of reports published every five years on environmental trends in the region. The report looks at the prevailing environmental conditions in the terrestrial, aquatic and atmospheric systems and highlights the responses to environmental problems. It examines the relationship between environmental change and economic and social conditions. In addition, it reviews the national and regional responses to the problems of environment and sustainable development. It also presents key emerging issues in human ecosystems, which are described in terms of urban environment, wastes, poverty and food security. Finally, the report identifies key challenges and areas in which urgent action is needed, particularly in regard to regional and international collaboration efforts.