Development, natural-resource use, and the environment have become so inextricably linked that they need to be jointly managed. The synergies have become so large that the very success of development is conditional on its impact on resource availability and environmental sustainability. Water use for irrigation in agriculture contributes to a global water shortage and deterioration of potable water quality. Deforestation, especially in tropical environments, leads to local changes in rainfall patterns and greenhouse gas emissions that contribute to global climate change, the flooding of lowlands and silting of dams and irrigation infrastructure, desertification of the use of cleared lands for agriculture, and loss of biodiversity. Air pollution originates principally in the burning of coal and petroleum for transport, heating, and industrial production.