Forests are also a source of many medicines that we manufacture today, and there is no telling how many cures are being destroyed every day. Humans are trading biodiversity, food and medicinal sources, nutrient recycling, climate regulation, and watershed management for cropland, pasture, fuel, and urban development. Half of the planet's tropical forests have been destroyed or degraded. One production run of the Sunday New York Times requires product from 75,000 trees. Water Quality and Supply Intensive farming practices and deforestation cause siltation of streams and rivers.
Urbanization creates industrial and residential run-off, contaminating water supplies.
Between water pollution, rising affluence from socioeconomic development and a rapidly growing population, an insufficient supply of clean water threatens many regions. One billion people will be living in countries facing absolute water scarcity by 2025. No matter how humans interact with their environment, there is a clear correlation between population and species loss. The more people, the less wildlife. The population will be increasingly more urban in the 21 st century.