There are three levels of biodiversity: genetic diversity which refers to genetic variation within and between species; species diversity which refers to the variety of species and individuals within each species; and ecosystem diversity which refers to the variety of habitats and ecological processes. Biodiversity loss is caused by habitat destruction, introduced species, overexploitation, pollution, climatic change, and industrial agriculture/forestry. Decreased natural environments can impact inspiration/recreation opportunities, education, tourism/the economy, endangered species, greenhouse gas emissions, air/water/soil quality, food shortages, and indigenous peoples who rely on the environment.