Iran's high grasslands have been eroded for centuries by the encroachment of nomads who overgrazed their livestock. Desertification resulting from erosion, and deforestation of the high plateau pose additional dangers to Iran's environment. UN sources estimate that 1 to 1.5 million hectares per year become desert land. The basic law controlling the use of forests dates from 1943. In 1962, the forests and pastures in Iran were nationalized to check trespassing deforestation. In early 1983, blown-out oil wells in the Persian Gulf war zone between Iran and Iraq caused a huge oil slick that threatened ocean and shore life along the southwestern Iranian coast. Air and water pollution have become significant problems in Iran in the aftermath of the 1991 Persian Gulf War. The water in the Gulf is polluted with oil and black rain, and the burning of Kuwaiti oil wells caused significant air pollution as well. Iran also has the 19th highest level of industrial carbon emissions in the world, with a 1992 total of 235 million metric tons, a per capita level of 3.81 metric tons. Iran has 128.5 cubic kilometers of renewable water resources with 92% used for farming activity and 2% used for industrial purposes. Only 83% of the rural people have pure drinking water. Iran's cities produce about 6.2 million tons of solid waste per year. Iran's Department of Environment was established under the Environment Protection and Enhancement Act of 1974; no information is available on implementing legislation.
As of 2001, 20 of Iran's mammal species and 14 bird species are endangered. Endangered species in Iran include the Baluchistan bear, Asiatic cheetah, Persian fallow deer, Siberian white crane, hawksbill turtle, green turtle, Oxus cobra, Latifi's viper, dugong, and dolphins. The Syrian wild ass has become extinct.