Twenty to 30 percent of species are at greater risk of extinction due to climate change linked to global warming. Climate change has led to the disappearance of animals dependent upon micro-climates that have changed as a result of global warming, such as tree frogs in Central America. Climate change has also led to a change in larger ecosystems, endangering polar bear habitats due to the receding ice range in the north, which has given them less space to hunt and less food to eat.
Pollution from industry and human waste has led to the endangerment of many aquatic species. Industrial chemical discharges can make the water poisonous and lead to physical abnormalities for species living in these habitats. Leopard frogs in the United States, for example, have been affected by the release of chemical herbicide, resulting in some frogs developing both male and female sex organs and an inability to reproduce. Water pollution has destroyed fish and amphibian habitats in streams, lakes and rivers, resulting in endangerment.
Habitat destruction is the main source of species endangerment and has been caused by a number of human activities, especially at the beginning of the 20th century. Encroachment on natural habitats by farmers, loggers and other land developers has resulted in an enormous loss of habitat. This, in turn, has led to mass endangerment of species. Pollution of natural habitats and the change in climate, as a result of global warming, have also led to a change in habitat, to which many species are unable to adapt.
Wildlife trafficking has been devastating to many target species in their local habitats. The fur trade, reaching its peak in the period of the 1950s and 1960s resulted in the importation of 10 000 leopard, 15 000 jaguar, 3 000 cheetah and 200,000 ocelot furs into the United States before the import of furs was halted. The fur trade, during this period, contributed to the decline and endangerment of these species. The trade in ivory was also banned by signatory countries of the Convention on International Trade in Endangered Species in the 1990s; however, demand in China for ivory has led to an increase in poaching and the export of black market ivory to China in recent years. Cockatoos and apes have been captured, trafficked and sold as pets in foreign countries. Moreover, a demand for exotic meat and body parts for medicine in countries, such as China, has resulted in greater decline of species, particularly tigers.