It is estimated that half of the 10 million species of organisms on the planet live in the tropical rainforests. Deforestation of the rainforest causes the extinction of as many as 50,000 species per year. Clearing tropical rainforests causes the extinction of many species because
1) pollution caused by humans increases the greenhouse effect.
2) destruction of a rainforest contributes to the depletion of the ozone layer.
3) animals and plants are exposed to increased levels of carbon dioxide.
4) many unique habitats and ecosystems are being completely destroyed.
