because the human population is growing so rapidly, we are crowding out other species. As people take up more space and use more resources, we destroy the habitats of other species. More species are going extinct because of habitats destruction today than ever before. global warming is s threat that is causing a change of climate for animals, such as the polar bear. the polar bear is a threatened species. this means that it will become endangered if something is not done to protect it. an endangered species is one whose numbers are so low that it is likely to become extinct.