Currently, 20% of species are at some threat of extinction. The number is increasing rapidly enough to suggest that by 2100 50% of species will be threatened with extinction. Humans are a species, too, a fact some people forget. Much of the threat to the other species is the growth in ours. For years we’ve been using up more than a planet’s worth of resources every year. It has been a long time since we’ve been living sustainably. Pollution and population control are our greatest tools, unless lifestyle changes and technological advancements enable yet another revolution.