Extinction is the termination of any lineage of organisms, from subspecies to species and higher taxonomic categories, from genera to phyla. Extinction can be local, in which one or more populations of a species or other unit vanish with others surviving elsewhere (also known as exterpation), or extinction can be total (global), in which all populations vanish.
Species extinction is a natural part of the evolutionary process. Due to human activities, however, species and ecosystems are more threatened today than ever before in recorded history. The losses are taking place in tropical forests -- where 50 - 90 per cent of identified species live -- as well as in rivers and lakes, deserts and temperate forests, and on mountains and islands. The most recent estimates predict that, at current rates of deforestation, some two to eight per cent of the Earth's species will disappear over the next 25 years. While these extinctions are an environmental tragedy, they also have profound implications for economic and social development. At least 40 per cent of the world's economy and 80 per cent of the needs of the poor are derived from biological resources. In addition, the richer the diversity of life, the greater the opportunity for medical discoveries, economic development, and adaptive responses to such new challenges as climate change. The variety of life is our insurance policy. Our own lives and livelihood depend on it.
In 2001, paleontologists reported that evolution does not accelerate quickly in response to rapid bursts of extinction, and that the Earth needs, on average, about 10 million years to recover from global extinctions, whether they involve the loss of most life on Earth or wipe out far fewer species. This is much longer than previously believed. One possible explanation for why diversification takes so long to speed up after an extinction is that extinction eliminates not merely species or groups of species, but removes ecological niches: the roles which organisms play within ecosystems. Recovery becomes more complicated because specialized roles, such as parasites that live on just one species, or animals that consume just one kind of food, do not evolve until their hosts are already well established.
The Convention on the Conservation of European Wildlife and Natural Habitats (Bern Convention, 1979) came into force in 1982. Initiated and developed by the Council of Europe the principal aim of the Convention is to protect flora and fauna and their habitats, and to promote international co-operation amongst the contracting parties in their conservation efforts, with particular emphasis on the protection of endangered and vulnerable species and their habitats, particularly migratory species. The Convention includes four annexes, listing threatened species.
Today human activities are driving species extinction at a rate of several species per hour -- thousands of times as fast as the rate of evolution of new species. This is akin to popping the rivets out of the airplane your children must fly in.
Extinction is not like knocking chess pieces off a chessboard, with the empty squares ready for you to plunk down new pieces. Extinction is more like knocking down a house of cards. You only have places to put new cards as you rebuild the structure of the house.