Simple fact is, the extinction rate is 100 times, headed for 1000 times normal. * * * *
Cite your sources. Links. Not that you have a major credibility problem or anything.
Let's get the baseline. What is normal in extinctions? How the **** do we even "know?"
Have the numbers been fucked-with like the data for global hoaxing -- err -- global warming?
Evolution: Library: The Current Mass Extinction
The Current Mass Extinction:
Is the biosphere today on the verge of anything like the mass extinctions of the geological past? Could some equivalent of meteorite impacts or dramatic climate change be underway, as humankind's rapid destruction of natural habitats forces animals and plants out of existence?
Increasingly, researchers are doing the numbers, and saying, yes, if present trends continue, a mass extinction is very likely underway. The evidence is pieced together from details drawn from all over the world, but it adds up to a disturbing picture. This time, unlike the past, it's not a chance asteroid collision, nor a chain of climatic circumstances alone that's at fault. Instead, it is chiefly the activities of an ever-growing human population, in concert with long-term environmental change.
The background level of extinction known from the fossil record is about one species per million species per year, or between 10 and 100 species per year (counting all organisms such as insects, bacteria, and fungi, not just the large vertebrates we are most familiar with). In contrast, estimates based on the rate at which the area of tropical forests is being reduced, and their large numbers of specialized species, are that we may now be losing 27,000 species per year to extinction from those habitats alone.
The typical rate of extinction differs for different groups of organisms. Mammals, for instance, have an average species "lifespan" from origination to extinction of about 1 million years, although some species persist for as long as 10 million years. There are about 5,000 known mammalian species alive at present. Given the average species lifespan for mammals, the background extinction rate for this group would be approximately one species lost every 200 years. Of course, this is an average rate -- the actual pattern of mammalian extinctions is likely to be somewhat uneven. Some centuries might see more than one mammalian extinction, and conversely, sometimes several centuries might pass without the loss of any mammal species. Yet the past 400 years have seen 89 mammalian extinctions, almost 45 times the predicted rate, and another 169 mammal species are listed as critically endangered.
Therein lies the concern biologists have for many of today's species. While the number of actual documented extinctions may not seem that high, they know that many more species are "living dead" -- populations so critically small that they have little hope of survival. Other species are among the living dead because of their interrelationships -- for example, the loss of a pollinator can doom the plant it pollinates, and a prey species can take its predator with it into extinction. By some estimates, as much as 30 percent of the world's animals and plants could be on a path to extinction within 100 years. These losses are likely to be unevenly distributed, as some geographic areas and some groups of organisms are more vulnerable to extinction than others. Tropical rainforest species are at especially high risk, as are top carnivores, species with small geographic ranges, and marine reef species.
