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Re: Help my foggy memory please!
> The possibly overblown claim was that we have (in the
> recent past, I said since the Industrial Revolution) had
> killed off and were still killing off about the same number
> of species (I meant in percentage terms, I guess) as when
> the dinosaurs died out; in other words, we are artificially
> creating one of the great biological extinction events that
> some think happen every 26 million years ago.
> So, exactly what is the scoop? Have we already done so?
> Are we going to do so in a mere couple of years?
At least so far, the total number of extinctions just
qualifies as a *minor* extinction event - *even* if you
count all of the Late Pleistocene extinctions.
Now, it *is* true that if we continue this rate of extinction
for a great many more years we will have reached a level of
extinction matching the 5 biggies (of which the dinosaur extinction
was the last).
> I also have read/heard claims that something like half of
> the land species exist in the Amazon basin and the claim is
> we'll wipe most of it out in a couple more decades of slash
> and burn agriculture. Is the 50% number (or something very
> like it) true? Have we already wiped out a large number of
> species there?
Probably and yes.
That is, the number of species is *vastly* higher in a given
area of tropical rain forest than in any other habitat. By
extrapolating from known censuses, estimates of the total
diversity in the tropics all cluster around 50% or *higher*.
> Can anyone cite some sources that either confirm it or
> semi-confirm it?
Almost any good *scholarly* work on either biogeography
or tropical rain forests will do. Try a *university*
library near you for the best references.
The peace of God be with you.