When we approach any discussion of the environment, we MUST remember that what
we are observing is only a minute moment in a very long history of the planet Earth.
Check out the web site below. Also, see the place below where I have marked today on a
time line of history. The reality is that there have been anywhere from 6 (for sure) to 23
mass extinctions of species on this planet, None of them were caused by humans! (Chew
on that for a minute).
http://www.bbc.co.uk/education/darwin/exfiles/massintro.htm