I believe that the issue of world population and human impact on the
environment are relevant to this list.  The agricultural revolution created
a mechanism for rapid human overpopulation of the planet that we (a few of
us anyway) is slowly beginning to realize.

I would also like to say that I do not really agree with many of the
statements made in the "World's Scientists Warning to Humanity".
Particularly that improved living conditions and family planning will
stabilize the human population.  Dan Quinn has addressed the problems with
the "World's Scientists Warning to Humanity" at
http://www.ishmael.org/Education/Writings/kentstate.shtml.

Brad