|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|||||||
|
|
|
|
|
|
|
|
|
||
Summary
In summary, we live on a planet that, from space, looks blue. It has
water existing in all three phases. On closer inspection, we can see
that we have a green planet, with a rich diversity of biological
species. However, the habitable zone of this planet that supports
biological activity is a very thin shell around the surface of the
planet. The region of the earth in which humans can live without life
support systems is a thin spherical shell about 3 kilometers thick on a
planet of radius 6,370 km. If the earth was the size of a basketball,
this zone of human habitation would be about the thickness of a sheet of
paper. This is the only known zone in the universe where humans can exist
without life support systems. And now humans are performing a global experiment
-- a chemistry experiment -- on this habitable zone without knowing what the
consequences might be. As concerned citizens and future leaders of the
planet, we have two options: we can cover our eyes and pretend there is
no problem, or we can use the tools at our disposal to study this
problem -- to evaluate the evidence, to look at the scientific results,
and answer for ourselves what level of certainty we have about these
issues. And what are the consequences -- environmentally, socially, and
economically -- of acting or of failing to act in determining the nature
of our global chemistry experiment. What future do we leave to our
grandchildren?