poly: Global Warming

Science News has a two-page article about the spread of C4
plants versus C3 plants. (The two different systems plants
have for soaking up CO2 from the air.) If we believe the
article, C4 plants are favored when atmospheric CO2 falls
below 500ppm, which first happened about 12Myr ago.
Current level is about 350ppm, up from pre-industrial 280(?).

My interpretation: The evolution of humans is strong support
for the Gaia hypothesis. The planet realized it was headed
for disaster, with plants using up all the CO2 in the air and
sequestering it underground in peat bogs, coal seams,
petroleum, and carbonate rock from sea shells. It evolved
a temporary fix (C4 plants) which can cope with a thinner
food source, but disaster was clearly imminent: in a few
million more years, all the CO2 would be gone! As an
emergency response, humans were evolved to recycle the carbon
back into the biosphere.

:-)

Rich Schroeppel rcs@cs.arizona.edu
Received on Mon Jan 12 15:12:26 1998