From: Smigrodzki, Rafal (SmigrodzkiR@msx.upmc.edu)
Date: Mon Mar 25 2002 - 11:38:00 MST
Mike Lorrey [mailto:mlorrey@datamann.com]
Wrote:
However, this is not relevant to Spike's point. The point is
that
sequestration of carbon to the point that Ice House
conditions become
prevalent results in the Earth eventually losing most of its
atmosphere
as Mars did. We've already lost 98% of the atmosphere we
started with
3.5 billion yrs ago, most of which is tied up in limestone,
marble, etc
and will not be released by any tectonic processes.
#### Well, during heating in subduction zones the
carbonaceous rocks release large amounts of carbon dioxide, which is vented
during volcanic eruptions. In the past 2 billion years there was a dynamic
equilibrium maintained between processes of CO2 sequestration and release,
with large amounts bubbling up from deep in the mantle, or conversely, being
carried deep into it by convection flows. While, according to some theories,
such as the "snowball Earth", there were major fluctuations in CO2
concentration, there appears to be no long-term tendency towards "loss of
atmosphere". The 98% figure you mention might pertain to the initial change
brought about by biogenic processes at the onset of the archaic era, but
since then, as I said above, hardly anything changed.
And, BTW, independent of the above, I am for many reasons
very skeptical of any need for extensive and expensive measures for CO2
output reduction.
Rafal
This archive was generated by hypermail 2.1.5 : Sat Nov 02 2002 - 09:13:05 MST