Re: [asa] Re: global warming

It's true that CO2 and temperature have been higher in the geologic
past, though finding precise measures can be problematic. Nature just
had a study reporting that tree leaves from several climates yield a
similar 18O signal-biological effects make it not a true record of
environmental 18O. Organisms have a bad habit of using biochemistry
instead of easily characterized, simple reactions to make hard parts,
and this alters isotopic ratios and other features of interest. In
relatively simple reaction situations, there's a fairly direct
proportionality between the stable isotope ratios and the ambient
temperature. Throw life in the mix, and there can be problems.

The real problem is how fast the change is occurring. I don't know of
anything since the end-Paleocene (about 55 million years ago) that
might approach the modern rate of change in temperature and CO2.
Organisms have trouble keeping up or keeping in syc.

I'm inclined to agree with Glenn that running out of oil is the most
pressing issue, though of course conserving oil would probably also
cut back on CO2 emissions. Given several million years to recover, a
higher CO2 world would probably evolve some nice mollusk faunas on the
newly flooded and warm-water regions of the continental shelf, and it
could produce greater isolation between river systems (flooding
present-day connections that are near sea level), thus promoting new
species in freshwater as well. Of course, if humans continued to
modify things (or other variation happened) so that the organisms
didn't have time to catch up, then the recovery time would reset.

Does the east Texas ranch have any mollusks? I need to get DNA for a
few mussels from that area.

-- 
Dr. David Campbell
425 Scientific Collections
University of Alabama
"I think of my happy condition, surrounded by acres of clams"
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