Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

[Phys-L] Re: positive feedback loops (was global warming)



Hi all-
Well, I'm not sure of David's position, but I gather that some of
the strong opinions on this net are simply uninformed as to the presently
available evidence.
The most recent Antarctic ice core was reported in <Nature> for
June 10, 2004, and provides us with a 740 kyr record of climate and
atmospheric constituents. There are other measurements available of
the rise in atmospheric greenhouse gases since the start of the industrial
age. The connection between greenhouse gas composition and global warming
is borne out by the ice core evidence and does not involve such exotic
chemistry as to leave much room for doubt.
I suggest that, as physicists, we should be dealing with the
expeerimental evidence and reasonable inferences that can be drawn from
that evidence. Let's not fit ourselves into Landau's characterization (no
longer applicable, I think) of astrophysicists as being "often in error,
but never in doubt."
Regards,
Jack




On Fri, 17 Dec 2004, David T. Marx wrote:

The answer is that no one knows. The models that do include feedback make it a positive one and
thus get the scariest results, as you suggest. The chemistry of epoxy resin is much easier to
understand than the complex system that is the Earth's climate, however.

This morning, while walking through a nearby supermarket, I happened upon Michael Crichton's book
"State of Fear" that started this thread. The points he makes in his personal epilogue are right
on target. He and I are very much in agreement on the present situation and future of global
warming. There is no axe to grind, just an honest assessment of the science of climate change.

Take care,
David Marx

As one who has witnessed firsthand a rather striking
thermal positive feedback loop (by accidentally adding
way too much hardener to epoxy resin), I wonder
whether any of the models which relate atmospheric
temperature increase to human activity postulate this
sort of behavior. If there is a strong possibility
that such a feedback situation could/does exist, then
it seems very dangerous indeed to wait for solid
proof. Once the temperature of the resin mix starts
its rapid rise, smoke very quickly follows.

OTOH, if most atmospheric scientists & climatologists
believe that the feedback loop(s) are or will be
negative (or neutral) in nature, then we can well
afford to wait.

John Barrere University HS Fresno, CA




--
"Trust me. I have a lot of experience at this."
General Custer's unremembered message to his men,
just before leading them into the Little Big Horn Valley