Robert A. Rohde wrote:
> bill wrote:
>
> <snip>
>
> > http://www.scotese.com/climate.htm
> > This shows clearly a geological history of global temperature.
> > Note the plateau at 22 degrees C. These times included ANY time when
> > the atmospheric CO2 exceeded approximately 600 ppm, including millions
> > of years when it ixceeded 2000 ppm and further milions of years when it
> > exceeded 4000 ppm with no additional corresponding warming whatsoever.
> > What source to you use to imply that that is either innacurate or
> > irrelovent? If we are planning to expend the herculean efforts
> > involved in a 550 ppm stabilization (again, I am sceptical that 25%
> > current emissions would produce that) and 600 ppm is the response
> > ceiling, then what's the point??
>
> <snip>
>
> Scotese's climate plot is useful work, in its own way, but it is also
> one of the most poorly understood plots in the global warming debate.
> Scotese looks at climate zones, and most paricularly the presense or
> absence of continental ice sheets. If there is no ice at the poles he
> assigns a temperature of 22 C. If there are well developed ice sheets,
> he assigns a temperature of 12 C. Intermediate states get intermediate
> values, and a handful of exceptional events lead to extra wiggles. The
> idea that climate is stable at 22 C or 12 C is an assumption of the
> model, there is no specific evidence in Scotese's work to justify it.
> In fact, aside from deciding on a temperature to be representative of
> the unglaciated world, his work incorporates almost no direct
> temperature evidence at all, merely indirect evidence of the climate
> style.
>
> Scotese can't really tell you whether past warm periods were warmer
> than today, or whether past cold periods were colder. Also, quite
> obviously, he doesn't capture any rapid fluctuations in climate. You
> shouldn't use Scotese's work as evidence, either for or against, the
> stability of climate (or saturation of warming) under high CO2 levels.
Thank you.
I will look more closely into the O18 methodology for correlating
paleoclimate temperatures.
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups
Global Change ("globalchange") newsgroup. Global Change is a public, moderated
venue for discussion of science, technology, economics and policy dimensions of
global environmental change.
Posts will be admitted to the list if and only if any moderator finds the
submission to be constructive and/or interesting, on topic, and not
gratuitously rude.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to [EMAIL PROTECTED]
For more options, visit this group at
http://groups.google.com/group/globalchange
-~----------~----~----~----~------~----~------~--~---
