Gareth wrote:
> On Apr 12, 5:00�am, Eric Swanson <[EMAIL PROTECTED]> wrote:
>
> > Roy Spencer's presentation was given on the last session at the very
> > end of the list and there's no mention of a proceedings of his
> > presentation. �Maybe there's something in the audio section, since it
> > would appear that Spencer is just talking?? � I think Spencer's claims
> > must also pass the same basic question as Lindzen's, which is, how
> > could there have been Ice Ages if there is a strong negative feedback
> > due to tropical clouds?
> >
> Talk me through the ice age connection. Do you mean that we could not
> warm out of an ice age if there was a strong negative feedback in the
> tropics?
As I recall (and I admit to being fuzzy about it) the Earth was some 5
or 6 C colder and the Tropics also cooled during the last Ice Age at
LGM. While lower CO2 levels might have caused that, wouldn't the IR
Iris and cloud feedback have prevented the cooling, just as they are
supposed to be preventing warming from increased greenhouse gases? I
would guess that the proposed feedback might also apply at mid
latitudes over the oceans, but I haven't studied the paper or
Spencer's slides and am otherwise not up on the question. Maybe
someone else could comment.
I did notice from the 2007 GRL paper that Spencer looked at zones from
20S to 20N, an area which would be centered on the Equator. But, the
thermal Equator, the ITCZ, is not so positioned. Whether that would
have any impact on the analysis, I could not say.
E. S.
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