On Apr 12, 5:48 pm, James Annan <[EMAIL PROTECTED]> wrote:
> ...
> Not that it matters for the
> general point. CO2 can't reasonably account for all the temperature
> change but must have contributed a significant proportion. As such, it's
> hard to see how the climate can be insensitive to radiative forcing changes.
I agree.
> And there are
> vegetation (albedo) changes too.
Certainly so. For the Amazon basin, the best data is from
40--30 kya. At that time, and there is no reason to
suppose it was any different right at LGM, the Amazon basin
was almost entirely savannah. Near the current mouth of
the Amazon River there were extensive, active, aeolean sand
dunes. Precipitation in the northern part of the Amazon
basin consisted of gigantic flash floods, moving boulders
up to at least one meter in diameter. The tropical rain
forest retreated to only the Peruvian foothills (and
possibly further north, outside the Amazon basin --- I have
seen no data regarding the Orinoco, etc., at that time
depth.)
Currently the ITCZ is about 14 degrees north latitude in the
vicinity of South America, far enough north that the southern
portion of the Amazon basin is reverting to savannah once
again. I can only surmise that the ITCZ was about that far
north during these early times.
On the other hand, it could not have been much further north
than that based on the continuation of the tropical rain
forests in northern Panama, Nicaragua, Costa Rica, etc.
Maybe the Hadley cells were smaller then?
> But I still see no reason to single out
> CO2 as a credible candidate for having had no effect whatsoever.
Who is doing that?
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