Ok, I admit to throwing in the deforestation stuff knowing it was off-track... but WHOIS quoted AGU, and that opens up the discussion to all the various avenues. After all, you put up the links...
I intentionally brought up the GCM problems, and they ARE central to the issue.
The ocean current that you talked about is one of Richard Alley's major interests, and look at what the Committee on Abrupt Climate Change, chaired by him, has to say about them:
"At present, the models used to assess
climate and its impacts cannot simulate the size,
speed, and extent of past abrupt changes, let alone
predict future abrupt changes. Efforts are needed to
improve how the mechanisms driving abrupt climate
change are represented in these models and to more
rigorously test models against the climate record."
Again, I have to question, just what triggered these other abrupt changes, if it wasn't us???? The thermohaline stops, it starts.....and stops, and starts...
Sorry sports fans, but that puts us well into the realm of normal variability.
"......tree rings show the frequency of
droughts, sediments reveal the number and type of
organisms present, and gas bubbles trapped in ice cores
indicate past atmospheric conditions. With such
techniques, researchers have discovered repeated
instances of large and abrupt climate changes over the
last 100,000 years during the slide into and climb out of
the most recent ice age—local warmings as great as 28°F
(16°C) occurred repeatedly, sometimes in the mere span
of a decade."
http://dels.nas.edu/dels/rpt_briefs/...ange_final.pdf