Ice core data - Ice Ages and Interglacials: Measurements, Interpretation, and Models - page 162

Figure 4.23. Variation of temperatures and CO 2 since the LGM. Tropical Pacific SST changed
from about 26 to about 30 C over this period. South Pacific (45 S off the Chile coast) SST
changed from about 9 to about 16 C over this period. Deep-Pacific temperature rose by about
2 C over the short interval shown by the gray area near 18 kybp (Stott et al., 2007). Note that
the insolation curves are not those of Stott et al. and widely differ from them.

orbitally driven insolation changes in the Southern Hemisphere,
combined with a rise in atmospheric pCO 2 , were sucient to jump start the
deglacial warming around Antarctica without direct Northern Hemispheric
triggers. Analyses of sensitivity experiments forced with only one external forcing
component (greenhouse gases, ice-sheet forcing, or orbital forcing) demonstrate
that austral spring insolation changes triggered an early retreat of Southern
Ocean sea ice starting around 19-18 ka bp . The associated sea ice-albedo feed-
back and the subsequent increase of atmospheric CO 2 concentrations helped to
further accelerate the deglacial warming in the Southern Hemisphere.''

'' ...

However, there are some aspects of this analysis that seem strange to this
writer. A key element in the analysis is the timing of the putative rise in solar
insolation that is claimed to have triggered the retreat of sea ice and released CO 2
from the southern ocean. Timmermann et al. (2009) refer to two estimates of solar
insolation: ''Averaged austral spring insolation at 63 S using a fixed-length season