The astronomical theory and data compared - Ice Ages and Interglacials: Measurements, Interpretation, and Models - page 300

Figure 10.15. Taylor Dome record of atmospheric CO 2 over the most recent glacial
termination and the INTCAL reconstruction of atmospheric d 14 C over the past 25,000 years
(Stott and Timmerman, 2011).

the relative abundance of 14 C in the atmosphere decreased remarkably (as
recorded in ice cores). The variability of the cosmic ray production of 14 C cannot
possibly account for such a large change. During the period after the LGM when
the CO 2 concentration in the atmosphere was steadily increasing, the 14 C propor-
tion steadily decreased (see Figure 10.15 ). Therefore, Stott and Timmerman (2011)
reasoned that there must have been a source of 14 C-depleted water in the upper
ocean and, as CO 2 was emitted from the ocean surface, it carried low levels of
14 C into the atmosphere.
As Stott and Timmerman (2011) pointed out:

''The record of surface ocean d 14 C change during the last glacial termination
provides an important constraint to any hypothesis that attempts to explain
glacial/interglacial atmospheric CO 2 variability via an ocean-only mechanism.
The rise in atmospheric CO 2 during the last deglaciation coincided with a long-
term decrease in atmospheric radiocarbon ( d 14 C). The atmospheric d 14 C change
during the last deglaciation implies either a change in production of 14 C in the
atmosphere or large redistribution of carbon between the surface ocean and a
14 C-depleted reservoir. Reconstructions of surface ocean d 14 C reveal several
shorter-term excursions during the past 30 kyr that were not associated with
cosmogenic isotope events, and thus, the excursions cannot be explained by
changes in the production rate of

14 C.''