qThe large changes in atmospheric
CO2 over intervals of a few thousand years must involve rapid exchanges
(compared to the rate of exchange between the atmosphere and rock) among: the atmosphere,
vegetation and soil, surface and deep ocean.
qNot vegetation and
soil: because
vegetation reduced during glaciations.
qNot surface ocean: because surface ocean exchanges
CO2 quickly (in a few years) with the atmosphere.
qThe glacial carbon removed from
the atmosphere, from the vegetation, and from the surface ocean must have been stored in
the deep ocean.
qCarbon was exported to the deep
ocean by higher rates of photosynthesis and biological productivity.