Solubility happens quickly, so the CO2 should change quickly with ocean temperature changes. Why would the CO2 levels lag by such a long period of time? Is it because ocean temperatures lagged the atmospheric temperatures?
Not sure. Here again is the excerpt and link which I earlier posted:
"Carbon dioxide in the atmosphere [historically] is the product of oceanic respiration due to the well-known but under-appreciated solubility pump. Carbon dioxide rises out of warm ocean waters where it is added to the atmosphere. There it is mixed with residual and accidental CO2, and circulated, to be absorbed into the sink of the cold ocean waters. Next the thermohaline circulation carries the CO2-rich sea water deep into the ocean. A millennium later it appears at the surface in warm waters, saturated by lower pressure and higher temperature, to be exhausted back into the atmosphere. Throughout the past 420 millennia, comprising four interglacial periods, the Vostok record of atmospheric carbon dioxide concentration is imprinted with, and fully characterized by, the physics of the solubility of CO2 in water, along with the lag in the deep ocean circulation.
http://www.rocketscientistsjournal.com/2006/10/co2_acquittal.html