Carbon Cycle: 1985 Glacial to Interglacial Changes in the Operation of the Global Carbon Cycle

The hottest topic for those interested in the earth's carbon cycles is the change in atmospheric CO 2 content between glacial and interglacial time. What caused it? What is its role in glacial cycles? We evaluate here the hypotheses that have been put forward to explain the CO 2 change with evidence from deep sea sediments. We conclude that all the hypotheses have serious drawbacks and that much effort will have to be expended in gathering more data from ice cores and ocean sediments before we will be pointed toward the correct scenario. Also, thoughtful modeling aimed at depicting the ties between pCO 2 , O 2 , 13 C/ 12 C, 14 C/ 12 C, and nutrient constituents in the sea for various modes of circulation will have to be done before the evidence from ocean cores can be properly interpreted.