Abstract

The effects of ocean circulation on steady-state atmospheric CO2 concentration in ocean models pertaining to glacial climates are reviewed in this chapter. In this context, it appears that ocean circulation changes could provoke four basic effects: (1) Circulation-activated change in calcium carbonate (CaCO3) production can change the deep ocean CO3 = concentration and (2) the rain ratio of organic C to CaCO3 production; (3) change in thermohaline circulation or upper ocean mixing may alter the shape of the vertical gradient of dissolved CO3=; and (4) changing thermohaline circulation may interact with both biological production and air–sea exchange in high-latitude deep water formation areas to effect change in atmospheric CO2 through the solubility and biological pumps.

Introduction

The records of calcium carbonate (CaCO3), carbon isotopes, Cd/Ca ratio, and benthic forminiferal speciation indicate that the ocean circulation varies with climate change during the Pleistocene (Crowley, 1985; Mix and Fairbanks, 1985; Boyle and Keigwin, 1985; Duplessy et al., 1988).spheric C02 appears to decrease by approximately 90 ppm during ice ages as compared to relatively warm climates such as that of the Holocene (Barnola et al., 1987; Neftel et al., 1988). Various models of the ocean and atmosphere have been developed to simulate proposed mechanisms that might have produced the glacial-interglacial CO. change, and some of these models include changes in various circulation parameters (Knox and McElroy, 1984; Sarmiento and Toggweiler, 1984; Siegenthaler and Wenk, 1984; Broecker and Peng, 1981; Keir, 1988; Boyle, 1988; Heinze et al., 1991).