Are atmospheric CO 2 content and pleistocene climate connected by wind speed over a polar mediterranean sea?

Abstract

Dust and sea-salt records in polar ice cores indicate that the climate has been windier during ice-ages, and therefore the rate of gas exchange between the atmosphere and ocean should be greater in glacial periods. Increased gas exchange between the atmosphere and poleward-advected, sinking cold water due to higher wind speeds could make the solubility pump more efficient, and this would decrease atmospheric CO 2. To illustrate how this might contribute to atmospheric CO 2 change over the last 150 kyr, the marine Na-concentration in the Vostok ice core is used as a logarithmc proxy for relative wind speed, from which gas piston velocities relative to the present are estimated. The effect of the cold water piston velocity on atmospheric CO 2 is then calculated according to an atmosphere-surface ocean box model. As a results, the solubility pump lowers atmospheric CO 2 about 50 ppm during oxygen isotope stages 2–4 and about 40 ppm during stage 5a-d. Unlike various nutrient rearranging mechanisms, the solubility pump produces little fractionation of carbon isotopes between the surface and deep ocean. Combining wind-induced solubility and nutrient-based effects, using Δδ 13C in deep-sea core V19–30 as a proxy of the latter, produces a record of atmospheric CO 2 which is similar to that observed in the Vostok ice core.