The Worthington Effect and the origin of the Younger Dryas

wAn increase in CO(2) content of the atmosphere during deglaciation is explained by buildup of shelf carbonate with concomitant release of "excess CO(2)" to the surrounding upper ocean, from whence some of it enters the atmosphere. Mixing with deep water removes excess CO(2) to the abyss where it is used up in dissolving foraminifera and coccoliths. The two master variables of the model are the rate of accumulation of shelf carbonate and the time lag postulated for downward mixing of the excess CO(2) into deep waters. This lag is a function of the "Worthington Effect," that is, the slowdown of vertical mixing through the addition of meltwater. If we postulate a lag of 1000 years or more, then the atmospheric pCO(3) goes through an overshoot phase, which is followed by a rebound to low values. We suggest that the rebound is real and that it coincides with the Younger Dryas, a period of major cooling between 11,000 and 10,000 years ago. If this is accepted, then the mixing lag is near 2000 years.