CONTROL OF THE GLACIAL CARBON BUDGET BY TOPOGRAPHICALLY INDUCED MIXING
A stronger biological pump is thought to be the primary driver behind the oceanic uptake of atmospheric CO2 during glaciations. The conundrum is that a stronger biological pump requires less production of southern origin deep water whilst observations indicate a glacial deep ocean filled with more southern origin water than today. Here we demonstrate, using a theoretical box model, that the inverse relationship between volume and production rate of this water mass can be explained by invoking mixing rates in the deep ocean that are proportional to topographic outcropping area. Furthermore, we show that the resulting profile, of a near-linear decrease in mixing intensity away from the bottom, generates a positive feedback on oceanic CO2 uptake that can initiate a glacial cycle. The results point to the importance of using topography-dependent mixing when studying the large scale ocean circulation, especially in the paleo-intercomparison models (versions PMIP1.5 and PMIP2) that have failed to produce the weaker and more voluminous bottom water of the Last Glacial Maximum.
De Boer, A. M., Stockholm University, Sweden, email@example.com
Hogg, A. M., Australian National University, Australia, firstname.lastname@example.org
Location: 316 B
Presentation is given by student: No