The Impact of Orbital Precession on Air‐Sea CO₂ Exchange in the Southern Ocean

Abstract

Orbital precession has been linked to glacial cycles and the atmospheric carbon dioxide (CO2) concentration, yet the direct impact of precession on the carbon cycle is not well understood. We analyze output from an Earth system model configured under different orbital parameters to isolate the impact of precession on air‐sea CO2 flux in the Southern Ocean—a component of the global carbon cycle that is thought to play a key role on past atmospheric CO2 variations. Here, we demonstrate that periods of high precession are coincident with anomalous CO2 outgassing from the Southern Ocean. Under high precession, we find a poleward shift in the southern westerly winds, enhanced Southern Ocean meridional overturning, and an increase in the surface ocean partial pressure of CO2 along the core of the Antarctic Circumpolar Current. These results suggest that orbital precession may have played an important role in driving changes in atmospheric CO2.

The Role of Ocean Mesoscale Variability in Air‐Sea CO2 Exchange: A Global Perspective

“…The model is forced by the Japanese 55‐year Reanalysis (JRA55) (Kobayashi et al., 2015) from 1958 to 2000. The air‐sea CO 2 flux in the model is calculated based on the bulk formula (Persch et al., 2023) with forced atmospheric conditions and simulated p CO 2 . A detailed description of the ocean configuration is given by Bryan and Bachman (2015); Guo, Bishop, et al.…”

Southern Ocean Biological Pump Role in Driving Holocene Atmospheric CO2: Reappraisal

“…The position of the Southern Westerly Winds (SWW) plays a key role in global climate variability owing to the link between latitudinal shifts in the SWW and Southern Ocean upwelling, which leads to CO 2 outgassing (Ai et al, 2020;Marshall & Speer, 2012;Sigman & Boyle, 2000). Modeling studies generally support the link between SWW intensity (Tschumi, et al, 2008) and/or position (Huiskamp et al, 2016;Persch et al, 2023), Southern Ocean ventilation, and atmospheric CO 2 concentration albeit with some disagreement about the sign of changes. They do, however, agree on the shared roles of the physical and biological pumps in determining atmospheric CO 2 concentrations.…”