부산대학교 도서관

Atmospheric CO2 concentrations (pCO2) varied on millennial timescales in phase withAntarctic temperature during the last glacial period. A prevailing view has been that carbonrelease and uptake by the Southern Ocean dominated this millennial-scale variability inpCO2. Here, using Earth System Model experiments with an improved parameterization ofocean vertical mixing, we find a major role for terrestrial and oceanic carbon releases indriving the pCO2 trend. In our simulations, a change in northern hemisphere insolationweakens the Atlantic Meridional Overturning Circulation leading to increasing pCO2and Antarctic temperatures. The simulated rise in pCO2 is caused in equal partsby increased CO2 outgassing from the global ocean due to a reduced biologicalactivity and changed ventilation rates, and terrestrial carbon release as a response tosouthward migration of the Intertropical Convergence Zone. The simulated terrestrialrelease of carbon could explain stadial declines in organic carbon reservoirs observedin recent ice core δ13C measurements. Our results show that parallel variationsin Antarctic temperature and pCO2 do not necessitate that the Southern Oceandominates carbon exchange; instead changes in carbon flux from the global oceanand land carbon reservoirs can explain the observed pCO2 (and δ13C) changes. [ABSTRACT FROM AUTHOR]