Constraint of the CO_2 rise by new atmospheric carbon isotopic measurements during the last deglaciation

摘要

The causes of the ～80 ppmv increase of atmospheric carbon dioxide (CO_2) during the last glacial.interglacial climatic transition remain debated. We analyzed the parallel evolution of CO_2 and its stable carbon isotopic ratio (δ~(13)CO_2) in the European Project for Ice Coring in Antarctica (EPICA) Dome C ice core to bring additional constraints. Agreeing well but largely improving the Taylor Dome ice core record of lower resolution our δ~(13)CO_2 record is characterized by a W shape, with two negative δ~(13)CO_2 excursions of 0.5% during Heinrich 1 and Younger Dryas events, bracketing a positive δ~(13)CO_2 peak during the B?lling/ Aller?d warm period. The comparison with marine records and the outputs of two C cycle box models suggest that changes in Southern Ocean ventilation drove most of the CO_2 increase, with additional contributions from marine productivity changes on the initial CO_2 rise and δ13CO_2 decline and from rapid vegetation buildup during the CO_2 plateau of the B?lling/Aller?d.