Two-phase change in CO 2, Antarctic temperature and global climate during Termination II

摘要

The end of the Last Glacial Maximum (Termination I), roughly 20 thousand years ago (ka), was marked by cooling in the Northern Hemisphere, a weakening of the Asian monsoon, a rise in atmospheric CO 2 concentrations and warming over Antarctica. The sequence of events associated with the previous glacial-interglacial transition (Termination II), roughly 136 ka, is less well constrained. Here we present high-resolution records of atmospheric CO 2 concentrations and isotopic composition of N 2 - an atmospheric temperature proxy - from air bubbles in the EPICA Dome C ice core that span Termination II. We find that atmospheric CO 2 concentrations and Antarctic temperature started increasing in phase around 136 ka, but in a second phase of Termination II, from 130.5 to 129 ka, the rise in atmospheric CO 2 concentrations lagged that of Antarctic temperature unequivocally. We suggest that during this second phase, the intensification of the low-latitude hydrological cycle resulted in the development of a CO 2 sink, which counteracted the CO 2 outgassing from the Southern Hemisphere oceans over this period.