Glacial terminations as southern warmings without northern control

• Published in: Nature Geoscience
• Main Authors: Wolff, E. W., Fischer, H., Röthlisberger, R.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Publishing Group 2009
• Subjects: 530 Physics; Antarctic; Antarc*; Antarctica
• Online Access: https://boris.unibe.ch/37517/1/ngeo442.pdf; https://boris.unibe.ch/37517/

The change from a glacial to an interglacial climate is paced by variations in Earth’s orbit1. However, the detailed sequence of events that leads to a glacial termination remains controversial. It is particularly unclear whether the northern2,3 or southern4,5,6 hemisphere leads the termination. Here we present a hypothesis for the beginning and continuation of glacial terminations, which relies on the observation that the initial stages of terminations are indistinguishable from the warming stage of events in Antarctica known as Antarctic Isotopic Maxima7, which occur frequently during glacial periods. Such warmings in Antarctica generally begin to reverse with the onset of a warm Dansgaard–Oeschger event in the northern hemisphere7,8. However, in the early stages of a termination, Antarctic warming is not followed by any abrupt warming in the north. We propose that the lack of an Antarctic climate reversal enables southern warming and the associated atmospheric carbon dioxide rise to reach a point at which full deglaciation becomes inevitable. In our view, glacial terminations, in common with other warmings that do not lead to termination, are led from the southern hemisphere, but only specific conditions in the northern hemisphere enable the climate state to complete its shift to interglacial conditions.