Editor's Summary

26 February 2009

The north–south climate seesaw


Theoretical models and observational data have long suggested that the Northern and Southern Hemisphere climates behave in a seesaw-like fashion: when the northern ocean warms, the southern ocean cools and vice versa. So far, however, the data have indicated a much muted response in Antarctic climate compared to the Arctic. An analysis of new records from an ocean core from the South Atlantic — including planktonic foraminifera assemblages, Mg/Ca ratios, temperature and ocean productivity data — shows that the South Atlantic cooled essentially instantaneously with the warming in the North Atlantic during the last deglaciation. This first concrete evidence of an immediate seesaw connection also provides a link between the rapid warming in the North Atlantic and the more gradual Antarctic response, and suggests a mechanism potentially driving rapid Northern Hemisphere deglaciation.

News and ViewsClimate change: Southern see-saw seen

The bipolar see-saw hypothesis provides an explanation for why temperature shifts in the two hemispheres were out of phase at certain times. The hypothesis has now passed a test of one of its predictions.

Jeffrey P. Severinghaus

doi:10.1038/4571093a

ArticleInterhemispheric Atlantic seesaw response during the last deglaciation

Stephen Barker, Paula Diz, Maryline J. Vautravers, Jennifer Pike, Gregor Knorr, Ian R. Hall & Wallace S. Broecker

doi:10.1038/nature07770