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


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