Antarctic ice cores show that a millennial-scale cooling event, the Antarctic Cold Reversal (14,700 to 13,000 years ago), interrupted the last deglaciation1,2,3. The Antarctic Cold Reversal coincides with the Bølling–Allerød warm stage in the North Atlantic, providing an example of the inter-hemispheric coupling of abrupt climate change generally referred to as the bipolar seesaw4,5,6,7,8,9. However, the ocean–atmosphere dynamics governing this coupling are debated10,11,12,13,14,15. Here we examine the extent and expression of the Antarctic Cold Reversal in the Southern Hemisphere using a synthesis of 84 palaeoclimate records. We find that the cooling is strongest in the South Atlantic and all regions south of 40° S. At the same time, the terrestrial tropics and subtropics show abrupt hydrologic variations that are significantly correlated with North Atlantic climate changes. Our transient global climate model simulations indicate that the observed extent of Antarctic Cold Reversal cooling can be explained by enhanced northward ocean heat transport from the South to North Atlantic10, amplified by the expansion and thickening of sea ice in the Southern Ocean. The hydrologic variations at lower latitudes result from an opposing enhancement of southward heat transport in the atmosphere mediated by the Hadley circulation. Our findings reconcile previous arguments about the relative dominance of ocean5,10,11 and atmospheric14,15 heat transports in inter-hemispheric coupling, demonstrating that the spatial pattern of past millennial-scale climate change reflects the superposition of both.
Access optionsAccess options
Subscribe to Journal
Get full journal access for 1 year
only $16.50 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
This work is a contribution to INQUA PALCOMM project 1302 SHAPE: Southern Hemisphere Assessment of PalaeoEnvironments. J.B.P. acknowledges support from the Joint Institute for the Study of the Atmosphere and Ocean (JISAO Contribution No. 2408) and from a Marie Curie International Incoming Fellowship. H.C.B. was funded by NIWA core funding (COPR). G.C. and M.J.V. were supported by the New Zealand Government through the GNS Global Change through Time Program. C.M.B. received support from NSF PLR 1341497. F.H. is supported by the US NSF and the US NOAA Climate and Global Change Postdoctoral Fellowship Program. This research used resources of the Oak Ridge Leadership Computing Facility, located in the National Center for Computational Sciences at Oak Ridge National Laboratory, which is supported by the Office of Science of the Department of Energy under contract DE-AC05-00OR22725. B.M.C. was funded by the European Research Council (ERC) under the European Union’s Seventh Framework Programme (FP7/2007-2013)/ERC Starting Grant ‘HYRAX’, grant agreement no. 258657. We thank D. Battisti, S. Schoenemann, D. Frierson, A. Lorrey, T. Barrows, A. Mackintosh and M. Mudelsee for helpful discussions. We also thank the many researchers who provided data sets for this work.