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Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation



The covariation of carbon dioxide (CO2) concentration and temperature in Antarctic ice-core records suggests a close link between CO2 and climate during the Pleistocene ice ages. The role and relative importance of CO2 in producing these climate changes remains unclear, however, in part because the ice-core deuterium record reflects local rather than global temperature. Here we construct a record of global surface temperature from 80 proxy records and show that temperature is correlated with and generally lags CO2 during the last (that is, the most recent) deglaciation. Differences between the respective temperature changes of the Northern Hemisphere and Southern Hemisphere parallel variations in the strength of the Atlantic meridional overturning circulation recorded in marine sediments. These observations, together with transient global climate model simulations, support the conclusion that an antiphased hemispheric temperature response to ocean circulation changes superimposed on globally in-phase warming driven by increasing CO2 concentrations is an explanation for much of the temperature change at the end of the most recent ice age.

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Figure 1: Proxy temperature records.
Figure 2: CO 2 concentration and temperature.
Figure 3: Global temperature and climate forcings.
Figure 4: Hemispheric temperatures.
Figure 5: Temperature change before increase in CO 2 concentration.


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Discussions with numerous people, including E. J. Brook, A. E. Carlson, N. G. Pisias and J. Shaman, contributed to this research. We acknowledge the palaeoclimate community for generating the proxy data sets used here. In particular, we thank S. Barker, T. Barrows, E. Calvo, J. Kaiser, A. Koutavas, Y. Kubota, V. Peck, C. Pelejero, J.-R. Petit, J. Sachs, E. Schefuß, J. Tierney and G. Wei for providing proxy data, and R. Gyllencreutz and J. Mangerud for providing unpublished results of the DATED Project on the retreat history of the Eurasian ice sheets. The NOAA NGDC and PANGAEA databases were also essential to this work. 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 no. DE-AC05-00OR22725. NCAR is sponsored by the NSF. J.D.S. is supported by a NOAA Climate and Global Change Postdoctoral Fellowship. This research was supported by the NSF Paleoclimate Program for the Paleovar Project through grant AGS-0602395.

Author information




J.D.S. designed the study, synthesized and analysed data, and wrote the manuscript with P.U.C. F.H., Z.L. and B.O.-B. did the transient modelling. S.A.M. and A.C.M. contributed to data analysis. A.S. helped interpret AMOC–CO2 linkages. E.B. provided data and discussion on the radiocarbon calibration. All authors discussed the results and provided input on the manuscript.

Corresponding author

Correspondence to Jeremy D. Shakun.

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The authors declare no competing financial interests.

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Shakun, J., Clark, P., He, F. et al. Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation. Nature 484, 49–54 (2012).

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