Letter | Published:

Continued global warming after CO2 emissions stoppage

Nature Climate Change volume 4, pages 4044 (2014) | Download Citation


Recent studies have suggested that global mean surface temperature would remain approximately constant on multi-century timescales after CO2 emissions1,2,3,4,5,6,7,8,9 are stopped. Here we use Earth system model simulations of such a stoppage to demonstrate that in some models, surface temperature may actually increase on multi-century timescales after an initial century-long decrease. This occurs in spite of a decline in radiative forcing that exceeds the decline in ocean heat uptake—a circumstance that would otherwise be expected to lead to a decline in global temperature. The reason is that the warming effect of decreasing ocean heat uptake together with feedback effects arising in response to the geographic structure of ocean heat uptake10,11,12 overcompensates the cooling effect of decreasing atmospheric CO2 on multi-century timescales. Our study also reveals that equilibrium climate sensitivity estimates based on a widely used method of regressing the Earth’s energy imbalance against surface temperature change13,14 are biased. Uncertainty in the magnitude of the feedback effects associated with the magnitude and geographic distribution of ocean heat uptake therefore contributes substantially to the uncertainty in allowable carbon emissions for a given multi-century warming target.

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We thank D. Paynter, T. Merlis, K. Rodgers, J. Dunne and N. Gruber for useful discussions and comments. We also thank B. L. Samuels for conducting the GFDL ESM2M simulations and R. Roth for help with the impulse response function calculations. Simulations with the NCAR CSM1 were carried out at the University of Bern, Switzerland. T.L.F. acknowledges financial support from the SNSF (Ambizione grant PZ00P2_142573). J.L.S. was supported by the Carbon Mitigation Initiative (CMI) project at Princeton University, sponsored by BP.

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  1. Environmental Physics, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich, 8092 Zürich, Switzerland

    • Thomas Lukas Frölicher
  2. Program in Atmospheric and Oceanic Sciences, Princeton University, Princeton, New Jersey 08544, USA

    • Thomas Lukas Frölicher
    •  & Jorge Louis Sarmiento
  3. Geophysical Fluid Dynamics Laboratory, National Oceanic and Atmospheric Administration, Princeton, New Jersey 08542, USA

    • Michael Winton


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T.L.F. and M.W. designed the study and undertook main analysis. T.L.F. performed simulations and wrote the paper, with significant text supplied by all authors, who also discussed the results.

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The authors declare no competing financial interests.

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Correspondence to Thomas Lukas Frölicher.

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