# Greater committed warming after accounting for the pattern effect

## Abstract

Our planet’s energy balance is sensitive to spatial inhomogeneities in sea surface temperature and sea ice changes, but this is typically ignored in climate projections. Here, we show the energy budget during recent decades can be closed by combining changes in effective radiative forcing, linear radiative damping and this pattern effect. The pattern effect is of comparable magnitude but opposite sign to Earth’s net energy imbalance in the 2000s, indicating its importance when predicting the future climate on the basis of observations. After the pattern effect is accounted for, the best-estimate value of committed global warming at present-day forcing rises from 1.31 K (0.99–2.33 K, 5th–95th percentile) to over 2 K, and committed warming in 2100 with constant long-lived forcing increases from 1.32 K (0.94–2.03 K) to over 1.5 K, although the magnitude is sensitive to sea surface temperature dataset. Further constraints on the pattern effect are needed to reduce climate projection uncertainty.

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## Data availability

All observational data and AMIP-piForcing experiment data in Table 1 are publicly available online, as described in Methods. In addition, results of the idealized experiments carried out in this study are available from the corresponding author upon request.

## Code availability

The code of CESM1.2-CAM5.3 model used in this paper can be downloaded from http://www.cesm.ucar.edu/models/cesm1.2/. Codes for plotting figures are available from the corresponding author upon request.

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## Acknowledgements

C.Z. was supported by NSFC grant no. 41875095. A.E.D. was supported by NSF grant nos. AGS-1661861 and AGS-1841308, both to Texas A&M University. M.D.Z. worked under the auspices of the US Department of Energy (DOE), Lawrence Livermore National Laboratory under contract no. DE-AC52-07NA27344 and was supported by the Regional and Global Model Analysis Program of the Office of Science at the DOE. M.W. was supported by Minister of Science and Technology of China grant nos. 2017YFA0604002 and 2016YFC0200503, and NSFC grant nos. 91744208, 41575073 and 41621005. This research is also supported by the Collaborative Innovation Center of Climate Change, Jiangsu Province. The numerical simulations in this paper were done on the computing facilities in the High Performance Computing Center of Nanjing University. Correspondence and requests for materials should be addressed to C.Z.

## Author information

Authors

### Contributions

C.Z. performed the analysis. The paper was discussed and written by all authors.

### Corresponding author

Correspondence to Chen Zhou.

## Ethics declarations

### Competing interests

The authors declare no competing interests.

Peer review information Nature Climate Change thanks Jonah Bloch-Johnson, Diego Jiménez-de-la-Cuesta and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Zhou, C., Zelinka, M.D., Dessler, A.E. et al. Greater committed warming after accounting for the pattern effect. Nat. Clim. Chang. (2021). https://doi.org/10.1038/s41558-020-00955-x