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Ocean Science An interactive open-access journal of the European Geosciences Union
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Volume 12, issue 4 | Copyright
Ocean Sci., 12, 925-935, 2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 26 Jul 2016

Research article | 26 Jul 2016

Observed and simulated full-depth ocean heat-content changes for 1970–2005

Lijing Cheng1, Kevin E. Trenberth2, Matthew D. Palmer3, Jiang Zhu1, and John P. Abraham4 Lijing Cheng et al.
  • 1International Center for Climate and Environment Sciences, Institute of Atmospheric Physics, Chinese Academy of Sciences, 100029, Beijing, China
  • 2National Center for Atmospheric Research, Boulder, CO, USA
  • 3Met Office Hadley Centre, FitzRoy Road, Exeter, EX1 3PB, UK
  • 4School of Engineering, University of St. Thomas, St. Paul, MN, USA

Abstract. Greenhouse-gas emissions have created a planetary energy imbalance that is primarily manifested by increasing ocean heat content (OHC). Updated observational estimates of full-depth OHC change since 1970 are presented that account for recent advancements in reducing observation errors and biases. The full-depth OHC has increased by 0.74 [0.68, 0.80] × 1022Jyr−1 (0.46Wm−2) and 1.22 [1.16–1.29] × 1022Jyr−1 (0.75Wm−2) for 1970–2005 and 1992–2005, respectively, with a 5 to 95% confidence interval of the median. The CMIP5 models show large spread in OHC changes, suggesting that some models are not state-of-the-art and require further improvements. However, the ensemble median has excellent agreement with our observational estimate: 0.68 [0.54–0.82] × 1022Jyr−1 (0.42Wm−2) from 1970 to 2005 and 1.25 [1.10–1.41] × 1022Jyr−1 (0.77Wm−2) from 1992 to 2005. These results increase confidence in both the observational and model estimates to quantify and study changes in Earth's energy imbalance over the historical period. We suggest that OHC be a fundamental metric for climate model validation and evaluation, especially for forced changes (decadal timescales).

Publications Copernicus
Short summary
A new method of observing ocean heat content throughout the entire ocean depth is provided. The new method is compared with simulated ocean heat content changes from climate models. The comparisons are carried out in various depth layers of the ocean waters. It is found that there is excellent agreement between the models and the observations. Furthermore, we propose that changes to ocean heat content be used as a fundamental metric to evaluate climate models.
A new method of observing ocean heat content throughout the entire ocean depth is provided. The...