Abstract
Increasing heat content of the global ocean dominates the energy imbalance in the climate system1. Here we show that ocean heat gain over the 0â2,000 m layer continued at a rate of 0.4â0.6 W mâ2 during 2006â2013. The depth dependence and spatial structure of temperature changes are described on the basis of the Argo Program's2 accurate and spatially homogeneous data set, through comparison of three Argo-only analyses. Heat gain was divided equally between upper ocean, 0â500 m and 500â2,000 m components. Surface temperature and upper 100 m heat content tracked interannual El Niño/Southern Oscillation fluctuations3, but were offset by opposing variability from 100â500 m. The net 0â500 m global average temperature warmed by 0.005 °C yrâ1. Between 500 and 2,000 m steadier warming averaged 0.002 °C yrâ1 with a broad intermediate-depth maximum between 700 and 1,400 m. Most of the heat gain (67 to 98%) occurred in the Southern Hemisphere extratropical ocean. Although this hemispheric asymmetry is consistent with inhomogeneity of radiative forcing4 and the greater area of the Southern Hemisphere ocean, ocean dynamics also influence regional patterns of heat gain.
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Change history
05 February 2015
In the version of this Letter originally published, in the paragraph beginning 'The large interannual variabilityâ¦' the third sentence should have read: 'The opposing anomalies in the 0â100 and 100â500 m layers are related to El Niño/Southern Oscillation (ENSO) variability in the depth and slope of the equatorial Pacific thermocline3'. This error has been corrected in all versions of the Letter.
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Acknowledgements
The Argo data used here were collected and are made freely available by the International Argo Program and by the national programmes thatcontribute to it. D.R. and J.G., and their part in the Argo Program, were supported by US. Argo through NOAA Grant NA10OAR4310139 (CIMEC/ SIO Argo). J.C., D.M. and S.W. were partly financially supported by the Australian Climate Change Science Program. NOAA_OI_SST_V2 data were provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA. The satellite altimeter SSH products were provided by AVISO with support from the Centre National dâEtudes Spatiales (CNES).
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All co-author (listed alphabetically) contributions were equal, consisting of the three interpolated forms of the Argo data set plus many thoughts, suggestions and revisions improving the manuscript. The first author assembled the interpolated data sets, created the figures and drafted the manuscript.
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Roemmich, D., Church, J., Gilson, J. et al. Unabated planetary warming and its ocean structure since 2006. Nature Clim Change 5, 240â245 (2015). https://doi.org/10.1038/nclimate2513
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DOI: https://doi.org/10.1038/nclimate2513
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