Unabated planetary warming and its ocean structure since 2006

Increasing heat content of the global ocean dominates the energy imbalance in the climate system(1). Here we show that ocean heat gain over the 0-2,000 m layer continued at a rate of 0.4-0.6 W m(-2) during 2006-2013. The depth dependence and spatial structure of temperature changes are described on the basis of the Argo Program's(2) accurate and spatially homogeneous data set, through comparison of three Argo-only analyses. Heat gain was divided equally between upper ocean, 0-500 m and 500-2,000 m components. Surface temperature and upper 100 m heat content tracked interannual El Nino/Southern Oscillation fluctuations(3), but were offset by opposing variability from 100-500 m. The net 0-500 m global average temperature warmed by 0.005 degrees C yr(-1). Between 500 and 2,000m steadier warming averaged 0.002 degrees C yr(-1) 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 forcing(4) and the greater area of the Southern Hemisphere ocean, ocean dynamics also influence regional patterns of heat gain.