[1] We provide updated estimates of the change of ocean heat content and the thermosteric component of sea level change of the 0-700 and 0-2000 m layers of the World Ocean for 1955-2010. Our estimates are based on historical data not previously available, additional modern data, and bathythermograph data corrected for instrumental biases. We have also used Argo data corrected by the Argo DAC if available and used uncorrected Argo data if no corrections were available at the time we downloaded the Argo data.

We provide estimates of the warming of the world ocean for 1955–2008 based on historical data not previously available, additional modern data, correcting for instrumental biases of bathythermograph data, and correcting or excluding some Argo float data. The strong interdecadal variability of global ocean heat content reported previously by us is reduced in magnitude but the linear trend in ocean heat content remain similar to our earlier estimate.

Objectively analysed climatological mean fields of temperature and salinity have been calculated on a 0.25°grid for the World Ocean for the annual, seasonal, and monthly compositing periods using data from the World Ocean Database 2001. The annual and seasonal fields are calculated at standard levels from the surface to 5500 m. The monthly fields are calculated at standard levels from the surface to 1500 m. In comparison with similarly computed climatologies calculated on a 1°grid, ocean circulation features, such as the Gulf of Mexico Loop Current, are more clearly represented. The new 0.25°climatologies preserve most of the spatial resolution of earlier 0.25°temperature and salinity climatologies, while reducing noise by additional smoothing in horizontal space (geographically at each depth), vertically (along depth at each grid), as well as in time (Fourier filtering).

Quality controlled oceanographic profile salinity measurements from the World Ocean Database 2001 (WOD01) were used to calculate linear trends of zonally averaged salinity anomalies for running five year periods from 1955–1959 through 1994–1998 for the World Ocean and the Atlantic, Pacific, and Indian Ocean basins from the surface to 3000 meters depth. Each basin exhibits large‐scale, coherent trends. Most of the Pacific is freshening with the exception of the subtropical South Pacific. The Atlantic exhibits a deep freshening in the subpolar gyre and a shallower, more intense increase in salinity in the tropics and subtropics. The Indian Ocean is becoming more saline at all latitudes in the upper 150 meter layer, with a subsurface freshening between 40°S and the equator in the 250–1000 meter layer. There is freshening in both the Weddell and Ross Seas.