We present new estimates of the variability of ocean heat content based on: a) additional data that extends the record to more recent years; b) additional historical data for earlier years. During 1955–1998 world ocean heat content (0–3000 m) increased 14.5 × 1022 J corresponding to a mean temperature increase of 0.037°C at a rate of 0.20 Wm−2 (per unit area of Earth's total surface area).