Research Articles Warming of the World Ocean Sydney Levitus, * John I. Antonov, Timothy P. Boyer, Cathy Stephens Warming of the World Ocean -- Levitus et al. 287 (5461): 2225 -- Science We quantify the interannual-to-decadal variability of the heat content (mean temperature) of the world ocean from the surface through 3000-meter depth for the period 1948 to 1998. The heat content of the world ocean increased by ~2 × 1023 joules between the mid-1950s and mid-1990s, representing a volume mean warming of 0.06°C. This corresponds to a warming rate of 0.3 watt per meter squared (per unit area of Earth's surface). Substantial changes in heat content occurred in the 300- to 1000-meter layers of each ocean and in depths greater than 1000 meters of the North Atlantic. The global volume mean temperature increase for the 0- to 300-meter layer was 0.31°C, corresponding to an increase in heat content for this layer of ~1023 joules between the mid-1950s and mid-1990s. The Atlantic and Pacific Oceans have undergone a net warming since the 1950s and the Indian Ocean has warmed since the mid-1960s, although the warming is not monotonic. National Oceanographic Data Center/National Oceanic and Atmospheric Association (NODC/NOAA), E/OC5, 1315 East West Highway, Silver Spring, MD, 20910, USA.