Updated on 29 Mar. 2013
Global Environment and Marine Department
An increase in the globally integrated upper ocean heat content was observed from 1950 to 2012 with a linear trend of 1.99 × 1022 J per decade.
Time series representation of the globally integrated upper (0 – 700 m) ocean heat content anomaly
The 1981 – 2010 average is used as the normal.
The solid line with dots shows the annual mean for the global integrals of upper (0 – 700 m) ocean heat content anomalies. The shaded area indicates a 95% confidence level. These data are updated from Ishii and Kimoto (2009).
The values here may be replaced as new data is obtained.
The globally integrated upper (0 – 700 m) ocean heat content (OHC) increased from 1950 to 2012 at a rate of 1.99 ± 0.30 × 1022 J per decade as a long-term trend with interannual variation (the range indicated by '±' represents a 95% confidence level). Oceans exhibited marked warming from the mid-1990s to the early 2000s, and the warmest conditions on record have been maintained since then. A rise of 0.021 ± 0.003°C per decade in the globally averaged upper (0 – 700 m) ocean temperature accompanied the OHC increase.
The long-term trend can be attributed to global warming caused by increased concentrations of anthropogenic greenhouse gases such as CO2 as well as natural variability. Ocean warming results in higher sea levels due to thermal expansion, and impacts marine ecosystems.