Some common model biases in the Southern Ocean have been identified, resulting in some uncertainty in oceanic heat uptake and transient climate response. (ipcc.ch)
The abstract reads (my boldface): Estimated values of recent oceanic heat uptake are of order of a few tenths of a W / m2, and... (wattsupwiththat.com)
The Southern Ocean plays a dominant role in anthropogenic oceanic heat uptake. (gfdl.noaa.gov)