Until recently, Southern Hemisphere ocean heat content changes were likely underestimated, say researchers.
Lawrence Livermore scientists used a fleet of miniature research vessels (Argo), the global flotilla of more than 3,600 robotic profiling floats, that point towards heating of the upper layers of the world's ocean currents.
The team found that the 3,600 Argo floats currently observing the global oceans, provide systematic coverage of the Southern Hemisphere for the first time. Due to prior poor sampling in the last decade and limitations of the analysis methods that conservatively estimated temperature changes in data, might have been inadequate.
Using satellite observations and a large suite of climate models, have found that long-term ocean warming in the upper 700 meters of Southern Hemisphere oceans has likely been underestimated.
Argo float measurements over the last decade, as well as data from earlier measurements, show that the ocean has been gradually warming.
The observed ocean and atmosphere warming is a result of continuing greenhouse gas emissions. The Southern Hemisphere oceans make up 60 percent of the world's oceans.
The paper appears in the issue of Nature Climate Change journal.