Wild fires. Severe storms. Record breaking rains. Heat waves. All occurred in abundance in 2018, and 2018 is shaping up to be the hottest for the oceans as a whole, and therefore for the Earth, in the instrumental record. Global warming is here, and has major consequences already. There is no doubt, none! On January 11, 2019, an important article in Science magazine asks the question about “How fast are the oceans warming?” The subtitle gives the answer: “Observational records of ocean heat content show that ocean warming is accelerating.”

All of these aspects are now very well measured owing to a fairly new ocean observing system called Argo. The network of autonomous profiling floats has now been in place for over 13 years. Also, the quality of older ocean data has been substantially improved, and there are both better and independent methods that account for the sparseness of ocean data before Argo era. Together these advances have enabled quality reconstructions of the past ocean temperature record back to about 1960, enabling the context of the record-breaking recent observations to be properly established. The new article, led by Dr. Lijing Cheng of the Institute of Atmospheric Physics, Chinese Academy of Sciences, highlights how the new observations along with adjusted older records now clearly show not only how the ocean is warming but that the warming is accelerating.

The newly available ocean heat content time series from multiple groups show more consistent but stronger ocean warming since 1960 than previously reported (by the Intergovernmental Panel on Climate Change’s Fifth Assessment Report published in 2013). 2018 is likely to be the hottest year for the oceans on record, beating out 2017 which held the record. 2015 is next warmest, although 2016 was the hottest for the global mean surface temperature, but that was in part because of the huge El Niño event that took place: the extra heat at the surface was at the expense of the ocean which cooled off slightly. By taking up about 93% of the Earth’s energy imbalance created by increasing heat-trapping gases in the atmosphere from human activities, the oceans are the main memory of climate change.

Source: Ocean warming is accelerating