2018 Hottest Ocean Temperatures

Ocean temperatures actually matter more than atmospheric temperatures.

Last year was very likely the hottest year on record, according to the authors of a new study in the journal Science. 

The study examined “multiple lines of evidence from four independent groups” measuring ocean heat and concluded “ocean warming is accelerating.” Researchers found the rate of warming for the upper 2,000 meters of ocean has increased by more than 50 percent since 1991.

As a result, “2018 is shaping up to be the hottest for the oceans as a whole, and therefore for the Earth,” a press release accompanying the study explains.

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“While there still is time to do something to slow this process down, it is too late to stop serious global warming,” study co-author John Abraham, a professor of thermal sciences at the University of St. Thomas in Minnesota, told ThinkProgress,

Abraham warned that global warming “is happening faster than we previously thought.”

Ocean heat content versus CO2 concentrations. CREDIT: Lijing Chen, IAP

“For over a decade, more than 3,000 floats have provided near-global data coverage for the upper 2,000 meters of the ocean,” the study explains. This new Argo system of floating measurement devices provides “superior observational coverage and reduced uncertainties compared to earlier times.”  

These high-quality Argo observations combined with other independent, older ways of measuring OHC, have enabled the authors to provide “the context of the record-breaking recent observations to be properly established.”

Often, most people think of global warming as solely about surface air temperatures. But, as the authors point out, there are two reasons ocean heat content are a much better measure of actual global warming than surface air temperatures, which have traditionally been used to determine what years are the hottest on record.

First, as the study states, the oceans take up “about 93 percent of the Earth’s energy imbalance created by increasing heat-trapping gases in the atmosphere from human activities.” So the overwhelming majority of warming ends up in the oceans.

Second, “ocean heat content is not bothered much by weather fluctuations that do, however, affect the surface temperatures.” And OHC is only “somewhat affected by El Niño events,” which can have a big, short-term impact on surface temperatures.

All of this makes ocean heat content a truer and more stable measure of how fast the Earth is warming under climate change.

Thus, when the data show that 2018 has set the record for ocean heat content, that tells us 2018 sets the record for hottest year.

Another record year.  We're having one record year after another.  Ignoring this will be tragic for our future generations.