As El Nino Emerges, Ominous Findings on Ocean Heat

March 31, 2015

This map shows trends in global ocean heat content, from the surface to 2,000 meters deep.


Yale Environment 360:

Scientists are also learning that the ocean has gained more heat, and at greater depth, than they had realized. That means the entire climate is even more out-of-whack than is evident today.

“If you want to measure the energy imbalance of the earth, the ocean temperature gives you nearly the whole story,” said Dean Roemmich, oceanography professor at the University of California San Diego’s Scripps Institution of Oceanography,

The long-term heat gain in the top 700 meters (.43 miles) of the world’s oceans has likely been underestimated by as much as half, according to Lawrence Livermore National Laboratories research scientist Paul Durack. Earlier measurements had lowballed heat accumulation due to historically sparse observations for large parts of the ocean. The figures were especially low for the Southern Hemisphere, which contains about 60 percent of the planet’s oceans but was very poorly sampled — until Argo, an array of around 3,500 floating sensors, was deployed worldwide in 2005.

An updated analysis by Durack and colleagues found that from 1970 to 2004, the upper 700 meters of oceans in the Southern Hemisphere had gained from 48 to 166 percent more heat than earlier observations had estimated. Globally, the findings suggest, upper oceans hold 24 to 58 percent more heat than most current climate models assumed.

“We have likely been missing a portion of the heat,” said Durack. His study and other recent research, he said, suggests that “we may need to go back and start recalculating the climate sensitivity estimates of the earth.”

Excess energy is also penetrating deeper into the ocean and farther south, Roemmich and colleagues found, analyzing Argo data measuring heat down to 2,000 meters (1.24 miles). The network provides the first comprehensive measurements of the deeper ocean; most prior readings stopped at 700 meters. The researchers found that from two-thirds to 98 percent of the substantial ocean heat gain between 2006 and 2013 took place well south of the equator, where giant gyres drew it down. And half of the gain occurred from 500 to 2,000 meters deep.

Roemmich estimates that at depths from 500 to 2000 meters, oceans are warming by .002 degrees Celsius every year, and in the top 500 meters, they’re gaining .005 degrees C. annually. While that may not seem like a big temperature jump, it amounts to a staggering load of heat when multiplied throughout the depths of this immense system that covers 70 percent of the planet.

Temperature gains are larger at the sea surface, which heats faster than the ocean as a whole. The top 75 meters have warmed an average of .01 degrees C per year since 1971. But forces like winds and currents have strong effects on the ocean surface, and temperature measurements there are highly variable. Still, they indicate that some areas of the ocean are heating up especially fast, such as the Arctic Ocean — which this year had its lowest winter ice year on record — and is absorbing much more solar energy as melting ice cover exposes new dark surfaces. Summer sea surface temperatures in some sections have risen around 1 degree C over the past two decades — nearly five times the global average. Parts of the Indian Ocean, North Atlantic, and waters surrounding Antarctica are warming at nearly the same rate.

More heat stored in the ocean now means more will inevitably return to the atmosphere.

“A couple of El Niño events will do the trick,” said England. The warm water and calm winds of this periodic Pacific tropical condition are “a big way to get subsurface heat back to the surface.” Meteorologists say a mild El Niño condition is underway this year.

Scientific American:

Scientists have been measuring the heat in the warming upper layers since the 1970s, but these measurements have not been very accurate. The Southern Hemisphere’s oceans, especially, have been a dark spot.

So to cross-check the heating of the oceans, Durack of LLNL and his colleagues took a roundabout route. They first verified that climate models are accurate using real-world satellite data of sea-level rise. Then they used the climate models to simulate by how much ocean heat content has risen since the 1970s.

Their simulations did not agree with measurements of ocean heat made by scientists since the 1970s, particularly in the Southern Hemisphere. Prior to the Argo initiative, very few measurements were taken in the south, said John Abraham, a professor at the University of St. Thomas in St. Paul, Minn., who was not involved in the study.

“They find the warming of the ocean since 1970 is biased low,” he said, “which means there really was more warming than we’ve thought.”

Since the advent of the Argo project, the measurements have improved and the ocean’s heat content has matched the predictions of climate models, Durack said.
The Durack paper suggests that the upper oceans have been warming much more rapidly over the past 35 years than previously thought.


13 Responses to “As El Nino Emerges, Ominous Findings on Ocean Heat”

  1. dumboldguy Says:

    Is there NO good news? It would be great if someone would announce for a change that some finding was “biased high” and that things weren’t as bad as they appeared.

    Instead, we have lately had a constant stream of announcements that the partially unknown knowns are now more fully known knowns, and it’s all pointing in a negative direction.

  2. Toni Palmén Says:

    It seems that the “worse than thought” is the current trend. Nobody wants to be the one “crying wolf”, even as the werewolf is just around the corner. So they underestimate everything. I’m kinda inclined to think that Guy McPherson maybe isn’t that far off from the truth with his pessimistic(?) estimates…

  3. Linda Plano Says:

    The only “good” news is that, as evidence mounts, the denier numbers will dwindle, even as the core hardens, and that means critical mass for doing something increases.

    I know, it’s not much (I was doing research to make cost-effective GaAs solar cells in 1983, so I can well appreciate the opportunity cost of waiting for consensus) and it’s not data, but I do think 2015 is the year that history may highlight as the time when the world shifted toward being proactive.

    • climatehawk1 Says:

      Exactly right. No good news, other than that the moment of truth is approaching (which I guess is better than if it occurs after we’ve laid in 8 or 10 degrees C of future warming).

  4. ubrew12 Says:

    Trenberth (Climategate): “The fact is that we can’t account for the lack of warming at the moment and it is a travesty that we can’t.”
    What are the chances Faux News and WUWT are going to spread the good news that Trenberth’s missing heat is being found, in the ocean where he suspected it would be found? Slim to none (it doesn’t support the ‘doubt is our product’ propaganda they are selling).

  5. Gingerbaker Says:

    I hate to say it, but the science community has done a less than stellar job presenting this whole issue to the public. The “pause” has been called a pause by those who should know better, and nobody has done a proper accounting for the missing calories.

    Those calories are either not included in Arctic areas, or an artifact of unadjusted previous measurements, or to be found in the first 700 meters of ocean, or maybe in the sea from 700-2000 meters down. Or something.

    This guy did a better job accounting for calories:


  6. […] As El Nino Emerges, Ominous Findings on Ocean Heat (Climate Crocks): Scientists are also learning that the ocean has gained more heat, and at greater depth, than they had realized. That means the entire climate is even more out-of-whack than is evident today. […]

  7. indy222 Says:

    Peter, your summaries of SciAm and Yale360 fail to include that Kevin Trenberth finds the associated Josh Willis et al work “deeply flawed” (although I can only find media reports that Trenberth says this, not the original source, alas). Trenberth et al find the deep oceans ARE taking up significant heat during the past ~18 years “pause”, and Willis’ subtraction method finds it is not. More data from the new Deep Argo fleet now being deployed, should resolve this.

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