Even More about Trenberth’s Missing Heat – An Eye Opening Comment by Roger Pielke Sr.

Roger Pielke Sr. was quoted in David Appell’s recent article Whither global warming?  Has global warming slowed down? over at the Yale Forum on Climate Change & The Media. That portion of the article reads:

About 90 percent of this extra energy goes into the oceans. But meteorologist Roger Pielke Sr. of the University of Colorado in Boulder says he would like to understand why more heat is going into the deep ocean. “Until we understand how this fundamental shift in the climate system occurred,” says Pielke, “and if this change in vertical heat transfer really happened, and is not just due to the different areal coverage and data quality in the earlier years, we have a large gap in our understanding of the climate system.”

These large changes in ocean content reveal that the Earth’s surface is not a great place to look for a planetary energy imbalance. “This means this heat is not being sampled by the global average surface temperature trend,” he says. “Since that metric is being used as the icon to report to policymakers on climate change, it illustrates a defect in using the two-dimensional field of surface temperature to diagnose global warming.”

David Appell’s entire article about the recent pause in global warming is worth a read. It was also the topic of Judith Curry’s post more on the ‘pause’. There, in a comment yesterday, Roger Pielke Sr. provided his complete answer to David Appell’s interview question. Roger was also kind enough to email me his full reply with the italics, underlined and boldface text intact.  It’s as follows:

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 Hi David

 Here is my reply to your question

What do you think of Trenberth’s recent paper on ocean warming (attached)?

Balmaseda et al, Distinctive climate signals in reanalysis of

global ocean heat content, GRL

They obtain an ocean warming, for 2000-2009, of 1.19 W/m2.

Does that change any of your concerns about models overestimating net

radiative forcing, such as you wrote in Physics Today in 2007 (also

attached)?

My Answer

1. The recognition that ocean heat content changes can be used to diagnose the global radiative imbalance in Watts per meter squared, that I discussed in my paper

Pielke Sr., R.A., 2003: Heat storage within the Earth system. Bull. Amer. Meteor. Soc., 84, 331-335. http://pielkeclimatesci.files.wordpress.com/2009/10/r-247.pdf

is applied in the Balmaseda et al 2013 paper. This, as I reported in my Physics Today article, is the much more robust approach to assess global warming and cooling, than using the global annual average surface temperature trend.

The Balmaseda et al paper is a step forward in understanding the changes of heat content.

2. However, there are substantive, unanswered questions that their paper introduces.

(i) First, they report that

“In the last decade, about 30% of the warming has occurred below 700 m.”

This change in heat content is a marked difference from what they report for the earlier years as illustrated in their Figure 1. They can only speculate on how this could have occurred; i.e. they write [boldfaced highlight added]

“….that changes in the atmospheric circulation are instrumental for the penetration of the warming into the ocean, although the mechanisms at work are still to be established. One possibility suggested by Lee and McPhaden [2008], is related to the modified subduction pathways in response to changes in the subtropical gyres resulting from changes of the trade winds in the tropics (Figure S04), but whether as low frequency variability or a longer term trend remains an open question. The 2000–2006 warming trend is likely associated with the weakening of the Atlantic Meridional Overturning Circulation (MOC) in both experiments (see BMW13).”

Until we understand how this fundamental shift in the climate system occurred  (and if this change in vertical heat transfer really happened, and is not just due to the different areal coverage and data quality in the earlier years), however, we have a large gap in our understanding of the climate system.

(ii)  Moreover, how could this heat be transferred to depths below 700m without being been seen in the upper 700m of the ocean? [and this is a question also on the transfer of heat to between 300m and 700m without being seen in the upper 300m].

This absence of observable heat transfer through the upper 300m of the ocean is an issue that must be resolved.

3. There are also major implications for their findings even if they are robust.

(i) First, they report on a rate of heating that reads

the latest decade being significantly higher (1.19 ± 0.11 W m-2).

While, this is larger than found in the past,  it is still less than the best estimate of the global average radiative forcing reported in the IPCC 2007 report (1.6 ± 0.6 to 2.4 W m-2 total net anthropogenic plus  0.12 ±  0.06 to 0.30 W m-2 from solar irradiance changes).

Since their reported diagnosed radiative imbalance for the last decade is 1.19 ± 0.11 W m-2 –  which includes both the radiative forcings and all of the feedbacks (including from water vapor), this indicates that either the IPCC best estimate of the total radiative forcings by the IPCC is in error, and/or the radiative feedbacks in the climate system are a net negative.

(ii) Another very significant conclusion of their study, if it is correct, is that when they report that

about 30% of the warming has occurred below 700 m.

[and from their Figure 1, the percentage below 300m since 2003 is clearly well above 50%!]

this means that this heat is not being sampled by the global average surface temperature trend.

Since that metric is being used as the icon to report to policymakers on climate change (i.e. paraphrasing from other sources “we need to remain below a +2C change”), it illustrates a defect in using the two dimensional field of surface temperature to diagnose global warming.

 I discuss this in my post

Torpedoing Of The Use Of The Global Average Surface Temperature Trend As The Diagnostic For Global Warming. http://pielkeclimatesci.wordpress.com/2011/09/20/torpedoing-of-the-use-of-the-global-average-surface-temperature-trend-as-the-diagnostic-for-global-warming/

(iii)  Moreover, they write,

“La Niña events and negative PDO events could cause a hiatus in warming of the top 300 m while sequestering heat at deeper layers.”

If this is a real effect, than this is a muting of the radiative effect as this deep layer warming is unlikely to be reemitted back into the atmosphere in short time periods in large amounts (of Joules) as it would diffuse horizontally and vertically, at depth, in the ocean.

(iv) Also, the latest real world measurement of upper ocean heat content; [see the attachment in my e-mail from http://oceans.pmel.noaa.gov/]  continues to show, little if any significant recent warming.

(v) Finally, with respect to the change in slope, this occurred when the ARGO network achieved world-wide coverage. This raises the suspicion  that it is the date quality and coverage that remains more of an issue before 2003 than concluded in Balmaseda et al paper when they excluded the ARGO data.

Please let me know if you have any follow up questions. Thank you for the opportunity to comment.

Best Regards

Roger Sr.

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CLOSING

When Roger wrote [my boldface]…

Until we understand how this fundamental shift in the climate system occurred (and if this change in vertical heat transfer really happened, and is not just due to the different areal coverage and data quality in the earlier years), however, we have a large gap in our understanding of the climate system.

…the following graphs from the post NODC’s Pentadal Ocean Heat Content (0 to 2000m) Creates Warming That Doesn’t Exist in the Annual Data – A Lot of Warming came to mind.

Kind of odd that the NODC’s annual ocean heat content data for 0-2000 meters, Figure 1, should warm hand in hand with the data for 0-700 meters from 1970 to 2003.

Figure 1

But then as soon as the ARGO floats are deployed and have close to full coverage of the global oceans, the datasets diverge, Figure 2.

Figure 2

Does anyone want to speculate about why the NODC removed their long-term annual ocean heat content for the depths of 0-2000 meters from their website?