2010-09-22 13:12:06Ocean heat revisited
John Cook


I think it's time to revisit the ocean heat issue. Doug Bostrom expressed interest in writing a blog post about this but I thought I'd start a thread so people can kick some ideas around. For starters, a new study finds deep ocean warming in the Southern Ocean: Scientists Find 20 Years of Deep Water Warming Leading to Sea Level Rise. Doug knows one of the authors of this paper.

Secondly, there is a new "skeptic" peer-reviewed paper Recent energy balance of Earth (full PDF). This takes the same line of thinking of Pielke - oceans are cooling, thus the planet has a negative energy imbalance thus no global warming. Unsurprisingly, Pielke is very keen on this paper (note the link to Graham's post).

I suggest you all have a read through the PDF - it's a very short paper. Basically, it asserts that the oceans are cooling using ocean heat reconstructions by themselves, Willis, Loehle (who used Willis' data), Pielke and von Schuckmann. The 4 reconstructions done by skeptics all show cooling, von Schuckmann shows warming. They profess no idea on why von Schuckmann is the "outlier". I can't see any reference to the phrase "upper ocean heat" so they make no distinction between the 4 cooling estimates which I presume are of the upper 700 metres and von Schuckmann which goes down to 2000 metres.

What I find most weird about this paper is they don't include Lyman 2010 in their estimates - which I would consider the most authoritative estimate to date (in what is nevertheless still a very uncertain dataset). After all, this is the paper where all the major ocean labs got together, compared notes and produced a definitive ocean heat estimate (here's my blog post on this paper). Perhaps this is because Lyman 2010 finds a warming trend (albeit flatter than earlier warming trends but certainly not cooling):

Upper ocean heat content anomaly

Note to Doug: they do make a reference to the Johnson paper, saying it only finds 0.009 W/m2, not enough to account for the missing heat.

Then there is also Ari's proposed post on NODC ocean heat where he discussed the uncertainties in the Argo data. That's pertinent to this discussion too.

So lots there to chew on. Discuss :-)

2010-09-22 19:39:15
Rob Painting

John, Strange title for that paper when it only addresses OHC data over a short time frame. I like this bit:

There are two different observational systems for determining OHC. The first and older is based upon expendable bathythermograph (XBT) probes that have been shown to have various biases and systematic errors (Wijffels et al. [3]). The second is the more accurate and complete global array of autonomous Argo floats [4], which were deployed as of the early 2000s. These floats are free from the biases and errors of the XBT probes although they have had other systematic errors

So yeah, the ARGO are more accurate because they have different systematic errors and biases? As for Von Schuckmann they do mention it measures down to 2000 mtrs just above the outlier comment. And you know why Lyman wasn't included -it's a tad inconvenient. Guess it must be pixie dust that's causing the global sea levels to rise & the earth to continue warming. Mind you, I see Douglass has another unusual paper out recently, something about phase locked climate states?.

One question - I see estimates like those of Hansen et al 2005 , that the thermal lag of the global oceans, depending on actual climate sensitivity could be in the order of a century, any idea what time lag the top 750 meters represents?.

2010-09-22 19:42:55


Indeed I'm working on a blog post about the new Purkey/Johnson paper. It's "a big f-----g deal" as US Vice President Biden might say. Full text here http://www.pmel.noaa.gov/people/gjohnson/Recent_AABW_Warming_v3.pdf and worth reading as an example of circumspect treatment quite apart from the vast quantity of heat described. 

Blog post under construction here: http://www.skepticalscience.com/thread.php?t=198&r=0 

As to "only finds 0.009 W/m2, not enough to account for the missing heat." Douglass is only off by an order of magnitude. In fact some 20% of "missing" heat appears to be accounted for in Purkey/Johnson:

"The recent decadal warming of the abyssal global ocean below 4000 m is equivalent to a

global surface energy imbalance of 0.027 (±0.009) W m–2 with Southern Ocean deep

warming contributing an additional 0.068 (±0.062) W m–2 from 1000–4000 m. "

Oops.  20% is a substantial improvement in the budget. 

2010-09-22 20:37:34
Ari Jokimäki


John: "Then there is also Ari's proposed post on NODC ocean heat where he discussed the uncertainties in the Argo data. That's pertinent to this discussion too."

Note also the things I said about AchutaRao et al. (2007) in the discussion of my post here:

They make an important point about the differences with ocean heat content and volume-averaged temperature. It would be nice to find a more elaborate discussion on that issue, though.

Oh, and I wrote about Purkey & Johnson too:

2010-09-22 21:13:13
Ari Jokimäki


This paper might also be important (Roemmich & Gilson, 2009):


Roemmich is in the Argo steering team so perhaps this is "official" Argo paper. In the end of the paper they say about trends:

"Other recent studies have estimated interannual variability and trends in globally averaged Argo temperature or steric height (e.g. Willis et al., 2008; Cazenave et al., 2009). These are important issues, but the Argo dataset will take some years, and careful comparison to all available shipboard CTD measurements, to achieve its best quality and to have that quality assessed. The studies to date demonstrate that there is still substantial uncertainty in closure of the sea level budget on the 5-year timescale for which Argo, satellite altimetry, and satellite gravimetry presently overlap. A longer period of time is needed both to analyze and reduce the systematic errors in these measurements, and for the modest trends in the component estimates to stand out above the remaining errors."

According to Pierce et al. (2006), this paper (Gregory et al., 2004) discusses data infilling problems in ocean heat content analysis but I only found the abstract for this one:


2010-09-22 21:36:52Ari and Doug blog posts
John Cook

Ari, perhaps have a look at Doug's thread where he's posted a draft of his blog post - if you're interested, perhaps your post (or combination of the two posts you did) could complement it? Just a thought.
2010-09-22 21:44:05
Ari Jokimäki


Ok, about the new paper by Knox & Douglass. Their take on Argo problems is very weak. They only refer to Willis et al. (2007) correction to their original 2006 cooling-paper. Willis et al. (2008) paper on the problems is not included to their reference list. In my opinion, they try to paint far too rosy picture of Argo data.

2010-09-22 22:43:44To be fair...
James Wight

In fairness, Lyman 2010 was published relatively recently and maybe that's why it's not included in the new paper.
2010-09-22 23:40:00
Ari Jokimäki


This new paper by Knox & Douglass does discuss the Lyman et al. (2010).

2010-09-23 02:01:23useless paper
Dana Nuccitelli

For the record, Knox and Douglass got Purkey and Johnson right.

"We note that one recent deep-ocean analysis [16], based on a variety of time periods generally in the 1990s and 2000s, suggests that the deeper ocean contributes on the order of 0.09 W/m2.  This is not sufficient to explain the discrepancy."

I find their paper rather useless though, and poorly done.  Basically they argue that using ARGO data only (and ignoring Lyman [2010]), the upper oceans cooled over a 5-year period.  Whoopdy-doo.  They also basically ignore von Schuckmann other than referencing his results briefly, as the conclusion of Knox and Douglass is "In summary, we find that estimates of the recent (2003–2008) OHC rates of change are preponderantly negative."

Frankly that conclusion ticks me off.  The only negative values are in the upper 700 meters.  von Schuckmann is +0.68 W/m2, and Purkey and Johnson is an additional  0.09 W/m2.  If anything their conclusion should refer to upper OHC, not OHC as a whole, and only over a 5 year period.  That's garbage.  I think it's terrible that this wording made it through peer-review.  Reminds me of the McLean and Carter paper that snuck through the conclusion that ENSO was causing global warming, even though their research didn't support that conclusion in the least, and was very quickly disproven by another paper with Annan as co-author (I forget who the lead on that one was).

Coincidentally, Douglass was also the lead author on the horribly flawed 'no tropical troposphere hot spot' paper which was later demolished by Santer et al. (2008), and discussed several times by RealClimate.  I think Douglass is making a rather bad reputation for himself.

2010-09-23 04:48:45


Dana: I think Douglass is making a rather bad reputation for himself.

Leaping from discipline to discipline like a scalded cat. How likely is it that we'll get anything worthwhile from an attention deficit disorder like that? 

2010-09-23 06:04:11


I don't think we should write (or update) a post on OHC including this paper, a specific rebuttal of the paper is more appropiate. It's a lot more work and the first step is replicate his analysis on the same data, which we do not have. Maybe John (now famous between scientists ;)) may ask Willis or the ARGO team for the data and a comment on the paper.

Just a few words to highlight the intrisically misleading nature of this paper. Using NODC data (the same used by Knox et al.)  the 2003-2009 trend is almost zero (0.009 W/m2) but not statistically significant; the 2002-2009 trend is 0.23 W/m2 and statistically significant. 

2010-09-23 09:15:27Excerpt from Planet 3.0 thread
John Cook


The planet 3.0 bloggers are discussing this subject as well, particularly the paper on deep ocean warming. I'm just going to reproduce an interesting comment from Bob Grumbine which provides some insights:

I'm not sure that the 'missing' heat was ever really missing.    But, yes, the deep ocean is a handy place to bury some heat that will be hard to get good measurements on.

The places you can put the heat are air (lousy place, it's a small reservoir and radiates easily to space), land (also lousy -- low thermal conductivity, so low reservoir), ice (melting ice can soak up a ton of heat; but little of the earth is ice-covered) and ocean (enormous heat sink -- 2.5 meters of ocean have the same heat capacity as the entire atmospheric column above it; average depth of the ocean = 3730 meters).

Within the ocean we can split it further, between the upper mixed layer (loosely speaking, the upper 50-100 meters that is thoroughly mixed by winds, thence more or less well-sampled by surrface temperature observations),  above the permanent thermocline (loosely speaking, above 1000 meters) where circulation processes in the upper ocean do some fair mixing and spreading of energy (note that the article talks about 'below 3300 feet' -- 1000 m), but until Argo we have few direct measurements.  Then below 1000 meters, the 'deep' ocean'.

The good news regarding trying to observe the deep ocean for buried heat is that 'new' water only enters the deep ocean (dives below 1000 meters) in a handful of places, almost all of which are geographically limited*.  Once down there, the water stays for a very long time (centuries and up in the modern ocean).

The Antarctic Bottom Water  (AABW) is not a good place to store your heat for long term.  Warming the water makes it less dense, so less able to sink to the deep ocean.  An important part of making AABW is making water salty (the High Salinity Shelf Water method, and topic of my soon-to-be 21 year old thesis).  So the mechanism can withstand some heating -- as long as enough sea ice freezes near the Antarctic coast.  But, once the water gets warm enough either the sea ice freezing slows down, or the densification isn't enough, and you turn off the burial of heat in the deep Antarctic ocean.

*The major exception is Antarctic Intermediate Water, which sinks around all of Antarctica.  It's limited in latitude span, but it's a full 360 degrees of longitude.

So I still don't know about 'missing heat', but it's an interesting addition to what we know about the Antarctic deep ocean circulation.  
2010-09-23 09:17:27Re contacting scientists
John Cook

Riccardo, re contacting scientists, I'm actually working on something more general that I hope will involve scientists more in writing rebuttals here - but I want to get it all organised and do it properly to maximise the chances of a response (the greatest difficulty will be enticing busy scientists to take the time to be involved).