2010-08-22 19:36:31Basic Rebuttal No. 27: Oceans Are Cooling REVISION 1
Graham Wayne

Ocean cooling: denialist arguments drowned by data

Argument 27: Oceans Are Cooling

In 2008, climate change sceptic Roger Pielke Sr said this: “Global warming, as diagnosed by upper ocean heat content has not been occurring since 2004”. It is a fine example of denialist spin, making several extraordinary leaps:

  • that one symptom is indicative of the state of an entire malaise (e.g. not being short of breath one day means your lung cancer is cured).
  • that one can claim significance about a four year period when it’s too short to draw any kind of conclusion
  • that global warming has not been occurring on the basis of ocean temperatures alone

So much for the hype. What does the science say about the temperature of the oceans – which, after all, constitute about 70% of the Earth’s surface? The oceans store approximately 80% of all the energy in the Earth’s climate, so ocean temperatures are a key indicator for global warming.

No straight lines

Claims that the ocean has been cooling are correct. Claims that global warming has stopped are not. It is an illogical position: the climate is subject to a lot of natural variability, so the premise that changes should be ‘monotonic’ – temperatures rising in straight lines – ignores the fact that nature doesn’t work like that. This is why scientists normally discuss trends – 30 years or more – so that short term fluctuations can be seen as part of a greater pattern. (Other well-known cyclic phenomena like El Nino and La Nina play a part in these complex interactions).

Looking at the trend in ocean heat, this is what we find:

Source: Levitus 2009

There are, however, disputes about the accuracy of Argo buoys and expendable measuring devices dropped into the sea, and the reporting of temperatures down to only 700 metres. How do scientists resolve these kind of disputes – bearing in mind that such disputes are the very stuff of science, the essence of true scepticism? One way is to find more data sources – different ways of measuring the phenomenon in dispute. By using results from seven different teams of scientists, all using different tools and methods, we are able to see a clear trend. And while there is variation between team results due to the differences in technique and measurement methods, one thing they all agree on: long term, temperatures are going up.

Source: Lyman 2010

The reaction of the oceans to climate change are some of the most profound across the entire environment, including disruption of the ocean food chain through chemical changes caused by CO2, the ability of the sea to absorb CO2 being limited by temperature increases, (and the potential to expel sequestered CO2 back into the atmosphere as the water gets hotter), sea-level rise due to thermal expansion, and the amount of water vapour in the atmosphere.

While there is a great deal we don’t know about how the oceans behave, we do however know that it’s safer to discuss all aspects of climate change using multiple sets of data, rather than just one, as Pielke Sr did. If ocean heat is a guide, then global warming is still on track to cause great disruption if we don’t modify our actions to reduce the release of anthropogenic CO2.

Claims that global warming is not happening on the basis of short-term ocean temperatures are not supported by the evidence.

2010-08-25 18:12:26Bump
Graham Wayne
I'll just vote for myself then...
2010-08-27 05:37:29Looks good to me!

In the second last line there's a full stop after the abbreviation Sr, but as the abbreviation ends in the same letter as the original word it should not be there. 
2010-08-27 07:00:44


nice piece Graham, well done. I do have some suggestions.

In the third paragraph, you could cut out " It’s an important question then, seen in context", and the message is still clear.

The entire fourth paragraph could either be cut or moved to the end. It's all true, yes, but it's not about if the oceans are cooling or not. It's about why it's important that they're not. So I don't think it belongs in the main flow of the argument.

Where you have "We only ‘appear’ to find this irregular, but clearly upward trend, because there are disputes about the accuracy of Argo buoys and expendable measuring devices dropped into the sea, and the reporting of temperatures down to only 700 metres...", I think that could benefit from rephrasing. It doesn't read too easily, I had to go through it two or three times and I confess I'm still not too sure what the point is. There is a clear trend, so I think you should state this first. If you want to say that the irregularity is the subject of debate, you should make that as a second point.

Similarly, later on, I would rephrase the part that says "we are able to see a clear trend – albeit with considerable variation between team results, but one thing they all agree on. Long term, temperatures are going up." Make the statement about the trend a short sentence on its own, to give it more impact. Something like: "we are able to see a clear trend of rising temperature. There is considerable variation between the results of different teams, which is a consequence of using different measuring techniques. However, one thing they all agree on, temperatures are going up.

I also think the impact of the first paragraph could be improved. By quoting Pielke in the way you do I feel you draw more attention to him than to the argument at hand. I may be splitting hairs here, but I think people may come away remembering him and what he said more than the rest of the argument, especially if they only skim the article. Here's a possible change to the opening:

Some sceptics (e.g. Pielke) claim that the upper ocean hasn't been warming since 2004, and that this disproves global warming. This claim is based on two fallacies.

The first fallacy is that ...(lung cancer analogy)

The second fallacy...

I hope I'm not being too harsh, you've done a great job here.

2010-08-27 18:07:06Responses
Graham Wayne

Niamhaill: An arcane point there, but I'm happy to comply...(had no idea)

Tony: really good points, not harsh at all. I've addressed them all except the opening. My own view is that by deconstructing Pielke Sr I add a little of my own work in exposing method. It is also consistent with the intermediate version, which also opens with the same remarks. Anyway, thanks a lot for spot on (constructive) criticisms - hope you feel I have addressed them responsively.

2010-08-28 05:52:24

I confess I haven't read the intermediate version, I agree being in line with it makes sense. I think this is fine as it stands now, you get the thumbs-up from me.
2010-08-28 10:10:56


I like the thematically consistent "use all the data" tone of this. 

I'm thinking behavior of ocean temperature readings described as "chaotic" and "non-linear" would more accurately be characterized by "natural variability."

2010-08-28 16:50:13Chaos or not?
Graham Wayne
OK Doug - less jargon is good so natural variability it is!
2010-08-28 16:53:47

Vote early, vote often!
2010-08-28 17:40:29suggestion



 I don't care for the term "arch-skeptic", as we've discussed before. In particular, you are attacking RPs, who is not only an active researcher, but also participates actively in the climate blogosphere.

I am not a respecter of persons, but I suggest:

- Finding a more diplomatic way of describing his stance. (To be honest, I do not completely understand his point of view. He seems to be technically very competent on specific issues; I'm not clear on why he always leans towards the dismissive side.)

- Get someone who really qualifies as a climatology expert to vet this posting. As someone once said, "When you shoot at a king, you must kill him."


2010-08-29 16:26:06Response to Neal
Graham Wayne
I just changed it to 'sceptic' Neal - think that's quite fair and appropriate. Not sure why we would need additional expertise since all I'm really saying is 'don't make assumptions based on one data set alone, else you may come a cropper"...which he did.
2010-08-29 19:49:24why?


Just for insurance: RP senior is a bonafide expert, so if you're gonna say he's not wearing any pants, you want to be sure you're right.

 Maybe John Cook can tap an expert for this, as a favor.



2010-08-30 17:40:47Bump


Lyman's group of experts concentrated in the specific domain of oceanography far outweigh Pielke's less relevant expertise. Lyman and his coauthors are exactly the kind of experts of which Neal is thinking.

Money shot from Lyman et al:

Accounting for multiple sources of uncertainty, a composite of several OHCA curves using different XBT bias corrections still yields a statistically significant linear warming trend for 1993–2008 of 0.64Wm-2 (calculated for the Earth’s entire surface area), with a 90-per-cent confidence interval of 0.53–0.75Wm-2.

That's from the Nature abstract in 2010, as opposed to Pielke's blog remark in 2008.

Graham, perhaps you should emphasize how Pielke stands as an outnumbered, outgunned, superseded outsider on this.


2010-08-30 21:55:06

looks good to me - well done
2010-08-31 02:16:26Has the skeptic claim been answered directly?
Jim Meador


The skeptic statement is that oceans have not warmed since 2004.

The basic message of this rebuttal so far is "Yeah, but there was a lot of warming before that. Six years is not a significant stretch of time." Then there is a lot of information about the accuracy of the measurements, even though the statement of the skeptic argument does not question the accuracy of the records.

So this rebuttal does not directly address the skeptic claim.

I think this rebuttal should be shortened down to focus on the key issue: Warming since 2004 has indeed been flat. Provide some basis by which this is not so surprising ...normal variability in ocean temps given various forcings. (In particular it seems to me that the solar forcing has been relatively low of late, but I don't know if there is any publication to reference that this has affected recent ocean temps.)

2010-08-31 02:50:35

Forgot to mention, emphysema might be a better disease to refer to w/regard to shortness of breath.
2010-08-31 06:01:38Second Jim Meador
Nicholas Berini


I think this specific sceptic argument can be addressed in simpler terms along the lines of "global warming stopped in 1998."  

"The fact is that climate data is best analyzed over decade-long (or longer) periods, and every data set on the subject indicates a clear warming trend." 

 You very adequately address a question of "is ocean heat data flawed?"  I think using the Lyman data and explaining how what we're looking at is the long term trend adequately addresses both questions. 

2010-08-31 14:17:1180%?
Dana Nuccitelli


Is it true that the oceans store approximately 80% of all the energy in the Earth’s climate?  I thought it was over 90%, no?

I'd add something about the long-term trend and how focusing on just a few years of data confuses short-term noise with long-term signal.  Just a couple of sentences would suffice.  Otherwise it looks good.


2010-08-31 16:43:31No changes
Graham Wayne

Sorry folks, but there seems to be some nit-picking going on to which I can't really respond. Neal seems to think Lyman 2010 isn't expert enough. RP may be prominent, but that doesn't speak to credibility, which would be rather more substantial if he hadn't cherry picked a data set to make his case.

Doug - I don't want to indulge in overkill either. I've said very clearly that using all the data is prudent, and explained why. Further criticism looks like character assassination.

Jim says "Warming since 2004 has indeed been flat." That isn't what Lyman says, as Doug points out, and I disagree that the rebuttal doesn't address the argument. You have misrepresented what I written, for I have not said or implied that "Yeah, but there was a lot of warming before that..." I've said that science finds the temperatures have continued to rise, again - confirmed by Lyman.

Dana - I know what you mean, but like Nicholas' suggestion, it's very easy to chuck in half a dozen other denialist memes, but the rebuttals end up confused and too long. We address long term trends v weather in other rebuttals, as we do noise v signal etc.

Can I just add that what I have written is wholly consistent with the intermediate version. I will not attempt novelty, add new information or re-contexualise what JC has done previously, because I'm not expert enough to do so, and because discrepencies between basic and intermediate versions makes us look a bit silly.

2010-09-01 04:14:01More focus on the recent trend
Jim Meador


Hi GP,

Yes, the Loehles argument is focused on 2004-present, and finds a downward ocean temp trend, as you say. So I would like to see part of the rebuttal focused on that period. (Although it is certainly also valid to claim that the period was cherry-picked.)

The Lyman figure does show pretty flat temps from 2004 on (to my eye) and there is no trend line to compare to Loehles. Doug points out that Lyman shows a trend for 1993-2008, which again misses the period mentioned by the skeptics.

I am just saying that the rebuttal should directly address the claims of the skeptic, and in my reading of the rebuttal above I feel like it misses the mark. Nothing I am seeing effectively counters the power of the figure from Loehles for the period of interest:


Figure 1: Heat content smoothed with 1-2-1 filter and overlaid with linear trend portion of best-fit model (slope = -0.35 x 1022 J/yr) 

2010-09-01 21:06:03Response
Graham Wayne
OK Jim - I take your point - sorry if I was a bit slow on the uptake. I've amended the opening paragraphs as well as the ending, to focus more on the specifics of the argument. See what you think...
2010-09-02 09:33:58with all due respect



The issue is not whether Lyman is expert enough, the issue is whether YOU are expert enough, as YOU are putting the article together.

 (And if I were putting the article together, I would have equal doubt about my own qualification.)

You are writing an article that is calling Roger Pielke Sr. (not Roger Pielke Jr., and not Steve McIntyre; RPs is a bonafide researcher in the field, and even the RealClimate folks are quite careful about him, even when they disagree) an idiot. You better make damn sure you are right, or you will damage the "brand" that Skeptical Science has achieved for fairness.







2010-09-02 10:07:29I'll give this one a thumb now...
Jim Meador

Good work GP!
2010-09-02 12:51:15
Michael Searcy


Great job, Graham, and a sixth thumb from me.

A couple of minor nits....

  1. "Claims that global warming has stopped is not."  Change "is" to "are"
  2. Can the source references for the graphs be changed to links?
2010-09-02 23:57:06Nits - picked!
Graham Wayne
Thanks Michael - done and done...
2010-09-04 00:34:59Not happy with this rebuttal
James Wight

Sorry, Graham, but I’m not really happy with this one either. Not your fault, though – this is a difficult argument to rebut because there is some truth to it.

Of course, I’m no expert either – and I’m not entirely sure that I fully understand the OHC issue myself – but I’d try to emphasise the following points:
•    Yes, ocean heat content is only one indicator but it is a pretty fundamental one considering something like 90% of global warming is going into the oceans.
•    However, our ocean observing systems are not very good, and have changed a lot over the last few years so that may explain some of the discontinuity.
•    Also, measurements of OHC down to two kilometers find that since 2003 the oceans have accumulated heat at a rate of 0.77 W/m^2 (which I think works out to 0.54 W/m^2 globally.)

Ideally we would have an expert look over it but unfortunately we’re not likely to have that luxury!
2010-09-06 18:37:33Published
John Cook


You know, my intermediate rebuttal needs some refreshing - it needs the latest from von Schuckmann of ocean heat down to 2000 metres.

Sigh, so much science, so few hours in the day...