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Oceans are unprecedentedly alkaline

Mollie seemed more sensitive to acid waters than her friendsRuth Dixon has an interesting blog post on ocean acidification and in particular Fiona Harvey's claim that oceans are "more acidic now than they have been for at least 300m years". Following the claim to its source reveals that the truth has been lost in translation.

Hönisch et al. 2012, cited by the State of the Oceans report, showed in Figure 4D that

the ocean has been more acidic for most of the past 300 million years than it is now. The rate of acidfication may be faster now, but Hönisch’s graph has a resolution of 20 million years, so cannot address that question.

It is unfortunate that an environmental journalist should confuse the rate of acidification with levels of acidity, but appalling that this story was tweeted uncritically by Nature Geoscience and other influential accounts. This is not some esoteric area of climate science. It is well known that CO2 was much higher during parts of the past 300 million years than it is today and therefore ocean surface pH would be expected to be lower. Why was Harvey’s assertion that “[the] oceans are more acidic now than they have been for at least 300m years” not challenged (as far as I can see) by anyone from the scientific establishment?


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Reader Comments (39)

Why was Harvey’s assertion ... not challenged (as far as I can see) by anyone from the scientific establishment?

She was choosing to be effective, rather than honest.

Misleading and untruthful reportage is acceptable as long as it serves the ecofascists' noble cause.

Oct 7, 2013 at 1:30 PM | Unregistered CommenterJustice4Rinka

In the film "Alien Nation" with James Caan, the aliens couldn't go near the sea because its effect was "like battery acid" to them.

Ms Harvey is probably just showing concern for any future extra-terrestrials who might be visiting.

Assuming that is, they can get the Guardian website down Alpha Centauri way.

Oct 7, 2013 at 1:54 PM | Unregistered CommenterJohn Barrett

The assertion that Fiona Harvey is a 'journalist' is not supported by the evidence at any confidence level.

Oct 7, 2013 at 2:06 PM | Unregistered CommenterRick Bradford


Indeed. Activist-reporter perhaps. "Journalist" implies that a degree of scepticism and scrutiny have been applied. There is no evidence of either in Ms Harvey's emissions.

Oct 7, 2013 at 2:13 PM | Unregistered CommenterJustice4Rinka

Perhaps she doesn't know her eons from her ions.

Oct 7, 2013 at 2:15 PM | Registered CommenterPharos

There are more biochemists than radiative physicists.

Many of them conduct experiments in incubators where the level of CO2 is artificially raised to 4% concentration. I think most of them are going to take a lot of persuading that hypothesised future atmospheric CO2 changes are any significant problem regarding oceanic pH as effected by CO2; pH levels which are not even close to being as acidic as pure water itself.

Carbon-based life forms have many hundreds of millions of years experience both creating, and dissipating, far higher levels of carbon dioxide.

Oct 7, 2013 at 2:20 PM | Unregistered Commentermichael hart

So what is it with these warmists that they want the oceans to be more caustic. Is it in their character.

Oct 7, 2013 at 2:39 PM | Unregistered CommenterPeter Whale

Excellent work. Another illustration of how 'just taking a look' can undermine overblown claims from over-zealous campaigners.

Oct 7, 2013 at 2:53 PM | Registered CommenterJohn Shade

A welcome tweeted apology from Nature on the update to Ruth Dixon's blog.

'Nature Geoscience @NatureGeosci

Tracing a problematic interpretation across the internet … Also, oops for our role in its propogation via @ruth_dixon
1:14 PM - 7 Oct 2013'

Even more impressive if they could spell propagation.

Oct 7, 2013 at 3:18 PM | Registered CommenterPharos

The same reason they put the myth of the gulf stream shift into the IPCC report - because these clods don't even know their own subject, nor can they ever be bothered to verify anything by actually doing some reading. Why should they when they are always treated as omniscient by science journalists anyway - even when their fairy stories contradict one another?

Oct 7, 2013 at 3:37 PM | Unregistered CommenterJamesG

Because most journalists have no scientific training?
They have ceased to be effective, i.e. enquiring, journalists?
Most climate psientists are activists and crooks?

All of the above?

Oct 7, 2013 at 3:42 PM | Unregistered CommenterDon Keiller

If only it were the "journalists" .... Trouble is .... ocean acidification has developed into a whole academic activist carnival and Fiona is simply a single maraca shaker.

I saw Fionas ghastly GMG article and dropped a comment in unthrreaded - but - I was a bit uncomfortable that I'd missed something so I went looking again - and found some enormous, expensively decorated and brightly lit carnival floats blasting out the music of doom and manned by the crew of the UK's flagship marine science establishments ...

The graph on page 2 of this POS makes the hockey stick look tame

I can't actually do justice to - it's simply amazing.- and I do not mean that in a positive way.

Oct 7, 2013 at 4:05 PM | Registered Commentertomo

Don Keiller, I think the word you're looking for is desperate. They're desperate for something, anything, to prove that CO2 is as scary as they've made out. In their excitement at having found something they don't ask questions (ok that could apply to both sides but the onus of accuracy is on their side).

How long before this claim is regularly used by people like Ed Davey to demonstrate how things are worse than predicted? Ocean acidification is the new black.

Oct 7, 2013 at 4:10 PM | Unregistered CommenterTinyCO2

BTW, Your Reverence, kudos for the photo caption. Once the alarmism thing has gone away, you might look into working for those greetings card chappies.

Oct 7, 2013 at 4:43 PM | Unregistered CommenterJames Evans

- THIS MEGA cos it sums the entire climate debate in a simple in a microcosm :A brilliant example of fearful alarmists vs Skeptics
- I realise the difference of thinking : they are coming from a base of FEAR.... fear drives "drama queening panic", drives rush, drives getting facts 180 degrees confused
- Greendream followers have no feeling for science & are sloppy with it and also in a rush retweet (& ALMOST NEVER CORRECT later).
Who shows these colors ? The Guardian made an fundamental error in the first sentence & neither their professional editors or fanboys spotted it... Fiona Harvey ran to plug her story by tweeting that first sentence.. then retweeted by @NatureGeosci, @BBCNewshour, @bbcworldservice, @GeorgeMonbiot (followers retweeted 101 times)
- The Guardian page gathered 371 comments, before comments were switched off ..non of the uncensored comments mention the error ..they just all ploughed in "fault of big oil" etc. etc.

- It's like in the famous experiment, where people miss the obvious gorilla. Focused on the fear they just don't see the same big picture, that skeptics do.
- How come they didn't spot the error at the 5th word ?
"The oceans are more acidic" hmm "The Oceans are BECOMING more acidic AT A RATE" or "oceans acidification is more" is what they meant to say
- But their thinking is "What's wrong with that ? Doh, we are all going to die, you fool ! that's what's wrong !"

- And we can trust the "consensus scientists" cos they stepped forward to correct the public record ? Oh seems like a "no", cos after 4 days none have.
- Also note how media and politicians are quick to republish greendream stuff from scientists speaking outside their field, instead of going to an experts.

- How can that "tiny minority" geeky old skeptics be right and all the AFEARED : the cool artistic crowd, the authorative Guardian and BBC be wrong ?'s not possible !

Oct 7, 2013 at 5:05 PM | Registered Commenterstewgreen

BTW was it NEWS anyway ?
the headline in Washington Post 31st Aug & Time on 2nd March "Sea Changes: Ocean Acidification Is Worse Than It’s Been for 300 Million Years and same mis extrapolation then
e.g. @s_guilbeault 2 Mar 12
"Our oceans now more acid than they've been for 300 MILLION years because of increasing CO2 levels "

- Steve Burnett wrote a good item in WUWT in July

Yes credit to @NatureGeosci (took them 4 days to correct tweet)

- The Alarmist PR machine gets every climate story MEMED with the usual polar bear photo, can we meme each counter-commentary with a pic of a drama queen ?

Oct 7, 2013 at 5:09 PM | Registered Commenterstewgreen

Warmistas don't seem to understand basic ocean chemistry.
The oceans are essentially a buffer solution. If anything, adding more CO2 (to form carbonic acid) tends to slightly increase alkalinity. Reason being that H2CO3 chemically attacks insoluble limestone, suspended CaCO3 and shell sludges, corals etc to form Ca(HCO3)2 - Calcium bicarbonate. This is both soluble and alkaline.

Also, as there is liquid CO2 in ocean trenches, the oceans are more or less saturated in CO2 anyway.

Oct 7, 2013 at 5:20 PM | Unregistered CommenterPhilip Foster

I liked the caption accompanying the photo above (it reminded me of Glen Baxter).

Mollie seemed more sensitive to acid waters than her friends

Oct 7, 2013 at 7:08 PM | Unregistered Commenterharold

Ruth Dixon

I trust something suitable has been procured from the Oxford College cellars.


Oct 7, 2013 at 7:09 PM | Registered CommenterPharos

Thank you, Bishop (and others!) for linking to my post (it’s made it my ‘most-viewed’ post ever! :-)). Thanks, Pharos ... I wish... we had a glass of Rioja tonight.

The graph that Tomo linked to at 4.05pm is interesting. I’ve seen a version of it before, in a presentation from the UK’s Department of the Environment, Food and Rural Affairs (DEFRA) written by Dr Carol Turley (lead author on AR4).

Slide 3 shows the graph and cites Pearson and Palmer's data for past pH values (the Nature paper from 2000 that I linked in my post). However, it shows only their data from 25 million years ago and not their whole timescale back to 60 million years (and so omits earlier, more acidic, pH values). It then splices (TM) the future predictions on to that dataset - which of course have a far higher time resolution - Pearson and Palmer have only about one data-point per million years.

Slide 3 says “By 2050 the pH range will be discrete from the pre-industrial pH range. We will be in unknown territory”… but this is only because the author decided not to include that ‘territory’ on the graph.

Oct 7, 2013 at 7:51 PM | Registered CommenterRuth Dixon

Tomo (Oct 7, 2013 at 4:05 PM):

Wooh! See what you mean. From how it appears to me, the rate of acidification is truly terrifying – from pH8.25 3 million years ago to pH8.1 now! At that rate, it will only be 21 million years before the oceans are neutral! How will we cope? (That it has never been lower than pH8.0 in 23 million years is irrelevant, of course; that it will never reach pH7 is also irrelevant, as we must DO SOMETHING ABOUT IT!)

Oct 7, 2013 at 10:06 PM | Unregistered CommenterRadical Rodent

'Why was Harvey’s assertion that “[the] oceans are more acidic now than they have been for at least 300m years” not challenged (as far as I can see) by anyone from the scientific establishment?'

To be fair she was just following her normal practice , straight reproduction of green PR without thought nor investigation as befits a human photocopying machine.
While the scientific establishment has spent, at best , the last few years playing the 'three wise monkeys ' over climate doom . Its been one of the sadist elements of this whole thing that those that should have acted as gatekeepers of scientific integrate have failed so badly in this task over climate 'science' An issue we may all pay the price for.

Oct 7, 2013 at 10:30 PM | Unregistered CommenterKNR

More "Churnalism" from the PPE graduate, Camilla Cavendish

I dont give anyone a free pass. Im not a scientist and will always be limited by that but Ive studied this issue for years and talked to many scientists about it. Im afraid I cant agree with you that the ipcc is a "pressure group". Sorry.

On 6 Oct 2013 17:03, "Don & Selina" <> wrote:

Dear Ms. Cavendish, many thanks for your prompt reply. Whilst you are correct in saying that there “has not been a similar hiatus in ocean temperatures”, this paper
“World Ocean Heat Content and Thermosteric Sea Level Change (0–2000 m), 1955–2010)” by Leviticus et al (2012)*, report conclusively demonstrates that any warming that has occurred at the very limit of measurability and is most likely not significant.

Here is the abstract:

We provide updated estimates of the change of ocean heat content and the thermosteric component of sea level change of the 0–700 and 0–2000 m layers of the World Ocean for 1955–2010.

Our estimates are based on historical data not previously available, additional modern data, and bathythermograph data corrected for instrumental biases.

We have also used Argo data corrected by the Argo DAC if available and used uncorrected Argo data if no corrections were available at the time we downloaded the Argo data.

The heat content of the World Ocean for the 0–2000 m layer increased by 24.0 ± 1.9 × 1022 J (±2S.E.) corresponding to a rate of 0.39 W m−2 (per unit area of the World Ocean) and a volume mean warming of 0.09°C.

That last number (0.09 degrees) is the “money shot”. What they are saying is that in the last 55 years the oceans have warmed by less than one tenth of 1 degree. Put like this it is not very scary is it?

So once again- I ask you to think very carefully about the information you have been provided with.
Just because it is “climate change” and all about “saving the planet”, should not give breathless headlines from the IPCC and other pressure groups a “free pass”, rather they should be subject to the same objective scrutiny as any other story.


Dr. Don Keiller.

Oct 7, 2013 at 11:11 PM | Unregistered CommenterDon Keiller

These extreme overstatements that warmists so often make ..are they genuine mistakes ? or exaggeration lies to make their case stronger ?
- why would anyone feel the need to keep going beyond the truth ?
... Hang-on I am channeling Sir Bob Geldof
..sorry 4language, his passion carries him away sometimes

Of Of course they're freakin lies !
for freaks sake,
the whole life of the freakin planet is at stake !
We need your lies !
send us your freakin lies ...NOW !

.. please make his new single "Do they know it's BS ?" the Xmas #1

Oct 7, 2013 at 11:46 PM | Registered Commenterstewgreen

1. Surface sea water is super saturated with calcite, aragonite and dolomite ( forms of calcium and magnesium carbonate.
2. Precipitation of inorganic CaCO3 occurs in few sub and tropical areas.
3.Below the carbon conception depth , the pressure is so high that the amount of dissolved carbon dioxide is so high that no calcium carbonate can be precipitated .
4.For the seas to be acidified all the CaCO3 both in solution and as a precipitate would have to be used up.
5. Any increased in temperature would reduced CO2 content ( solubility of gases are inversely proportional to temperature and proportional to pressure), for them to be acidified would mean that all the excess CO3 would have to be used.Increase in temperature and CO2 would increase photosynthesis by phytoplankton..
6. CO2 reacts with H2O to produce H2CO2 carbonic acid.
6. CaCO3 + H2CO3 <>Ca2+ + 2HCO3-
7. Ca2+ comes from Feldpsars washed by rivers. .
8. Sea water is very well buffered against increase in acidity or alkalinity.

Oct 8, 2013 at 12:29 AM | Unregistered CommenterCharlie

Ruth / RR

Whooh! indeed Ruth thanks for the provenance of that graph ...

Looking at the website of looking for "how does that work then?" sort of information seems to throw extraordinary quantities of ecoBS up for what is supposed to be a science portal.

I was expecting science but find almost wall to wall expensively photographed raggedy - arsed sad kids and fisherman on Guardianista fantasy tropical beaches. Puff pieces for people looking for funding for researching the effects of something that they aren't actually prepared to provide evidence for actually happening.

it's just toecurling - nobody's even broken rank to propose something so silly that it's a spoof - I can't believe the craven politic-ing of the marine scientists - just appalling.

Oct 8, 2013 at 1:31 AM | Registered Commentertomo

300M years takes us back to the Permian .

During this period has been the Jurassic which produced vast volumes of limestone and the Upper Cretaceous which produced the Chalk.The mid Cretaceous had up to 5x the amount of CO2 in the atmosphere. During much of the Jurassic much of the atmosphere contained 3x the amount of the present day CO2.

Much of the limestone in the Middle East/Med was deposited in the last 50M years.

For seas to precipitate CaCO3 they must be super saturated with the compound. Rain water, producing carbonic acid falls on Feldspars containing calcium. Calcium ions enter the seas via rivers and react with HCO3- to produce CaCO3.

Basic chemical sedimentology no longer appears to be understood.

Oct 8, 2013 at 10:19 AM | Unregistered CommenterCharlie

It's the book of Jonah brought up to date:
'The IPCC began by going a day’s journey into the city, proclaiming, “Forty more years and civilisation will be overthrown.” The people believed the IPCC. A fast was proclaimed, and all of them, from the greatest to the least, put on sackcloth.'
What we need is more sackcloth (possibly).

Oct 8, 2013 at 10:48 AM | Unregistered Commenterosseo

If you seek to do a correct investigation of matters like the pH of oceans, it helps to start with the correct definitions.
pH is defined as the negative logarithm to base 10 of the hydrogen ion activity.
I do not recall this definition being used in ANY climate literature.
Typically, 'activity' is replaced by 'concentration'. This is an approximation that converges for very dilute solutions. Ocean waters are NOT very dilute solutions.
Activity is related to concentration via a dimensionless number, the activity coefficient.
The activity coefficient, in turn, is dependent on the total ionic strength of the solution, being described in one way through the Debye-Hückel equation shown here from Wikipedia -
If you follow this link, you will see some of the complexity that is glossed over in your average, poor quality climate paper.
Such papers will give the wrong answer, when the right way to the answer has been known for many decades. D-H was first published in the early 1920s. It a more appropriate appropriate method for treating pH of ocean water.
pH cannot be measured accurately by dipping a conventional pH electrode into the water - or rather, it can, provided that certain known effects are used to correct the raw readings. This is because of the influence of other inorganic species such as calcium ion; plus suspended species, which make electrode readings unpredictable; plus the presence of biota, which can be expected to have effects (such as excretion of acid or alkaline products and other effects beyond those known to me in detail). Rather than measure pH directly, resort is often made the equilibrium diagrams, such as the Bjeerum plot. One can calculate ocean pCO2 and pH from DIC, alkalinity, and temperature. However, such calculation depends critically on the accuracy of the stability constants used to generate the plot.
(The URL above gives yet another paper that mistakes concentration for activity. It also notes that CO2 in the air, reacting with seawater, does not behave as an ideal gas. A purist would correct this discrepancy.) Then there are problems with how much CO2 dissolves in oceans as opposed to pure water, the Revelle factor, etc. - see
Then there is non-ideal gas behaviour of CO2 going into sea water, which requires correction.
Then there is the sea water dissolution of carbonate rocks, where calcite and dolomite behave differently, so affecting calcium content of water.
Even mixing has to come into it, because the deeper oceans are much less alkaline than the surface skin.
There is good reason to believe that a great deal of past climate related work on the ocean pH as affected by CO2 is simply wrong. It might not be wrong by much, but these guys are chasing changes of 0.1 pH in 25 years, that sort of difficult dream.
p.s. I'm doing this from memory, last visited for a Masters' thesis around 1969, so E&OE.

Oct 8, 2013 at 11:34 AM | Unregistered CommenterGeoff Sherrington

The unlamented Tim Flannery was apparently convinced that CO2 produced CARBOLIC acid in sea water.
This is from an "interview" with Flannery, at a Tata conference.

'Climate change is a threat to our civilisation'
Q. What are the immediate steps that need to be taken to combat climate change?

A. The first step is to stop producing so many polluting carbon emissions.

Q. Many cynics believe that climate change and global warming are theories put forth by alarmists without any scientific basis. Why do you think there is worldwide denial even when the effects are plain to the eye?

A. Sometimes the issue of climate change does seem overwhelming and there are fears about acknowledging climate change and what it means. It means that we are responsible for changing conditions on the surface of the earth. However, much of the science is self-evident. One example is the issue of coral reefs. In Australia we have conducted a series of experiments where we have taken sea water, reduced its acidity and temperature to create conditions as they were 200 years ago and then put coral in that; the coral thrives in that water. We can take sea water as it is today and coral does not grow so well. We can put coral into water with conditions as they will be in 10 years’ time and we will see that the coral is stunted and dying. We can see that this will happen — carbon dioxide in the atmosphere produces carbolic acid in the ocean, the ocean becomes acidic and things die.

Was it a typo? Well, he had also said it in his 2009 book, "Now or Never: Why We Need to Act Now to Achieve a Sustainable Future. It was picked up by a reviewer at the time,, but he was still repeating the error in January this year at the Tata Conference. Other green reviewers have quoted it verbatim, the ignorance is appalling.

It has also been quoted by his friends in Europe,
The EU FP7 Integrated Project EPOCA (European Project on OCean Acidification) was launched in June 2008 with the overall goal to advance our understanding of the biological, ecological, biogeochemical, and societal implications of ocean acidification. The EPOCA consortium brings together more than 100 researchers from 27 institutes and 10 European countries.

There is a blog linked directly to the project site:
This blog was started in July 2006 as a “one man” effort. It is a product of EPOCA, the European Project on Ocean Acidification since May 2008 and it is sponsored by the IMBER and SOLAS projects since January 2010.

This blog is coordinated by:

Jean-Pierre Gattuso, CNRS Senior Research Scientist, CNRS-Université Pierre et Marie Curie Paris 6, France

AR5: The list of authors and review editors of IPCC Working Group II, 5th Assessment Report, includes Jean-Pierre Gattuso from EPOCA.

If this blog is co-ordinated by Gattuso, a lead author on AR5 WGII, you would assume he would read what is written there.

“Too much carbon is flooding the ocean with carbolic acid, with devestating (sic) effects on life in the sea.” (no wonder!)

They have other contributions, such as this one from the Australian Academy of Science:
“Chemists have known for a long time that a beaker of water sitting in a lab will absorb carbon dioxide from the air and turn acidic. Would it happen at a larger scale? If we greatly increased the concentration of carbon dioxide in the world’s atmosphere, for example, would the oceans become a vast acid bath? What would be the ecological effects? Over the next century or so, we are going to find out.”

Oct 8, 2013 at 12:05 PM | Registered Commenterdennisa

The only thing demonstrating an unprecedentedly high level of acidity is the bullshit peddled by eco-advocacy shills and carpetbaggers.

Oct 8, 2013 at 2:09 PM | Unregistered Commenterpleading the fifth

"The Guardian page gathered 371 comments, before comments were switched off ..non of the uncensored comments mention the error ..they just all ploughed in "fault of big oil" etc. etc."

That's not quite fair. Try checking the various comments of "Paul_K2". They did allow me these responses:-

The IPSO talks about both rate and level. Here is the money quote (from source)
"Today’s rate of carbon release, at approximately 30 Gt of CO2 per year, is at least 10 times faster than that which preceded the last major species extinction (the Paleocene Eocene Thermal Maximum extinction, or PETM, ca. 55 million years ago), while geological records indicate that the current acidification is unparalleled in at least the last 300 million years."
The second statement is complete balderdash, while the first statement is speculative and probably wrong. There have been some studies to try to estimate carbon release during the PETM, but none of them would get anywhere close to a factor of 10 on comparative emission rates.

and this

Interesting definition. Atmospheric CO2 was around 2000 ppm during the Jurassic. Henry's Law on solubility of CO2 plus what we know about equilibration between carbonic acid, bicarbonate and carbonate from physical chemistry tells us that the oceans at that time were far more acid than now. This is not a fact that is in any dispute in scientific circles. So pick your own noun - balderdash, nonsense or crap all work OK.

Oct 8, 2013 at 5:19 PM | Unregistered CommenterPaul_K

I do not see how seas can have pH below 8.1 as they are so well buffered . Increased CO2 will also cause phytoplankton blooms which when they die will transfer carbon to the sea floor and produce the source material for oil. Most source material for oil was produced during warmer periods with higher CO2 levels in the atmosphere.

Oct 8, 2013 at 6:34 PM | Unregistered CommenterCharlie

@Paul_K No the 371 comments did not mention the simple obvious error *
- The error was writing "The oceans are more acidic" when they meant "The Oceans are BECOMING more acidic AT A RATE"
ie the confused the VALUE which NOT even the report says is higher than ever
with the RATE of CHANGE which the report DOES claim is extraordinary

* I checked using C-trl F & "more acidic" ..I cannot rule out that it did crop up buried in one of the sub-comments

Oct 8, 2013 at 10:19 PM | Registered Commenterstewgreen

Well I won't get into a big argument about it, but I think that the original IPSO report was ambiguous at least.
In terms of the Guardian moderation policy, they did allow me in a separate article to take apart Fiona Harvey's less ambiguous statement.

Paul_K2 commented on Global warming sceptics using media campaign to discredit IPCC.07 Oct 2013 10:08am 8
Instead of accusing me of distortion, it might be easier if you were to verify some facts for yourself.

The statement which appeared in Fiona Harvey’s report of the IPSO was

The oceans are more acidic now than they have been for at least 300m years, due to carbon dioxide emissions from burning fossil fuels, and a mass extinction of key species may already be almost inevitable as a result, leading marine scientists warned on Thursday.

The source of this, the IPSO report, unambiguously referred to 300 million years, which period includes inter alia the Triassic, Jurassic and Cretaceous. It is not in any way controversial that atmospheric CO2 levels during the Triassic/ Jurassic were about 5 times higher than today; CO2 levels of greater than 3 times higher than today were apparent throughout the Cretaceous. See studies here for example .
Unless someone has decided to rewrite geological history or to reject well established rules of physical chemistry, the oceans had a far lower pH during all of that time than they do today. The statement then is, as I said, contrary to all the scientific evidence. It is not even a controversial issue.
With respect to Figure 1.4 of the recent IPCC report, you can verify for yourself readily enough that this graph was produced by some still-anonymous IPCC authors. It was not drawn from peer reviewed literature. Material which is drawn from the literature is cross-referenced in the IPCC report. This was not, and nor was it included in the second order draft which went to reviewers. As to whether it can be replicated, it was produced using a methodology quite different from those used in the first four reports; unfortunately, that methodology is not fully specified, particularly with respect to baselining; nor does its description include the criteria for the selection of samples from the CMIP datasets which went into the spaghetti part of the graph. However, I am happy to be proved wrong on this – all you have to do is to show me how to replicate the graph or refer me to someone who has done so.
With respect to its validity, my main point is that the graph was purpose-designed to give the impression that the GCMs are still broadly compatible with observational data. The text of the WG1 report however rather more meaningfully notes
However, an analysis of the full suite of CMIP5 historical simulations (augmented for the period 2006–2012 by RCP4.5 simulations, Section 9.3.2) reveals that 111 out of 114 realisations show a GMST trend over 1998–2012 that is higher than the entire HadCRUT4 trend ensemble (Box 9.2 Figure 1a; CMIP5 ensemble-mean trend is 0.21 ºC per decade).

Two recent papers - too late for inclusion in the IPCC report - confirm a significant divergence of temperature trends between models and reality since the turn of the century.
Spin and distortion is by no means restricted to the Heartland Institute and the GWPF.

Oct 9, 2013 at 9:43 AM | Unregistered CommenterPaul_K

Thanks Paul_K, for drawing attention to your comments and I've added links to them in the comments below my post (and updated my post). I did not notice them when I looked through the comment stream below the original article. The comments were closed by the time I read the article. I am glad that you and others questioned this assertion in the comments on the article itself.

Oct 9, 2013 at 12:21 PM | Registered CommenterRuth Dixon

I hope you'll be pleased to hear that the headline and first paragraph of the article have now been changed following email correspondence between Fiona Harvey and me. Credit to Fiona and the Guardian for this response. The links in my post now lead to the updated version which can be compared with the screenshot given there.

And no, I wasn't credited!

Questions remain about the role of the authors in allowing this misinterpretation of their report to stand. The lead author and founder of IPSO tweeted the article approvingly on 3 October

Oct 9, 2013 at 1:14 PM | Registered CommenterRuth Dixon

Ruth Dixon,
Thanks for the acknowledgment - unnecessary but very courteous.

Oct 9, 2013 at 7:16 PM | Unregistered CommenterPaul_K

Ruth Dixon- 'Questions remain about the role of the authors in allowing this misinterpretation of their report to stand. The lead author and founder of IPSO tweeted the article approvingly on 3 October'

Ruth's last para requoted above, while couched in diplomatic prose, is pregnant with implied academic censure. It raises serious questions regarding the evidence base for the emotive soundbite conclusions and the motivation of the authors and organisations supporting and publishing it.

Oct 9, 2013 at 9:00 PM | Registered CommenterPharos

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