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« Subprime science | Main | Harrabin on the Jones interview »
Sunday
Feb142010

Jones on the Medieval Warm Period

It's interesting to compare Phil Jones' various prognostications on the reality or otherwise of the Medieval Warm Period.

Jones et al 1998:

..we can only concur with Hughes and Diaz (1994) that there is little evidence for the
‘Medieval Warm Period’, although it is variably quoted as occurring between 900 and 1200...From the few reconstructions used prior to 1500 there is little evidence for the ‘Medieval Warm Period’.

Jones and Mann 2003:

To the extent that a ‘Medieval’ interval of moderately warmer conditions can be defined from about AD 800–1400, any hemispheric warmth during that interval is dwarfed in magnitude by late 20th century
warmth.

Jones & Mann 2004:

Our assessment affirms the conclusion that late 20th century warmth is unprecedented at hemispheric and, likely, global scales.

BBC interview 2010:

There is much debate over whether the Medieval Warm Period was global in extent or not. The MWP is most clearly expressed in parts of North America, the North Atlantic and Europe and parts of Asia. For it to be global in extent the MWP would need to be seen clearly in more records from the tropical regions and the Southern Hemisphere. There are very few palaeoclimatic records for these latter two regions.

One striking feature of the recent statements are that the disappearance of the scare quotes from the medieval warm period. But the overall tone has changed too. This looks like a pretty clear change of emphasis to me, but I'm sure that there are those who will argue that his latest statement is, in Hockey Team jargon, "consistent with" his earlier positions.

 

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Reader Comments (33)

Does anyone want to come and find some tree ring data with me in NZ? I think I need to get out more anyway.

Feb 14, 2010 at 8:00 PM | Unregistered CommenterAndy Scrase

The Mail Online seems to be emphasizing the Jones admission that there has been no statistically significant global warming in the last 15 years.

Feb 14, 2010 at 8:14 PM | Unregistered CommenterKevin

It should be mentioned that one of the hallmarks of a good scientist is the willingness to change your mind when presented with new evidence. Doing so after you have been rumbled and your position has become untenable may carry less merit however. The question therefore may be: Does he merit us giving the benefit of the doubt?

Feb 14, 2010 at 8:31 PM | Unregistered CommenterStonyground

“We talk about climate deniers being the sceptics but actually the true sceptics are the scientists themselves,” said Prof Liss.

Prof Liss said there is no better system, at present, to check what scientists do is right than by asking other scientists who are equally, or even better, informed to look into it and establish it has been done properly.

“We scientists are somewhat on the back foot and its partly our own fault because we are not as willing as perhaps we ought to be in speaking to the media and so we are receiving questions and answering them when perhaps we should be setting the agenda. The so-called climate sceptics are not so inhibited; they are much more up front with saying 'we know climate is not changing and we don't need to do anything' which is a very arrogant position to take. Many of them are not scientists, their opinion is against a huge body of scientific information

“When you simplify something it can mean you have to try to concentrate on the important messages and perhaps not on the uncertainties which are there. I think it's that balance that we have not quite got right so far between the message that 'the science says the globe is warming, it's mainly due to man's activities and we need to do something about it' and 'there are some of the uncertainties in the system' which we should talk about in a more open way.

Professor Liss is out of his league the confusion is endemic its an AGW thing, please do not treat us as greenhorns!

http://www.edp24.co.uk/content/edp24/news/story.aspx?brand=EDPOnline&category=NewsSplash&tBrand=EDPOnline&tCategory=xDefault&itemid=NOED12%20Feb%202010%2014%3A02%3A02%3A740

Feb 14, 2010 at 8:35 PM | Unregistered CommenterLord BeaverBrook

Lord Beaverbrook

I agree that if the facts change then he should change his mind. I'm just not sure if he has changed his mind yet.

Feb 14, 2010 at 8:37 PM | Registered CommenterBishop Hill

Jones, Mann, et al climategate emails relating to the MWP, in response to a paper in Science 2001 "Was the Medieval Warm Period Global?" and a subsequent blog posting:

http://hockeyschtick.blogspot.com/2010/01/blog-post_26.html

Feb 14, 2010 at 8:44 PM | Unregistered CommenterMark Sawusch

Perhaps science needs an advocacy system like our courts, especially when it's something that's affecting us all so much. Peers, generally, tend to agree with each other.

... Not just for global warming either, but for those drugs with pharmaceutical giants behind them, the first question for the prosecution being, "Why that price for production line produced pills?"

Feb 14, 2010 at 8:49 PM | Unregistered CommenterNeal Asher

Now I am confused.
Wikipedia http://en.wikipedia.org/wiki/Medieval_Warm_Period
(not exacly neutral on this issue)
states that
(a)"Temperatures derived from an 18O/16O profile through a stalagmite found in a New Zealand cave (40.67°S, 172.43°E) suggested the Medieval Warm Period to have occurred between AD 1050 and 1400 and to have been 0.75°C warmer than the Current Warm Period."[22] The MWP has also been evidenced in New Zealand by an 1100-year tree-ring record

but here states:
(b).[5] Crowley and Lowery (2000) [6] note that "there is insufficient documentation as to its existence in the Southern hemisphere."


From my initial observation, it seems the argument seems based on lack of data, rather than existence of data. The other argument seems to be some evidence in cooling in other parts of the world during this period.Can we categorically say that the world has been warming at a uniform rate in the current era, and this was not the case in the MWP?
Australia is a very harsh environment and fires are common, so ancient tree ring data may not exist for all I know.

I'd be interested to see some more impartial info. References to Mann in Wikipedia don't exactly inspire me.

Feb 14, 2010 at 8:59 PM | Unregistered CommenterAndy Scrase

I am more worried that he is following a political agenda rather than looking at the science. If we can move forward from this debacle it takes all parties to realise that the way forward is non political.
Surely everyone who has taken an interest must realise that the way forward has got to be unbiased evidence that cannot be refuted. I am not a scientist I am a tax payer who pays the bill I expect two things the first is scientists to produce the best current knowledge without bias. The second is I expect that knowledge to benefit mankind as a whole rather than a political agenda. I don't ask for much but I hope I get what I pay for.

Feb 14, 2010 at 9:03 PM | Unregistered CommenterLord BeaverBrook

Kevin,

"The Mail Online seems to be emphasizing the Jones admission that there has been no statistically significant global warming in the last 15 years."

You misspelled 'misrepresenting'. You wrote 'emphasizing'.

Bishop,

I'm sure that there are those who will argue that his latest statement is, in Hockey Team jargon, "consistent with" his earlier positions.

I agree that people will argue this, since they'd obviously be right.

Feb 14, 2010 at 9:05 PM | Unregistered CommenterFrank O'Dwyer

Frank, a direct quote from the BBC website:

B - Do you agree that from 1995 to the present there has been no statistically-significant global warming

Yes, but only just. I also calculated the trend for the period 1995 to 2009. This trend (0.12C per decade) is positive, but not significant at the 95% significance level. The positive trend is quite close to the significance level. Achieving statistical significance in scientific terms is much more likely for longer periods, and much less likely for shorter periods.

Sure he adds caveats, but he unquestionably agrees that "from 1995 to the present there has been no statistically-significant global warming".

Feb 14, 2010 at 9:18 PM | Unregistered CommenterJonathan

At the rate he is changing his mind, in a matter of weeks he'll be a full blown skeptic claiming we are on the cusp of the next ice age !

Feb 14, 2010 at 9:31 PM | Unregistered CommenterFred from Canuckistan

Jonathan,

Sure he adds caveats, but he unquestionably agrees that "from 1995 to the present there has been no statistically-significant global warming"

And the Mail omits both the caveats and the point about statistical significance.

Nor do they seek the opinion of any other experts - Jones answer was pretty poor and doesn't even specify what data set he is talking about.

He also seems to be assuming a good faith reading of his remarks - he of all people should know better by now.

Feb 14, 2010 at 9:33 PM | Unregistered CommenterFrank O'Dwyer

Here’s one for you Frank.
Climate scientist says Himalayan glacier report is 'robust and rigorous'
http://www.guardian.co.uk/environment/2010/feb/14/climate-scientist-himalayan-glacier-report
Talk about wriggling!

Feb 14, 2010 at 9:57 PM | Unregistered Commentermartyn

martyn


Climate scientist says Himalayan glacier report is 'robust and rigorous'
http://www.guardian.co.uk/environment/2010/feb/14/climate-scientist-himalayan-glacier-report
Talk about wriggling!

He's talking about the WG2 report and not the Himalayan claim - really dumb headline from the Guardian. The journalism from all sides on this has been pretty crap.

That said I wouldn't say the WG2 report was 'robust' either, it is definitely a lot less solid than the WG1 report.

Feb 14, 2010 at 10:06 PM | Unregistered CommenterFrank O'Dwyer

Frank, the Mail says "And he said that for the past 15 years there has been no ‘statistically significant’ warming.". I'm afraid I'm really struggling to understand your point. Jones also pretty much states that he is using HADCRUT.

Feb 14, 2010 at 10:11 PM | Unregistered CommenterJonathan

"Nor do they seek the opinion of any other experts - Jones answer was pretty poor and doesn't even specify what data set he is talking about."

Pardon me, Frank, but isn't the issue being addressed that of the methodology of the UEA CRU, and specifically, Jones as its Director? Why then would one seek the opinion of "other experts?"

Is the effort now to marginalize Jones as some peripheral, non-influential player?

Feb 14, 2010 at 10:27 PM | Unregistered CommenterJBean

This is what it's about!

A year after that, the D-Day landings were only possible because Met Office scientists forecast a brief lull in horrendous Channel storms. In 1952 the acquisition of the J Lyons Company paper-tape computer known as LEO enabled the Met Office to make its first successful 'numerical' forecast based on the laws of physics (a feat attempted unsuccessfully during World War I by the brilliant British meteorologist Lewis Fry Richardson using pencil and paper).

The Americans were slightly ahead of us using their experimental computer ENIAC, and a weather race was on. Unlike in rocketry (remember Blue Streak?), Britain stayed in the race, adding satellite capability as that came on stream in the Seventies, and our meteorological pre-eminence remains an important projection of British 'soft power' to this day.


Read more: http://www.dailymail.co.uk/home/moslive/article-1249957/The-Met-Offices-33-million-supercomputer-keeps-Britain--world--turning--Now-try-complaining-forecast.html#ixzz0fYOizXjI

Feb 14, 2010 at 10:58 PM | Unregistered CommenterLord BeaverBrook

"One striking feature of the recent statements are that the disappearance of the scare quotes from the medieval warm period." I'm not sure that Phil Jones is capable of putting scare quotes into his spoken words. Were all of these written?

[BH adds: The scare quotes were from journal articles. The Harrabin interview appears to have been done in writing via email]

Feb 15, 2010 at 1:41 AM | Unregistered CommenterMikeR

By his own admission, Prof. Jones has not changed his mind, nor has his base data changed.

First, since he knew all along that The Team's AGW hypothesis was riddled with ambiguities if not outright falsehoods, his interim statements over ten years were a mere PR exercise on behalf of a self-interested agitprop agenda; he has changed his story, not his carefully undisclosed opinions.

Second, let's face it: Briffa, Hansen, Jones, Mann, Trenberth et al. had no valid base-data to begin with. Everything they cited, from spurious dendrochronology to temperature readings, was either a complete fabrication or so selective and manipulated as to be virtually worthless. Garbage in, garbage out (GIGO), without a grain of truth or even common sense, regardless of blatantly collusive "peer review".

Mea culpas notwithstanding, these Luddit sociopaths deserve no sympathy. But for the accident of Climategate their vicious smears and rants would echo yet. Pachauri's turgid IPCC remains in place, a cesspool of corruption even to the UN's idiotic Ban Ki-moon. [Recall his statement last September that unless the UN received ten trillion dollars within weeks (yes, trillion-- and for what?), Planet Earth would become a baking desert by New Year's Day 2010.] Get 'em outta here!

Feb 15, 2010 at 2:30 AM | Unregistered CommenterJohn Blake

"For it to be global in extent the MWP would need to be seen clearly in more records from the tropical regions and the Southern Hemisphere"

How much of Mann's hockey stick data came from tropical regions and the Southern Hemisphere?

Feb 15, 2010 at 4:38 AM | Unregistered CommenterGracco

Jonathan,

Frank, the Mail says "And he said that for the past 15 years there has been no ‘statistically significant’ warming.". I'm afraid I'm really struggling to understand your point. Jones also pretty much states that he is using HADCRUT.

OK let me try to put it more clearly. Here are two different statements:

1) There has been no statistically significant global warming since 1995 (what Jones actually said - and the caveats also add information)
2) There has been no global warming since 1995 (what the mail twisted this into)

There is no way to reason from (1) to (2). In fact, (1) is actually evidence that (2) is very likely to be false.

What statement (1) actually means is that there is only a little more than a 1 in 20 chance that since 1995 global temperatures stayed flat or cooled, and 'only' a little less a 95% chance that it warmed.

To support (2), which is a categorical statement that it has not warmed, you need, at minimum, a statistically significant result that says so. That is, you need to show a flat or cooling trend and an error range that excludes warming. Nothing remotely like this has been seen. Indeed the 'statistical significance' statement provided by Jones is far more forceful against claim (2) than for it.

Feb 15, 2010 at 1:54 PM | Unregistered CommenterFrank O'Dwyer

Frank, my text


And he said that for the past 15 years there has been no ‘statistically significant’ warming.

is a direct quote for the article in the Daily Mail. Please stop misrepresenting what they said; it doesn't impress anyone.

Feb 15, 2010 at 2:08 PM | Unregistered CommenterJonathan

Jonathan,

What is the article's headline?

Feb 15, 2010 at 2:35 PM | Unregistered CommenterFrank O'Dwyer

So you are not complaining about the article, you are only complaining about the headline? You do understand, I assume, that headlines are written by sub-editors to be deliberately provocative, and that you have to read the article if you want to know what the writer meant?

Feb 15, 2010 at 2:45 PM | Unregistered CommenterJonathan

Jonathan,

"You do understand, I assume, that headlines are written by sub-editors"

I understand that they are not written by me. Do you? If so then why do you accuse me of misrepresenting what the Mail says, when I directly quote them? Which paper do the sub-editors work for?

They say it again under the headline in a bullet point by the way, just in case you didn't hear them the first time.

"to be deliberately provocative"

I suppose a complete falsehood is pretty provocative. Though it doesn't seem to have provoked you much. You seem to think it's all hunky dory.

Your surname isn't Leake, by any chance, is it?

Feb 15, 2010 at 3:22 PM | Unregistered CommenterFrank O'Dwyer

Frank, let's recall where we started. Kevin said

The Mail Online seems to be emphasizing the Jones admission that there has been no statistically significant global warming in the last 15 years.

You replied
You misspelled 'misrepresenting'. You wrote 'emphasizing'.

implicitly accusing Kevin of misrepresenting what the Mail said. I pointed out that
Frank, the Mail says "And he said that for the past 15 years there has been no ‘statistically significant’ warming."

i.e., that Kevin had accurately quoted the Mail. You then patronised everyone in sight with some rather irrelevant statistical statistical musings (which were also a tad bizarre: you do realise, I assume, that a flat trend cannot rule out warming if it there is any noise at all?) while completely ignoring my point. Finally you decided to reveal that you were not in fact complaining about the overall accuracy of the article, but only about the headline (it might have helped if you had mentioned this slightly odd take a little earlier).


I really, really, can't understand what you think you are achieving by flogging this particular dead horse.

Feb 15, 2010 at 3:54 PM | Unregistered CommenterJonathan

Jonathan,

"implicitly accusing Kevin of misrepresenting what the Mail said."

Nope. This is just complete reading comprehension failure on your part. I accused the Mail of misrepresenting what Jones said. Which of course they did.

"i.e., that Kevin had accurately quoted the Mail"

Kevin didn't quote the Mail at all. I did however and you (explicitly) accused me of misrepresenting what they had said.

Since I didn't do that you can apologise for that whenever you like.

"Finally you decided to reveal that you were not in fact complaining about the overall accuracy of the article"

Also wrong.

You're not getting much right here, are you? I suggest you withdraw your false claims and apologise for them before making more,. Then perhaps you can tell us why it's OK for the Mail to mispresent Jones as long as their subeditors do it.

But do whatever you like.

Feb 15, 2010 at 4:38 PM | Unregistered CommenterFrank O'Dwyer

Let's not forget Phil Jones in the CRU e-mails, October 22, 2004:

Bottom line - their is no way the MWP [Medieval Warming Period] (whenever it was) was as warm globally as the
last 20 years. There is also no way a whole decade in the LIA [Little Ice Age] period was more than 1 deg C
on a global basis cooler than the 1961-90 mean. This is all gut feeling, no science, but
years of experience of dealing with global scales and varaibility.

Let's all spend billions of dollars based on Phil's gut feeling.

Feb 15, 2010 at 4:54 PM | Unregistered CommenterLloyd W. Robertson

Let's not forget Phil Jones in the CRU e-mails, October 22, 2004:

Bottom line - their is no way the MWP [Medieval Warming Period] (whenever it was) was as warm globally as the
last 20 years. There is also no way a whole decade in the LIA [Little Ice Age] period was more than 1 deg C
on a global basis cooler than the 1961-90 mean. This is all gut feeling, no science, but
years of experience of dealing with global scales and varaibility.


Let's all spend billions of dollars based on Phil's gut feeling.

Feb 15, 2010 at 4:54 PM | Unregistered CommenterLloyd W. Robertson

Let's not forget Phil Jones in the CRU e-mails, October 22, 2004:

Bottom line - their is no way the MWP [Medieval Warming Period] (whenever it was) was as warm globally as the
last 20 years. There is also no way a whole decade in the LIA [Little Ice Age] period was more than 1 deg C
on a global basis cooler than the 1961-90 mean. This is all gut feeling, no science, but
years of experience of dealing with global scales and varaibility.


Let's all spend billions of dollars based on Phil's gut feeling.

Feb 15, 2010 at 4:55 PM | Unregistered CommenterLloyd W. Robertson

A good scientist changes his mind/theory when the facts have changed.

Unlike ethical scientists it would appear that Jones (and friends) have for many years tried changing the facts and keeping the theory the same but have now been rumbled. So they are belatedly going back to the correct way of doing things and slowly shifting their position to fit the facts as they really are rather than as they would wish them to be.

It's encouraging to see them do this but I'm not sure they deserve much praise (1 cheer perhaps) as this isnt really a voluntary shift on their part. More a forced migration than a journey.

Feb 16, 2010 at 11:31 AM | Unregistered CommenterJohnRS
Aug 11, 2010 at 10:55 AM | Unregistered CommenterArkadaslık sitesi

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