Talk:Description of the Medieval Warm Period and Little Ice Age in IPCC reports

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Can't the page title be abbreviated a bit? Charles Matthews 13:23, 16 Nov 2004 (UTC)

(William M. Connolley 14:56, 16 Nov 2004 (UTC)) Sadly I can't think of a funny answer...

As it stands, this article is seriously flawed. It reads like an advocacy piece, only nothing is sourced. Who has alleged these things? Who has counter-argued? Is this original research documenting what the various reports have said, or has this dispute actually taken place elsewhere besides Wikipedia? --Delirium 09:08, Dec 4, 2004 (UTC)

Needs a better introduction, anyway, William. Charles Matthews 09:29, 4 Dec 2004 (UTC)
(William M. Connolley 11:02, 4 Dec 2004 (UTC)) It is certainly not true that nothing is sourced. The entire piece is heavily sourced. I really don't understand D's comment... unless D means the "it is sometimes alleged..."? Hmmmm... I know these exist. I can find you a wiki source: [1] . Or externally (warning: misinformation).

William, if the 'refutation' of allegation thingy was the reason ... well, just don't go all Lumidek on me (see the loop quantum gravity outrages).

Charles Matthews 16:03, 4 Dec 2004 (UTC)

(William M. Connolley 17:50, 4 Dec 2004 (UTC)) L and I are having a good phase (he has fixed some of the odd wording at gravity) so I'll leave LQG alone. But... if D wants to say what is unsourced, I'll try to source it. For the moment, I'll dump in the Daly ref.

Fig 7 from 1990[edit]

So, we're arguing about fig 7 from the 1990 IPCC report. I say:

The vertical temperature scale was labelled as "Temperature change (°C)" but no numerical labels were given;

SEW doesn't like the "no numerical labels" bit. But, its important. AFAIK its the only graph in the report not explicitly numerically labelled: this is important as evidence of its schematic character. If you want to try to work out what units in, you have to second-guess it from the text. William M. Connolley 18:24:32, 2005-09-01 (UTC).

The units are specified as being degrees C, on all three graphs. The axis marks for each degree shift appropriately for the various time periods. You can read the graph without the text, and the text confirms the meaning of the graph labels. (SEWilco 06:55, 2 September 2005 (UTC))
*There are no numerical labels*. As in, numbers written on the graph axes. Do you accept that? William M. Connolley 08:27:45, 2005-09-02 (UTC)
Yes, there is no "1, 0, -1". Do you accept that there is one tick mark per degree C? (SEWilco 15:34, 2 September 2005 (UTC))
It may be possible to deduce it from the surrounding text, but not from the figure itself. Which is why my edit is correct. Be so kind as to explain why you object to but no numerical labels were given given what you hv just said. William M. Connolley 15:51:42, 2005-09-02 (UTC).
It is quite obvious from the figures, which are labeled "(°C)" next to the tick marks which show each °C. The graphs are marked in degrees. No numerical labels are given, and their not being there is as irrelevant as there not being marks for fractions of degrees or marks for °F. (SEWilco 16:21, 2 September 2005 (UTC))
You are being quite obtuse. Can you point to another graph from IPCC '90 which has no numerical labels? The graphs have no labels; this is unusual, and significant (which is why you are removing this information which is inconvenient to your POV). William M. Connolley 18:22:52, 2005-09-02 (UTC).
The graphs and their text do not indicate there is significance in the format of these graphs. Where are you finding the report stating that these graphs are different from others? (SEWilco 20:18, 2 September 2005 (UTC))
On the contrary, if you examine the '90 report, fig 7 is quite unique in lacking numerical labels (well, I've challenged you to find another: let me know when you succeed. I've just flicked through ch 7, and none of the others there lack explicit numerical labels (and just to be completely honest, I'mgoing to slightlyqualify that: 7.2 is halfway: but it is sourced William M. Connolley 09:48:40, 2005-09-03 (UTC))), which fits with it being vaguely defined as "schematic" and completly unsourced. Its really very funny: if this graph had been in the TAR, M&M and all the septics would be *attacking* it as totally unreliable, unsourced, and unlabelled. William M. Connolley 20:59:55, 2005-09-02 (UTC).
So where does the report vaguely define it as "schematic"? (SEWilco 21:07, 2 September 2005 (UTC))
have you actually read the thing? The caption is: "Figure 7.1. Schematic diagrams...". William M. Connolley 21:14:40, 2005-09-02 (UTC)
Hey, you can read labels. No text definition of what its being "schematic" means? (SEWilco 03:23, 3 September 2005 (UTC))
Presumably it has the commonplace meaning. If you're objecting that "schematic" is vague, then fine. William M. Connolley 09:48:40, 2005-09-03 (UTC).

Drawing conclusions in the intro[edit]

Old intro:

The description of the Medieval Warm Period and Little Ice Age in IPCC reports has changed since the first report in 1990 as scientific understanding of the temperature record of the past 1000 years has improved. The Medieval Warm Period (MWP) and Little Ice Age (LIA) are the best-known temperature fluctuations in the last millenium.

Critics of the "hockey stick graph" of later reports have claimed that the record of the MWP and LIA were suppressed in the IPCC Third Assessment Report, although every report has discussed the phenomena.

Who says that scientific understanding of the temperature record of the past 1000 years has improved? The UN climate panel?

The combination of "critics ... claimed" and "every report has discussed" is tantamount to saying:

  • The critics are wrong: they claimed X is true, but actually X is not true

This is the sort of synthesis which is forbidden by WP:OR and/or Wikipedia:Attribution. We can't conclude that "critics are wrong" on our own. --Uncle Ed 19:21, 20 March 2007 (UTC)

Ed, this is just silly. If you're going to do silly things like this, do them properly. Why haven't you struck out "The Medieval Warm Period (MWP) and Little Ice Age (LIA) are the best-known temperature fluctuations in the last millenium" on the grounds that its unsourced? Because... we all know its true. It doesn't need a source. Ditto the improvements in understanding. In your "the combination..." bit you are correct: the critics are indeed wrong. This is reality. But you can't just strike out the perfectly true (and sourced in the article) every-report-has-discussed just because it makes the critics you like look silly. Also, I reverted the move: description is to my mind better William M. Connolley 20:07, 20 March 2007 (UTC)
No, I think that sentence does need a source. Many laymen think that the hockey stick obliterated the temp fluctuations. It would be nice to have two images: one showing the MWP and LIA as the large fluctuations that some scientists think it is - the other showing them as small or non-existent, as some others think it is.
Unless, of course, there is unanimity on the degree of size of the hills and valleys. Which would have to be sourced. Which brings us back to the question: is there unanimity on this point? If so, who says so? --Uncle Ed 21:06, 20 March 2007 (UTC)
You're being silly William M. Connolley 21:11, 20 March 2007 (UTC)
The phrase "every report has discussed the phenomena[LIA and MWP] " seem to be contradictory to the phrase about the 1990 report, "The MWP is not mentioned at all" and the 1992 supplement's graph which "...stops in 1350 and does not show an MWP.". Also, "The 1995 IPCC report used a northern hemisphere summer temperature reconstruction (fig 3.20) from 1400 to 1979 by Bradley and Jones (1993). This too shows no MWP (it only goes back to 1400)". The claim that the MWP and the LIA are discussed in every report does not seem to fit with reality.Tyr Oathkeeper (talk) 00:47, 16 April 2009 (UTC)
Try reading it again. The SPM is a not the complete report - but a chapter of the report summarizing it. (ie. lots of data in the report will not be in the SPM). --Kim D. Petersen (talk) 00:54, 16 April 2009 (UTC)
BUT the SPM is all that is read by most, so it's impact far outweighs its veracity (or lack there of) -as you well know. Cheers (talk) 10:55, 10 June 2009 (UTC)
The SPM might be the most widely read part of the report, but that doesn't invalidate statement about the report. Its also quite simple that the SPM as a summary cannot contain every item in the full report, and that the name "Summary for policymakers" makes it quite clear what it is. Analogy: The most widely read part of any book, is the summary on the back or the inside sleeve, that doesn't make a statement about a book incorrect (or correct) if it isn't in the summary. --Kim D. Petersen (talk) 13:41, 10 June 2009 (UTC)


could few third party sources be added please. thanks. (talk) 21:23, 6 December 2009 (UTC)

Typo suspected[edit]

As I proofread Japanese edition (which volunteer editors other than me have translated from this English edition), I suspect a couple of typo errors in the present text of this article (English edition). Would anyone check these?

1992 Supplement: "two graphs or pre-instrumental temperatures". The sentence seems much more understandable if "or" is replaced by "of".

2001 Report (TAR): References "Jones et al. (1999)" and "Jones et al. (1998)" exist. I guess that the year should be 1998 in both cases. The reference list of Chapter 2 of TAR does contain "Jones et al. (1999a,b,c)", but they are not referred to in Section 2.3.3, and the titles suggest that they have different subject.--Masudako (talk) 18:32, 16 February 2010 (UTC)

Thanks. Of for Or, agree. 99 -> 98 agree. In the course of this I followed the link and we seem to have the wrong pic. We want fig 2.21, which [2] gives you, even if the link suggests it should be 2.20. Odd William M. Connolley (talk) 20:48, 16 February 2010 (UTC)
Thank you very much. --Masudako (talk) 05:23, 17 February 2010 (UTC)

References added to the Japanese edition[edit]

The Japanese edition of this article is currently a translation of this English edition 'with references added'. At present all references are in English and valid for this English edition as well. (They will diverge sooner or later.) I am sorry I am not going to edit the English edition similarly. (Also note there may still be some inconsistency in the format of the list.) --Masudako (talk) 05:23, 17 February 2010 (UTC)

Fig 7.1.c (again)[edit]

[3] refers; someone says:

The appendix in Jones et al. 2009 (“High-resolution palaeoclimatology of the last millennium: a review of current status and future prospects” The Holocene, 19, 3-49) tries to describe where the IPCC 1990 Fig. 7c comes from.

They conclude that it was compiled from a series of publictions by H. H. Lamb and was only based on temperature records associated with Central England, so not global.

Further, Jones et al. point out that “At no place in any of the Lamb publications is there any discussion of an explicit calibration against instrumental data, just Lamb’s qualitative judgement and interpretation of what he refers to as the ‘evidence’”.

I haven't read the paper myself William M. Connolley (talk) 10:55, 21 June 2010 (UTC)

Critics of the "hockey stick graph" of all subsequent reports have claimed that the record of the MWP and LIA were suppressed in the IPCC Third Assessment Report...[edit]

This really ought to have a source. We used to use Daly but that's gone; perhaps he was too obviously a nutter William M. Connolley (talk) 21:50, 20 June 2015 (UTC)