A regional approach to the medieval warm period and the little ice age

Very interesting. Although the report says that the last few decades have been the warmest in the last 700-800 years, it is also relevant that this warmth did not suddenly appear in the last few decades at the time when CO2 emissions were greatest, but rather developed slowly over the last two centuries. This argues against a large role for human influence.

Well Nick. Maybe you should shit can those proxies. Because I guaranty you that Greenland was pasture and grapes grew in Labrador during the MWP.

I’ve always wondered just how confident we are in the timing of regional proxies. Yeah, there appear to be some regional differences on timing across those proxies, but how much of that is due to observational error and/or overlapping error bars?
It makes less sense to me that there was a warm period that marched from region to region over a couple hundred years than that we’ve just screwed up the timing of individual regional proxies, artificially creating sine waves that cancel each other out rather than reinforce.

One less person on Gavin’s Christmas list.

Yep, both Hockey Schtick and C3 covered this a few weeks ago:
http://hockeyschtick.blogspot.com/2010/11/paper-medieval-warming-period-hotter.html and http://www.c3headlines.com/2010/11/paleo-climate-scientist-examines-recent-peer-research-determines-all-n-hemisphere-regions-had-large-.html

At the very least this confirms that the issues aren’t clear cut and are probably (my take on what I understood) much more complex than the Alarmists make out.
So, do we once more get back to what often gets lost in the detail: if what is happening now isn’t unique, then we don’t need to look for a historically unique cause e.g. industrial CO2 emissions, that were fingered because (IMO) of general anti – industrial bias plus couldn’t think of anything else so obviously not present before…
My view, shouldn’t this kind of work have been done and argued about before all the alarms were sounded?

eadler says:
I never heard of Fredrik Charpentier Ljungqvist, so I tried to find out using Google. It seems he is a graduate student in the department of history at Stockholm U.
I’m sure if you keep googling you can find some connection between Ljungqvist and “Big Oil”. Maybe his grandfather had greasy hair.

Ljungqvist (Professor, Doctor, what is his title?) is clearly a very level headed guy. This is a good paper, carefully examining the details of the data, and letting it lead to whatever conclusions are justified. That is science. Budding researchers please take notes.

A nice review of the published but, what’s more interesting, also unpublished and non-archived proxies.
And the comment at the page 17, that Briffa’s (2000) Yamal trees show too much of an increase in 20th century compared to other circum-Arctic trees nearby mentioned in Esper et al. (2002) is quite an understatement 😉

I know where you are ‘coming from’ Anthony, however “where are you from?”
and, “what have you published?”
Are moot questions in reality.
If I was back at University, made the right noises in a few places, twisted some arms to get a grant and…………….. if I said, I want to “prove AGW!”
Then I’d be virtually guaranteed (even in these straitened times) a grant, irrespective of my expertise or field, so to me, questions (such as the above) are completely irrelevant.
Lets face it, the IPCC will publish aught (even undergrad’ dissertations and other more dubious sources) if it says the right thing, what’s needed is a new approach to the whole damnable process and we need to start with ‘peer review’.
Some good ideas here:
http://noconsensus.wordpress.com/2010/11/23/how-a-scientific-integrity-act-could-shift-the-global-warming-debate/#more-10878

Is this in press or what?
Eight of 26 pages are references. Just sayin…
Interesting things. Recent May-Sept temps are not as elevated as winter. China and Europe are only regions as warm today as during MWP. That must be where the people most responsible for post-industrial warming are residing. Nice.

The assumption that late 20th century warming is man made rests on two lines of “evidence”:
1. Present warming is unprecedented for the last 2000 years (hockey stick, etc)
2. Climate models can not reproduce 20th century warming without man made CO2 as a decisive factor in the equation.
Both have now been called into question.
1. Present warming is not unprecedented on at least a hemispheric scale.
2. If there was a similar warming 1000 years ago, we know that present warming can also be caused by natural variability, no matter if models can not reproduce it.
It will be interesting to see how the IPCC will deal with this. My guess is that the Team Machine will kick into action, that there will be serial “debunkings” of these results, and that the IPCC will stick to the good old story.

Alan Simpson etc. – tonyb is hardly a paid alarmist . I suggest you review his comments and occasional posts here .

EW says: November 24, 2010 at 4:15 pm
“that Briffa’s (2000) Yamal trees show too much of an increase in 20th century compared to other circum-Arctic”
Those other circum-Arctic trees were missing the necessary Briffa adjustments.
valadj=[0.,0.,0.,0.,0.,-0.1,-0.25,-0.3,0.,-0.1,0.3,0.8,1.2,1.7,2.5,2.6,2.6,2.6,2.6,2.6]*0.75 ; fudge factor
yearlyadj=interpol(valadj,yrloc,x)
densall=densall+yearlyadj
Source of above IDL Source Code:
“FOI2009/FOIA/documents/harris-tree/briffa_sep98_e.pro”.
See Also: http://www.thespoof.com/news/spoof.cfm?headline=s5i64103

Leif… I’d be interested in your thoughts on the following passage starting at the bottom of page 17:
Although it is outside the scope of this article, we can briefly discuss the possible influence of variations in solar and volcanic forcing on the reconstructed temperatures. All the six 18 Climate Change and Variability regional temperature reconstructions show some agreement with the assumed lowfrequency variability in solar forcing of the last 12 centuries (Bard et al., 2000). The medieval period, with high temperatures, had a general high solar activity, whereas the cold LIA was dominated by lower solar activity (Ammann et al., 2007). The warming in the 20th century coincides with an increase in solar forcing, although the warming trend has probably also been amplified in the last decades by anthropogenic greenhouse gas emissions (IPCC, 2007).

Pamela Gray,
Relax, let the ice sublime.

Good paper, So now it is not as bad as was thought!

EW says: November 24, 2010 at 4:15 pm
“that Briffa’s (2000) Yamal trees show too much of an increase in 20th century compared to other circum-Arctic”
Those other circum-Arctic trees where missing the necessary briffa adjustments.
valadj=[0.,0.,0.,0.,0.,-0.1,-0.25,-0.3,0.,-0.1,0.3,0.8,1.2,1.7,2.5,2.6,2.6,2.6,2.6,2.6]*0.75 ; fudge factor
yearlyadj=interpol(valadj,yrloc,x)
densall=densall+yearlyadj
Source of above IDL Source Code:
“FOI2009/FOIA/documents/harris-tree/briffa_sep98_e.pro”
See Also:
http://www.thespoof.com/news/spoof.cfm?headline=s5i64103

Be on the lookout for tampon bombers!
Please don’t ban me for this.
You will make history by not doing so.

eadler says:
November 24, 2010 at 3:15 pm
“I wonder if any climate scientists peer reviewed it. It will be interested to see it deconstructed.”
Why is it only the ones that support CAGW need to be “deconstructed”?
Where is your concern for these papers and their “deconstruction”:
Briffa, 2000; Cook et al., 2004; Crowley and Lowery, 2000; D’Arrigo, 2006; Esper et al., 2002; Hegerl et al., 2007; Jones et al., 1998; Jones and Mann, 2004; Juckes et al., 2007; Loehle, 2007; Mann et al., 1999; Mann et al., 2008; Mann et al., 2009; Mann and Jones, 2003; Moberg et al., 2005; Osborn and Briffa, 2006).

“Less effort has been put into investigating the key question of to what extent earlier warm periods have been as homogeneous in timing and amplitude in different geographical regions as the present warming.”
Is homogeneous really preferable to similar?

Stephen Wilde says:
November 24, 2010 at 2:37 pm
Now, the critical question:
Could every one of those observed regional climate changes be accounted for by a simple latitudinal shift of the air circulation systems above the regions concerned ?
But that also begs another question: What would have caused those shifts?
Further, what would have been the cause (driver) of that particular cause?
To presume one thing of necessity demands that its driver be identified.
It’s not unlike this: The spoon stirred the coffee. A hand caused the spoon to move. The brain of the owner of that hand caused the hand to move and stir the coffee.
If we look only at the spoon, we’ll miss/neglect its driver. Heck we might even misattribute the cause to something entirely unrelated.
With all of the various data which have been collected, and all of the anecdotes (historical references) from ages past, with all of the ice core data and the sun spot data having been analysed, there are few other effects which haven’t been otherwise determined as having affect, such as planetary gravitational influences and the Sun’s current sheets inducing heating in the upper atmosphere by interacting with the Earth’s own magnetosphere.
Knowing what we know already, even if we don’t completely comprehend the lot of it, the correlations in all of the collected information are overwhelmingly in favor of external forces as having the greatest affect upon this planet’s climate and weather.
With the mass of information available, there’s just no way that humans could have caused any of the past events, and since the past events happened when humans weren’t a viable cause for those, and those past events are cyclic in nature, and because the current event is happening with the same periodicity, then there’s no way that humans could even be considered as any kind of agent.
It’s staring us in the face, and yet there are people with a vested interest telling us to ‘Don’t look behind the curtain!!!’
Gee, I wonder why?
Why? They’ll see Al Gore and his banker buddies staring back at us, with the greedy smiles of vampires just waiting for darkness to set in.

I believe that I’ve found an error in Figure 2 based on the data in Tables 1 and 2.
Figure 2 has the “correct” locations for Greenland numbered 10-15 in Table 1.
Based on these six station bounding (lat/lon) coordinates I obtained the following;
81.21N,-69.30W (NE corner)
60.40N,-29.60W (SW corner)
Figure 2 shows E, F, and G as being within these bounding coordinates. While Table 2 shows that the letters for Greenland are actually G, H, and I.
Could someone else, or the author of this paper, check/validate my coordinates/Figure 2/Table 1/Table 2?
If I’m right, and this paper has already been published (physical and/or electronic formats) as is, why didn’t the peer review process/editors catch such a glaringly obvious bookkeeping/tabulation error?
If I’m wrong, oh well, we all make mistakes.

More hockey sticks for the team

Notice, that the “small hockey stick” occurred in 1900-1940 period, when the climate was still virgin. FYI, until 1990 Greenland cooled back to 19th century level and then warmed back to the level of 40ties. Not much of CO2 forcing manifested up there.

Anthony,
In fact, scepticalscience did a pretty good story on Ljungvist 2010 :
http://www.skepticalscience.com/new-remperature-reconstruction-vindicates.html
Which shows the comparison of all major temperature reconstructions, including the ones accumulated for Ljungvist 2010, and the differences and communalities between them.
In contrast, you only show a local temp record from Greenland (sent to you by Scafetta), without any mentioning of any peer-reviewed paper where that graph is presented, nor where the data came from.
And then your story from Ljungvist. What are you trying to prove with that ?
Ljungvist 2010 itself mentions in the conclusions :
“Although partly different data and methods have been used in our reconstruction than in Moberg et al. (2005) and Mann et al. (2008), the result is surprisingly similar. The inclusion of additional records would probably not substantially change the overall picture of the temperature variability.”
So Anthony, the question really is : What are you trying to say in this post, and why are you cherry-picking a local temperature record when the global record is widely different from it, even as confirmed by Ljungvist himself ?

November 24, 2010 at 11:17 pm
Stephen Wilde says:
November 24, 2010 at 2:37 pm
Now, the critical question:
This is something about climate research that has bugged me for ages. When training to be an EE&E1radio engineer my mentor always used to say “go to the source”. I’ll just explain that in case you think its the well :); He used to put faults onto circuits and then I had to find them. Being a youngster, I used to head straight for the component I thought the symptons indicated and invariably got it wrong. Go to the source.
In weather climate you get, for example, ” The cold weather in coming to the UK because the jet stream has moved south” Yes BUT WHY. See what I mean? They never go to the source. In the teams example, its back to the model which they think is the source. Its sooo annoying.

“eadler says:
November 24, 2010 at 3:15 pm
I never heard of Fredrik Charpentier Ljungqvist, so I tried to find out using Google. It seems he is a graduate student in the department of history at Stockholm U.”
So he’s a grad student? In academia the graduate students are typically the ones that do all the work and publish all the papers. The PI typically does the final edits and tacks their name last on the paper. The most successful PI’s (principle investigator) have huge teams of grad students and post docs. The PI’s in these cases are typically way out of the loop in the research: they guide the overall broad research topics and function at a more general level. Except The Team. They are unique in having a closed group of PI’s that publish and referee each other.

Rob, this is the instrumental record from given area:
http://climexp.knmi.nl/data/icrutem3_290-345E_60-85N_na.png
If Greenland (even as a “ground zero” for global warming) is not representing the Northern hemisphere, neither does Mann’s bristlecones.

E.M. Smith says:
“Billy Liar says:
Oh, dear! It may have slipped past the climate gatekeepers.
Here, let me fix that for you…
It may have slipped past the climategate keepers.”
I would suggest the following:
It may have slipped past the climate goalkeeper.
After all they are a team and the previous post suggests they all have their own hockey stick.

Pamela Gray , relax – now you can skate on your back porch .

tonyb says: at 4:25 am
I am seriously concerned at the reading comprehension of some of the people . . .
I’ve made similar comments. My word last time was “astonished.”
Likewise, I was astonished at the remark about you being a “payed” (sic) alarmist.
I also find your posts informative and several are warmly tucked on my hard drive.

@ David Middleton : You are right regarding my comment (in my 2:15 post) on the calibration issue. Thank you for pointing that out.
@ tonyb (4:25) : I am not sure what your issue is with my (1:47) post.
The point I was making had nothing to do with finding Ljungqvist’s Pdf.
The point was that Anthony picked ONE regional graph from that pdf, even though that one is not representative for the larger set that Ljungqvist posts in his pdf, and certainly not representative for the entire Ljungqvist 2010 presentation.
Also, the “skepticalscience” post shows very clearly that the Greenland graph that Anthony prominently posts here is not representative for Ljungqvist’ 2010, nor for the Northern Hemisphere as a whole, and that Ljungqvist 2010 overall shows very close resemblance to Mann 2008 and Moberg 2005.
Anthony could at least have mentioned that, since otherwise some readers may misinterpret what Ljungqvist actually found, and start to see ‘opposite’ hockey-sticks (at cherry-picked time points) in a graph that has no association with the overall Northern Hemisphere reconstructions.

Anthony;
In regard to “eadler” I am compelled to raise the issue of troll quality with you. Both the quantity and the quality have been in decline of late. Could you perhaps put more effort into recruitment? There was a time on this blog when trolls abounded, could carry on a logical discourse, and sometimes even made valid points. One can hardly learn anything from an argument which rests on the premise that a paper may be questionable because it was not peer reviewed by the scientists who wrote papers that are falsified by it.
Not only is the argument so pathetic that it hardly deserves response, it is in fact so pathetic that one can’t even make fun of it. Its just sad really. If you could put some effort into getting some decent trolls, I’d appreciate it.
Until then I shall content myself with rereading accusations that Tonyb is a paid alarmist. Debunked of course by many long before I had a chance, but at least there were some facts on the table to debate, and a conclusion tabled that was so wrong it was hilarious.

Uh huh. That’s just about what the literature indicates happened: The LIA and the MWP were pretty much a global thing, as far as the writings exist. It’s been a slow roll down the hill from the Holocene Optimum.

eadler says:
November 24, 2010 at 3:15 pm
I never heard of Fredrik Charpentier Ljungqvist, so I tried to find out using Google. It seems he is a graduate student in the department of history at Stockholm U.
I wonder if any climate scientists peer reviewed it. It will be interested to see it deconstructed.
Nice logic. The paper (or whatever) reviews regional, previously published studies from around the world. Pardon me, but I thought geography relates to location. Why would a person want a climate scientist to review published geographical proxy studies?
Data is data. We don’t need no stinkin’ opinions.
EFS_Junior says:
November 25, 2010 at 12:31 am
So a couple questions come to mind; 1) Why is this book for free and bot [sic] for sale (behind a pay wall), and 2) this is not published in a well respected peer reviewed climate science journal, why is that, and will the author publish this in something mildly resembling a peer reviewed publication of any sort?
Note, his previous paper (2009 paleo-reconstruction) was published in some rather obscure (IMHO) Scandinavian geography journal.
This journal has a long and storied history. It is well respected in knowledgeable science circles. It is peer reviewed. Appeals to authority are ignorantly misplaced in this instance.
http://www.docstoc.com/docs/43740994/Geography-in-Sweden

Pamela,
Now lets agree that the average temperature of the patient taken over many differents part of the body and different times shows a fever, and most doctors agree that the reason is Antropogenic, just like theory predicted.
Just some people still believe that by looking at checky-picked measurements and cherry-picked areas of the body (and by showing a graph of that area with these measurements on wattsupwiththat) shows that there is nothing unusual going on, and that the patient is somehow immune to the substance that in theory should cause a fever indicative of a desease that can potentially be quite devastating.
Now which “vital information” did I leave out ?

David,
The HADCRUT3 1911-1944 +0.5 C increase started out a whopping 0.4 C below the +0.5 C increase since 1975, and global temperaures thus went up almost a full degree C over the 20th century. That (long-term increase) is the fever that one would expect from antropogenic GHG forcing.
And the graph that you show since the start of the Holocene essentially shows only the GISP2 record. May I remind you that that is a single ice core in one spot in Greenland ? That graph really makes my point that some people cherry-pick ONE location and then feel that it has any meaning for the global temperature record.
At least in the following graph there are 8 proxies combined (from various places on Earth),
http://en.wikipedia.org/wiki/File:Holocene_Temperature_Variations.png
This shows again that Greenland (or any other local record) is not representative for the average of this planet. It also shows (again) that temperatures right now are unprecedented as seen over the entire Holocene record.
Why is this so hard for you (and Anthony) to accept ? Why do you guys keep cherry-picking locations (or time intervals) and pretend that such cerry-picking has any meaning in the global picture ?

David,
I posted the wiki reconstruction (with 8 proxies) just as an example of how irrelevant single-location / single-proxy samples are in the global record.
Even with just 8 proxies, the picture (of the previous “unprecedented” warming periods that you mentioned) looks entirely different. Regardless of the weight by which each proxy is measured, a large sample of proxies irons out the extreme (“unprecedented”) random/weather anomalies of single samples, and reveals the low-frequency climate trends that climate science is interested in.
From signal theory, we know that for N channels (each with uncorrelated, “local” noise) signal to noise ratio for common signals is SQRT(N) better than for a single channel. Meanwhile, local temperature extremes are moderated by a factor of N. From that we know that more (and more physically widespread) samples are quantifiably better than small number of samples if we are interested in ‘global’ or ‘common’ trends.
Even with just 8 proxies on this Holocene record, the long, slow term down trend since the Holocene Climatic Optimum becomes apparent (which is very well explained with the Milankovitch cycles) and the global (+0.7 C in 100 years) climate anomaly of the 20th Century starts to come out of the noise as well.
In that light, I find it mystifying why you throw out 5 of the 8 reconstructions (because they are not in the extra-tropic Northern Hemisphere).
As you very well know, that just increases the noise, and makes it more difficult to recognize climate trends.
Ljungqvist already reduced the number of proxies that he considered (by separating regions, and then again even for the individual regions as well). Then Anthony used the local noise in the Greenland record and the noise that Ljungqvist created by reducing proxies to somehow imply that 20th Century warming is not unprecedented.
And now you are doing the same thing with the Holocene record.
I start to see the pattern that Ljungqvist (at least in this non-peer-reviewed pdf story), Anthony and you are using :
Reduce the number of samples (preferably by cherry-picking) to the point where the local weather noise is greater than the 20th century warming (or to sample size 1, whichever comes first), and then use that to claim that “therefore” the 20th Century warming is not unprecedented or AGW is in doubt.
Of course, you are just fooling yourself (and some readers here) with noise that you created yourself.
Question is, again : WHY are you guys doing that ? Why not find MORE proxies and combine them with the 1000+ proxies (dating back to many different past times) that we already have ? Why reduce the set, create noise, and then imply statistically irrelevant conclusions ?
Why ?