Yes, I know, I covered it first: The Medieval Warm Period was Global

I must have had 20 tips and notes/contacts over the past 24 hours like this one:

New temperature proxy discovered

An article ( in the Mail Online describes a paper ( detailing a new temperature proxy that indicates that the Medieval Warm Period was global, not merely regional.

WUWT had the story first, 5 days ago on March 22nd. Somehow a lot of people missed it, so I’m linking to it again. Read it here: More evidence the Medieval Warm Period was global

And I have more graphs and information from the actual paper than the Daily Mail has.

UPDATE: 3/30/12 Since a number of commenters that are getting bent out of shape over the issue can’t apparently be bothered to read the paper, and since the authors at Syracuse themselves are under pressure because the alarmosphere has gone ballistic over the possibility that Mike Mann’s “there is no MWP much less global” gospel might be challenged, I offer readers this passage from the actual paper:

The resolution of our record is insufficient to constrain

the ages of these climatic oscillations in the Southern

hemisphere relative to their expression in the Northern hemisphere, but our ikaite record builds the case that the oscillations of the MWP and LIA are global in their extent and their impact reaches as far South as the Antarctic Peninsula, while prior studies in the AP region

have had mixed results.

I realize that because the authors chose a really poor place to publish it, in Elsevier, which is being boycotted worldwide for their draconian policies on scientific publishing, that many people haven’t read the actual paper, but instead rely on others to interpret it for them, sparing them the effort of having to think or investigate for themselves. Of course the same sorts of people that claim my headline is wrong won’t believe the passage I’ve cited above, therefore I’m reproducing page 114 of the journal Earth and Planetary Science Letters 325–326 (2012) with the relevant passage highlighted:

Some media (The Daily Mail for example) have oversold the conclusions of the paper, and thus this is why the authors have issued a statement. Based on their words above in their own paper,  I stand by my headline.  Note that the authors at Syracuse have NOT asked me to change my headline nor any part of my post on the issue. – Anthony


newest oldest most voted
Notify of

and during the “Medieval Warm Period,” approximately 500 to 1,000 years ago.
someone needs to re-write the history of the Incas and Machu Picchu

Ken Hall

“And I have more graphs and information from the actual paper that the Daily Mail has.”
That’s not difficult is it? But sincere congratulations on breaking this news WAY first! This is why I come to WUWT everyday, and not the Daily Mail.


I figured you’d be inundated with that story, even Drudge ran it! Also, found it interesting that a former hedge fund manager is planning a huge vineyard/winery to produce sparkling wine in England. They are supposed to compete with the better champagnes. Someone is betting on ‘global warming’ sticking around for a while! I don’t think European wineries did so well during the solar minimums. Interesting times


Global, but not synchronous.

Wrong. Synchronous.


And Mann just happened to pick the only trees where the MWP didn’t occur – what are the odds ….

John W.

Cut Mann some slack. It isn’t like there’s any theory, let’s call it the Law of the Maximum, that he and his pals could have applied to test whether tree growth could have been affected by something else.


Antony, just when we though we had atmospherics worked out:-
Lightning strikes produce free neutrons, and we’re not sure how

Gail Combs

Read it the first time. This is a good example of why it pays to read WUWT.

Chris B

Hockey stick wielding Michael Mann KO’d by Kaolinite crusader, Dr. Lu.
What will Supermanndia do next?

seriously doubt the mental processes of those involved

Pardon me for being a very stupid, totally no climate science ordinary person, but my problem with the issue called “global warming” is the word global. I have no trouble with the idea that climate changes, but I do have a problem with the, in my opinion utterly stupid idea, that it changes all over the globe in the same direction at the same time. Ice ages do not involve a world covered in snow and ice. It gets cooler pretty much everywhere, but it does not freeze everywhere, self evidently as nothing would have survived and many things did. Pleeeeeese can we stop talking about “global” climate, please, please, pretty please!!!!

Another good proxy shown on the WUWT more than a year ago
Time someone paid a bit of attention


This is the abstract of the paper:
Calcium carbonate can crystallize in a hydrated form as ikaite at low temperatures. The hydration water in ikaite grown in laboratory experiments records the δ18O of ambient water, a feature potentially useful for reconstructing δ18O of local seawater. We report the first downcore δ18O record of natural ikaite hydration waters and crystals collected from the Antarctic Peninsula (AP), a region sensitive to climate fluctuations. We are able to establish the zone of ikaite formation within shallow sediments, based on porewater chemical and isotopic data. Having constrained the depth of ikaite formation and δ18O of ikaite crystals and hydration waters, we are able to infer local changes in fjord δ18O versus time during the late Holocene. This ikaite record qualitatively supports that both the Medieval Warm Period and Little Ice Age extended to the Antarctic Peninsula.
I’m sorry, but the reliability of that proxy seems in doubt. The calibration experiments have to replicate actual conditions. The crystals must have not been contaminated and the 18O concentrations have to vary only with temperature. The sediments must not have mixed or moved over time. And after all that, the results are only qualitative, in that the proxy seems to be higher a thousand years ago than it was five hundred, and so on.
If the last line of that abstract read “This idaite record qualitatively supports that neither the Medieval Warm Period or the Little Ice Age extended to the Antarctic Peninsula,” then everyone who reads this blog would have jumped on the doubtful reliability of the proxy.
WUWT is not supposed to be Selectively Skeptical Science.

ExPat Alfie

If I’d read it in the Daily Mail first would I have found it credible? Probably not.

Alan S. Blue

It’s worth pointing out that this is important primarily because of Mann et al.’s work. Mann’s method does, and will always, find very little variation in all periods that aren’t ‘the test period’. There are extensive historical treatises on extent and intensity for both the LIA and MWP that were relegated to ‘anecdotal evidence’ by Mann. Even thousands of actual proxies are devalued to near-zero impact by the technique applied.
That is: If you break the hockey stick into two pieces, the ‘shaft’ and the ‘blade’, it really doesn’t matter -what- was going on during the ‘blade’ years, you’re fundamentally going to find a flat shaft.
Finding good agreement during the blade years is hardly shocking. But the ‘shaft’ is both an extrapolation and an assumption that ‘the divergence problem’ hasn’t happened before in periods where we do -not- have satellites to tell us “hey, that tree isn’t working as a temperature proxy.”
Which is why it is important to catalog scientific contrary positions about the ‘globality’ of the MWP/LIA.


John W. says:
March 27, 2012 at 8:21 am

Cut Mann some slack. It isn’t like there’s any theory, let’s call it the Law of the Maximum, that he and his pals could have applied to test whether tree growth could have been affected by something else.

Not sure that’s a viable argument–certainly not a viable excuse. Mann put his selfish interests ahead of science and resorted to all sorts of devious methods–including refusing to be vetted by more capable scientists and mathemeticians in augmenting fields. Mann’s motivation could have been several of the seven deadly sins, but I haven’t wanted to delve deeply into a dude that’s so disturbed.
Right now, Mann’s situation reminds me of a WWII general who famously stated:
“I knew we were in trouble because our glorious victories kept getting closer to Berlin.”
We’ll see if Mann (supposedly a geologist) will bow to geological evidence and withdraw and disavow his hockey stick. Otherwise, even his closest colleagues will abandon and eventually despise him.


My first thought when I saw it on Drudge… Tell Anthony…nope, click the link…read the article…then tell Anthony…then I think…What’s the date on the article…and they are talking about some scientific article…I am sure I will find something on WUWT in the morning…
Yo Drudge…keep up the good work, but check out WUWT, maybe even add a link. Sorry, no Page Six girls or Transgender beauty queens… maybe something about hermaphroditic nematodes or something. Oh…and even Vampire Bats!

James Ard

What I don’t understand is when you are making a case that co2 drives temperature, why would you use a proxy like trees, which are affected by both temperature and co2 concentration? It seems too confusing to make sense of.

Brian H

“And I have more graphs and information from the actual paper that than the Daily Mail has.”

Brian H

“And I have more graphs and information from the actual paper than the Daily Mail has.” Necessary because you know you’re addressing a MUCH smarter audience.


Something geologist have taught for years in South America.

Alan the Brit

Ah, but I thought they had eradicated the MWP? There’s that Hockey Stick thingamabobyou see! PROVES it never existed! I was under the impression that there was plenty of alternative evidence demostrating that the MWP was global, from northern Europe to Australia, from South America to China. This new breakthrough simply endorses that earlier evidence rather spectacularly!


Mr. Watts, modesty is a virtue. That said, congratulations for remaining objective in the face of an overwhelming “consensus.” History does indeed repeat itself. This time, the establishment is in the minority.
REPLY: wasn’t really trying to blow my own horn, just appeasing the people who keep writing and saying “why aren’t you covering this!!??” – Anthony

Uh, well, the hockeyschtick blog covered it on March 21, one day before WUWT:
REPLY: I bow to the leader, thank you for pointing it out – Anthony


izen says:
March 27, 2012 at 7:54 am
“Global, but not synchronous.”
You mean YAD061 only recorded temperatures in Yamal?


I think it’s very good that the Daily Mail went with the story. At least this way a much wider audience will see the other side, which doesn’t happen a lot.

A. Scott

That’s what happens when WUWT is so far ahead of the pack on breaking news 😉

Kelvin Vaughan

No! 98% of climate scientists can’t be wrong!
Could they?

You make a statement and you bring up some worries. Nothing you stated invalidates the article yet you imply it’s bad science. What are you expecting? Just exactly what should those scientists should have stated to ally your fear?
From your implications, it seems you assume the scientists didn’t validate the reliability of their core? Normally, I’d assume the scientists involved would have searched and verified before using cores. Of course, after the CAGW alarmist scientists use of cores, you do have a concern. But there we have a difference, as I do not consider the alarmists scientists when they use inappropiate or invalid(ed) cores. But I can see where alarmists think every scientists uses bad data to make their points and lack of medieval warming period statements and graphs.
Still, you have to prove their cores are contaminated if you want us to believe it. That science statement; “scientific claims require proof, extraordinary scientific claims require extraordinary proofs”. The above paper easily meets the first part of that demand and since a MWP was accepted science for decades, that is enough. The anti-MWP people are the ones who must provide extraordinary proof.
Anyone got the stomach to read the main anti-MWP guy’s tweets and let us know any funny ones about the research article above?


seriously doubt the mental processes of those involved says:
March 27, 2012 at 8:50 am
Pardon me for being a very stupid, totally no climate science ordinary person, but my problem with the issue called “global warming” is the word global. I have no trouble with the idea that climate changes, but I do have a problem with the, in my opinion utterly stupid idea, that it changes all over the globe in the same direction at the same time.
All our incoming energy is from the sun and the earth’s orbit isn’t anything like constant.
With this in mind is it surprising that we have periods when things globally are a wee bit warmer, or a wee bit cooler?

More Soylent Green!

izen says:
March 27, 2012 at 7:54 am
Global, but not synchronous.

You mean like today, with some glaciers growing while many are shrinking? Or like the Arctic and Antarctic? Oops, scratch that — the Arctic ice cap is doing very well this year.
But maybe you mean like how most of the USA had a warm, mild winter while global temps are down. Except that the global temps also include the USA, so maybe it’s foolish to expect every place in the world to have the same weather/climate variation at exactly the same time?

John F. Hultquist

The last I checked, Washington State was still part of the USA (the merits can be debated at a latter time). We’ve missed the warm spring that is being claimed. That’s okay, though, because flowers, trees, and vines tend to jump on those warm temperatures – only to freeze when the weather fluctuates. For example, after a few warms days in Cleveland, OH there was a 5 hour period of below freezing early on the 27th. Ouch!
For central Washington State temperature charts see the link below – see if you can pick out the warming:

Joachim Seifert

MWP global?
(1) This does not fit with the IPCC ocean flow models of Broecker and
Dalton: The “See-Saw” ocean flow: First, the gulf stream, as today, flows
toward North and warming the NH, followed then by a gulf stream flow
South into the Antarctis, warming the SH and leaving the NH cold..
[.therefore the scare by a reversal ocean flow towards the south, thus
putting Europe into glacial times]….
….For this reason the MWP can only be regional because we enjoy the
gulf stream now, and “since the gulf stream does not flow southbound..
.there cannot be a MWP in the Southern Hemisphere….and “a MWP cannot
be exist globally on the planet”…..
(2) A MWP global goes against the Hockey stick showing flat 1000 years
temps and the great warm regional European MWP temperatures must
therefore been offset by ADDITIONAL cold climate in other regions of the
planet….only additional cold is capable to keep the global temp hockeystick
horizontally straight….therefore no global MWP!
It seems that pure heretic research is being conducted nowadays….


realclimate wont touch this LOL


Doesn’t this show big support for Svensmark and cosmic rays as didn’t the Medieval Warming period match up darn near exactly with sunspot minimums ?!? Correct me if I’m wrong. Thx.

“And I have more graphs and information from the actual paper than the Daily Mail has.”
The tightwad at the daily wail won’t stump up the wonga for a subscription to sciencedirect. Obviously, doing actual research into the source material is below Journo’s these days.

Dante D. Leone

Really, I would think the vikings covered it first for otherwise they’d not settled on Greenland. Would the natives have thrived on Tazmania in the south or the northern Alaska, Canada and Siberia, even, otherwise?
What would be of more note would be if the equator got less livable or not during the global midieval warm period. Did the south pacific islands get less populated? The central Africa? The south West Indies? And so on and so forth, for those places, according to todays logic, ought to have gotten ever too hot and dry and what not.

Ian W

The news isn’t that the MWP was global. The news is that what had been an abstruse argument about the shaft of the hockey stick, that causes eyes to glaze over with ‘ordinary people in the street’, has suddenly made prime time. Make no mistake this is hurting ‘the Team’ – now whenever they say ‘the current warming is unprecedented’ even ‘the man in the street’ starts to argue back.

Weird science program called ‘Global Weirding’, invented in the West Texas but promoted among others Mike Lockwood. It’s all down to UV apparently melting the Arctic Ice and freezing river Thames during Maunder Minimum. It’s a new chapter of the climate ‘Science Weirding’.
This was posted in another thread by mistake.


seriously doubt the mental processes of those involved says:
“Pardon me for being a very stupid, totally no climate science ordinary person, but my problem with the issue called “global warming” is the word global.”
It is quite easy really. If part of the earth’s surface warms then that increases the average temperature of the planet. That is Catastrophic Anthrpogenic Global Warming.
Alternatively, if part of the earth’s surface cools then that is a local weather event and can be ignored.


“Mother Nature may have spared Beaver Run alligator”

Apparently, there are other people out there besides me who do not know how to use the Scroll Bar.

Claude Harvey

Re: MangoChutney says:
March 27, 2012 at 7:59 am
“And Mann just happened to pick the only trees where the MWP didn’t occur – what are the odds”
Actually, as I understand various accounts of Mann’s performance it appears he picked through thousands of trees until he found a half-dozen or so that had been subjected to exactly the right combination of temperature, precipitation, sunlight, shade, bear poop and moose urine to produce the tree-ring pattern he was looking for. Unfortunately, those tree ring records showed temperatures heading south late in the modern record where actual temperatures were known to be heading north. So he used those tree-rings to eliminate the Medieval Warm Period and up to the point in time where they quit telling him what he wanted to see. Then he quit using tree-rings and stitched in recent actual temperatures (without telling us) to produce the infamous “hockey stick”.
If I missed some redeeming explanation for what Mann reputedly did or if the above account is not at least essentially correct, I’d appreciate someone enlightening me.

richard verney

I am not sure whether commentators have made the point but as I see matters, the importance of the publication in the Daily Mail is not what the research paper may say about the extent of the MWP but rather that the Daily Mail gets to a wide audience base.
WUWT is popular and gets many hits but most of those are by people who are already sceptical or at the very least are at the stage where they themselves would like to dig more into the subject. Those who frequently log onto WUWT will already know that the claim that the MWP was a limited Northern European phenomena is not based on sound science and that there is a body of evidence suggesting that it was a global event.
The Dailt Mail is read by many who may not be skeptical of AGW and reading that article may now lead them to start asking questions, to start becoming sceptical. It helpd chip away at the public perception of AGW and in turn the political stance on green policies and subsidies.
The more that MSM is willing to report on research that goes against or questions the AGW mantra, the quicker we will be able to shake off the shackles of this green madness for the benefit of all..

will gray

Found this and WOW.
Subsequently, those relatively warm water masses have been slowly transported by the deep oceanic circulation toward the Southern Ocean until they reached again the surface, contributing to maintain warm conditions in the Southern Hemisphere during the 13th, 14th and 15th centuries.
[Reply: Bad link, please repost. ~dbs, mod.]


izen: “Global, but not synchronous”.
What makes you think the margin of error for dating the various proxies doesn’t cover that?
If you take two identical sine waves that are occurring synchronously, and mistakenly get them 50% off from each other in time, then average them together, what do you end up with? A straight line.
As an explanation, that makes a heckuva lot more sense than the theorized “geographically alternating rolling warming period” that your crowd is trying to sell. Was there a giant ball of flame that took an extended walk-about around the planet for a couple hundred years?


Dr. Lu: “The reporter of that Daily Mail article published it anyway, after we told him the angel(sic) that he chose misrepresents our work.“


They just can’t get over the literal historic warming of the MWP, or the cooling of the LIA.
They can’t get over it, or they don’t want to get over it. Doesn’t matter.
Does it really matter if the sum of the game was warming or cooling in a non-uniform manner, or whether it was uniform across the globe, when it comes to calling it a Warm Period of Cold Period?
No. It only matters if one is seeking a means to justify fudging data or rewriting history.
Perpetual Modeling with improved data modifying formulas. Salted to taste.

Timbo says:
March 27, 2012 at 11:12 am

I think it’s very good that the Daily Mail went with the story. At least this way a much wider audience will see the other side, which doesn’t happen a lot.

OTOH, it shows that many WUWT readers read the Daily Mail. 🙂