Jo Nova finds the Medieval Warm Period

From Jo Nova a look at how the MWP looks when other data is used, not just a few trees in Yamal.

These maps and graphs make it clear just how brazen the fraud of the Hockey Stick is.

World Map of temperatures and studies showing warming

Click to enlarge

It’s clear that the world was warmer during medieval times. Marked on the map are study after study (all peer-reviewed) from all around the world with results of temperatures from the medieval time compared to today. These use ice cores, stalagmites, sediments, and isotopes. They agree with 6,144 boreholes around the world which found that temperatures were about 0.5°C warmer world wide.

Huang et al Boreholes graph of world temperatures

Bishop Pachuri of the IPCC and his wind powered staff

What follows is a sordid tale of a graph that overthrew decades of work, conveniently fitted the climate models, and was lauded triumphantly in glossy publication after publication. But then it was crushed when an unpaid analyst stripped it bare. It had been published in the highest most prestigious journal, Nature, but no one had checked it before or after it was spread far and wide. Not Nature, not the IPCC, not any other climate researcher.

In 1995 everyone agreed the world was warmer in medieval times, but CO2 was low then and that didn’t fit with climate models. In 1998, suddenly Michael Mann ignored the other studies and produced a graph that scared the world — tree rings show the “1990’s was the hottest decade for a thousand years”. Now temperatures exactly “fit” the rise in carbon! The IPCC used the graph all over their 2001 report. Government departments copied it. The media told everyone.

But Steven McIntyre was suspicious. He wanted to verify it, yet Mann repeatedly refused to provide his data or methods — normally a basic requirement of any scientific paper. It took legal action to get the information that should have been freely available. Within days McIntyre showed that the statistics were so flawed that you could feed in random data, and still make the same hockey stick shape nine times out of ten. Mann had left out some tree rings he said he’d included. If someone did a graph like this in a stock prospectus, they would be jailed.

GRAPH: Mann's Hockey stick graph wiped out the midieval warm period with statistical trickery.

Astonishingly, Nature refused to publish the correction. It was published elsewhere, and backed up by the Wegman Report, an independent committee of statistical experts.

GRAPH: Briffa's reconstruction was affected by one freak tree.

In 2009 McIntyre did it again with Briffa’s Hockey Stick. After asking and waiting three years for the data, it took just three days to expose it too as baseless. For nine years Briffa had concealed that he only had 12 trees in the sample from 1990 onwards, and that one freakish tree virtually transformed the graph. When McIntyre graphed another 34 trees from the same region of Russia, there was no Hockey Stick.

The sharp upward swing of the graph was due to one single tree in Yamal.

Skeptical scientists have literally hundreds of samples. Unskeptical scientists have one tree in Yamal, and a few flawed bristlecones…

Climate models don’t know why it was warmer 800 years ago.

The models are wrong.

The so-called “expert review” is meaningless. The IPCC say 2,500 experts review their reports, but those same “experts” made the baseless Hockey Stick graph their logo in 2001.

Craig Loehle used 18 proxies to graph the last 2000 years.

Craig Loehle used 18 other proxies. Temperatures were higher 1000 years ago, & cooler 300 years ago. We started warming long before cars and powerstations were invented. There’s little correlation with CO2 levels.

Sources: Loehle 2007, Haung and Pollack 1997, See for all the other peer reviewed studies to go with every orange dot on the map.  McIntyre & McKitrick 2003 and 2005, and update, Mann et al 1998, Briffa 2006, read McIntyre at, see “ClimateGate”, and  Monckton “What Hockey Stick” (Science and Public Policy Institute paper)

This is Page 8 & 9 The Skeptics Handbook II. 20 page PDF

I know a similar graph went up a couple of days ago around the web. The skeptics Handbook II was published on Friday Nov 20.

ACKNOWLEDGEMENTS: Thanks to Craig Idso of for his fabulous collation of research and his Medieval Warming Project which is an excellent resource, try the animated map!  A big thank you to John N for his work in helping to create the map.

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Seriously…it is beyond ridiculous how bad the science has been in this field the last two decades. 🙁


Bet you won’t find this debated at Copenhagen or reported on the BBC or Sky.
Is that because the science is proven and we only have, er, twenty or is it ten days to save the world?

Jean Meeus

I don’t believe in AGW, but I have a question about the graph “The real shape of the last 2000 years”. That drawing shows that during the Medieval Warm Period the mean global temperature was only about 0.5 °C warmer than now, and the Little Ice Age only 0.5 °C cooler than now.
Can half a degree centigrade have such an influence on the climate? You can hardly feel such a very slight temperature difference!

William Bowie

A great short summary that is something that canbe given to those currently bemused by the conflict between the science and Goreism. Thank you.


Well that’s thrown a falx in the works…..

Rhys Jaggar

I understand from reading your blogs some months ago that other researchers were trying to piece together reports from the UK navy over a few centuries to determine the extent of ice around the world, particularly at the entry to the NW passage.
Has that been completed yet as its answers might prove most informative at this epochal time…..?


Now the “tone” on CNBC has completely changed, skeptics are coming out of the woodwork! ClimateChange is now referred to as a “theory”. I wonder if this has anything to do with the fact that NBC/MSNBC/CNBC is no longer owned by GE?

Gösta Oscarsson

I have waited for this article for two years. I have in parallel studied WUWT and Co2 Science, and what they have refered has been the ultimate argument against Mann-made anihilation of the Medieval Warm Period. Well good that this finally reaches the 100.000 readers of WUWT today.
I have in vain recommended journalists of the Mainstream Media in Sweden to interview the scientific foot soldiers, doing this type of research in Scandinavia. No interest. I have also contacted some of the foot soldiers and asked why they do not speak up. Their answers made me think of McIntyres phrase “the silence of the lambs”.
Gösta Oscarsson


link to map wont work – –

Alexej Buergin

Switzerland is a very small country with a surprising number of daily newspapers, but not one good one amongst them. The voters have decided – in another matter – to completely disregard them. They “inform” about the MWP like this:
There were settlements in Greenland. The arctic sea was almost ice-free. Farmer plant in places higher up. THERE ARE NO INDICATIONS that is was warmer than today.

An excellent summary of the Hockey stick fraud versus the MWP truth. I have a feeling that if the mercury thermometer had been invented in the year 1000AD instead of 1714 ( and in the depths of the LIA to compound the issue) we would not have the current climate panic.

Rhys Jaggar (04:30:02),
This might be what you’re looking for: click

Is there another multiproxy global reconstruction except Loehle 2007, not made by Team?

Besides his fantastic work on the MWP, I also want to thank Craig Idso for his fantastic compilation of peer-reviewed studies at his website that I used as part of my research,
450 Peer-Reviewed Papers Supporting Skepticism of “Man-Made” Global Warming
His epic 868 page report refuting global warming hysteria is available for free online,
Climate Change Reconsidered
Check it out!


A poster (Charlie) over on eureferendum just posted this:
“Gorgeous busty Maundy Minimum has bust out with news of her three[check data]-in-a-bed romp with top Climate Professor Jones. Maundy, 34-28-36 [originally 32-30-42], said: ‘Well, when he asked me to massage his figures, who was I to argue? I called on my friend Climey Gate [36-24-36 – check figues with MM], and she said she’d be happy to help.’ Prof Jones, said the girls, needed help with his ‘hockey stick’ – although Maudy claimed that all that was needed was a good puck. ‘We sure put the upcurve in his stick!’ giggled the voluptuous Maundy. ‘Although, come to think of it, things did grind to a premature halt. Last we saw of the foxy prof was as he ran from the hotel room, hiding his figure in a towel, mumbling about losing his hard drive and “hiding the decline”……’


The only climate catastrophe is in the minds of those in government that want to increase taxes to increase their importance. So far the MSM has not even twitched on this hoax that dwarfs Madoff’s efforts.


Really enlightening. All these graphs are for saving!

John Simpson

I Found This reference to wattsupwiththat in the hacked emails
(memo to tom wrigley) see 1254751382.txt
Briffa has already made a preliminary response and he failed to explain his selection procedure. Further, he refused to give up the data for several years, and was forced to do so only when he submitted to a journal that demanded data archiving and actually enforced the practice.
More significantly, Briffa’s analysis is irrelevant. Dendrochonology is a bankrupt
approach. They admit that they cannot distiguish causal elements contributing to tree
ring size. Further, they rely on recent temperature data by which to select recent tree
data (excluding other data) and then turn around and claim that the tree ring data
explains the recent temperature data. If you can give a principled and reasoned defense of Briffa (see the discussion on Watt’s website) then go for it. I’d be fascinated, as would a rather large number of others.

” Jean Meeus (04:26:21) :
I don’t believe in AGW, but I have a question about the graph “The real shape of the last 2000 years”. That drawing shows that during the Medieval Warm Period the mean global temperature was only about 0.5 °C warmer than now, and the Little Ice Age only 0.5 °C cooler than now.
Can half a degree centigrade have such an influence on the climate? You can hardly feel such a very slight temperature difference!

The reason is that the 0.5C is a smoothed average and over time this can impact glacier formation and sea level etc.

Jean Bosseler

At some point in the future, hopefully, we may all sit around and laugh about the dead moose (or some other slow release fertilizer) that almost changed the world.


Here’s another source for Medieval Warming & Little Ice Cooling graphs, confirming what JoNova’s work.

Charlie Barnes

‘All models are wrong – but some are useful’ ; this quote, I think, due to George Box (sometime of Madison-Wisconsin).
The usefulness of any model is usually dependent on the adequacy of the assumptions underlying it. Nobody associated with driving the global warming/climate change/carbon dioxide scenario and its ramifications seems to have thought this to be important.

A Wod

I notice that the widget showing the temperature anomaly has jumped from 0.28 to 0.5, which is getting close to the MWP.
The BBC did mention the Climategate scandal on the radio 4 Today programme. There is going to be another radio programme called ‘the Report’ discussing the issue some time in the coming days. They said that the the blogosphere is awash with Climategate and that it will be difficult to persuade the US senate to ratify what Obama has signed up to.

Bruce Cobb

It’s not only dead, Jim, it’s annihilated, gone, it has ceased to be.
Here lies the Hockey Stick. Rest in pieces.


3×2 (05:09:29) :
At some point in the future, hopefully, we may all sit around and laugh about the dead moose (or some other slow release fertilizer) that almost changed the world.
Yes that is funny. However, centralized power is not. Let us be glad for every hindrance to the power of would-be tyrants.


Gregg E. (04:21:09) :
Has anyone done a study on CO2 absorption into ice, from air bubbles trapped in the ice? (….)

Not suggesting he is right or wrong (or even in/out the ball park) but he certainly has something to say on the subject. I would suggest that his “credentials” should not be taken lightly.

Roger Knights

Regarding the hockey stick, here’s Monckton’s long paper describing the shenanigans behind protecting it from criticism and “verifying” it, followed (pages 16-29) by summaries of 21 published papers that provide evidence of warming during the MWP. (Ten papers deal with Europe and the North Atlantic, eleven scientific papers address the period elsewhere on the planet.) Each summary occupies about half a page and contains a graph that illustrates key data points.

But none of this will even be revealed at Copenhagen. The fraud will be perpetuated because too much money now rides on continuing the fraud!

Jean Meeus (04:26:21) :

Can half a degree centigrade have such an influence on the climate? You can hardly feel such a very slight temperature difference!

The key is that it applies over the entire year(s).
Here are a few examples:
If you integrate that 0.5°C over the course of a heating season, it turns into a measurable amount of fuel use.
Imagine a mountain with a glacier and an environment with very little variability in the weather. Now decrease the temperature throughout the year by 0.5°C. The glacier terminus will move downhill some amount. A first order estimate might be to reach a point where the annual average is the same as it was before. The adiabatic lapse rate is, umm 1°F per 200 feet, so call it 1°C per 100 meters, so the terminus will be 50 m lower than before. If the pitch isn’t very steep, this could be a few hundred meters.
If you look at the length of the growing season (defined as the date of last frost to the date of first frost), then take the average temperature curve over the season and shift it down by 0.5°C you’ll see that the length of the growing season has gotten a few days shorter. Not only that, but the number of “growing degree days” has gone down. (GDD is a function of species and other stuff, but the sum will go down.) This caught some corn growers in the American midwest – they bought seed expecting that global warming would give them a long enough season. Didn’t work out.


ONE international is sending emails all over the web. once you click the link in the invitation, you sign their petition. you can sign as many times as you want by just clicking, which i find to be in bad taste.
for more info visit
and pls write about this ongoing unfair effort. thanks

Michael Mann attacks AGW goalie Phil Jones for letting the deniers hockey puck cross goal line–florida-player-slashes-his-own-goalie-in-the-head


All of this makes my blood absolutely boil! I know so many people who are totally ignorant of all this and Climategate, because they get their information from the mainstream “news”. And many of those same people are blind supporters of AGW. It’s time for me to take some action.

“Jo Nova finds the MWP.”
I didn’t know it was missing !!


Back2Bat (05:35:50) :
Yes that is funny. However, centralized power is not. Let us be glad for every hindrance to the power of would-be tyrants.

While I agree with the sentiment I have to say that while we argue the “toss” over 0.x°C warming or “climategate” Copenhagen will take place and agreement will be reached. Copenhagen is nothing to do with “Global Warming” it is about thieves agreeing how divide up the proceeds from “Carbon Trading”. It is without doubt the largest robbery in human history and everyone wants their cut.
Post Copenhagen there will be a new world reality. Everything you do, post Copenhagen, will be taxed. It will be a universal tax set at a level “decided” by “the market”.
As you can see the “market” consists of the same rent seekers that caused the last bubble and bale out. They just can’t stop themselves.
What makes me laugh most about all this is that the wind up toys that have been used so effectively are about to see reality. Watch them squirm. Hansen is right,
if the real object were ever a reduction in consumption your Government would have simply levied a 15% tax on your utility bills. The real object is a tithe on your labour that goes straight to the bottom line of monoliths such as Goldman Sachs. They are on the Copenhagen runway waiting to re-fuel the next bubble. Follow the money (and your extra hours at work).
This is all so far beyond robbery that new words will be required to describe it. Even if temperatures dropped back to 1970’s levels tomorrow morning this train will not be stopped. All the conspiracy theories (on both sides) are just that. You really don’t need a formal conspiracy when I offer you a reasonable share of a Trillion dollar pot of money from fresh air. Your answer is .. sign me up.


Jo Nova
With reference to the Loehle 2007 paper, this was supplemented and superseded by Loehle and J.H. McCulloch 2008 ( )
These papers collate 18 other studies which do NOT contain tree ring data to obtain a graph of global temperatures for the last two thousand years.
Let’s take Loehle and McCulloch’s 2008 as it is and see what it tells us.
Their results of the 2008 paper do NOT show what you claim, ie, that ‘Temperatures were higher 1000 years ago’, nor do they make that claim. The reason is that their graph that you reproduce does not end ‘today’ as you have labelled it.
Their proxy results END with the 29 year average temperature for 1935 (ie the average from 1921 to 1949 inclusive, of which 1935 is the mid-point). Loehle states, “Accordingly, the corrected estimates only run from 16 AD to 1935
AD, rather than to 1980 as in Loehle (2007).” What you have labelled as ‘Today’ in the Loehle graph corresponds to 1935.
Since the proxy data ends in 1935 Loehle then, quite reasonably, looks at the latest (for him) 29 year average which is centred on 1992 (ie from 1978-2006) and finds (correctly) that that period was +0.341C above the 1935 average (using GISS Land+ocean) and 0.07C BELOW the highest peak of the Medieval Warm Period.
So, according to Loehle 2008, the 29 year average global temperature centred on 1992 was marginally (indeed insignificantly) below the MWP peak by 0.07C.
However, 1992 is not ‘Today’ either. If we wish to see how ‘Today’s’ temperatures compare with the peak of the MWP, (according to Loehle and his use of non-tree-ring proxies), then we can get an indication by taking five year averages to smooth values to see how temperatures have changed since 1992. We find that 2006 (the latest year for which a five year average can be taken) is 0.29C above 1992 (five year GISS anomaly 1992=+0.24C, 2006=+0.53C). Therefore, ‘Today’ (or as close to today as we can reasonably get) is 0.22C ABOVE the highest peak of the MWP, based on the data in Loehle 2008. [Of course, in order to make that point conclusively, we would need the 29 year global average centred on 2006, but we won’t get that until after 2200.]
Thus, present temperatures are +0.22C ABOVE the peak of the Medieval Warm Period, based on information from the author you chose, Loehle, who used non-tree-ring proxies for his source..
Why did you not report this, rather than show your readers a graph that leaves them with the impression that ‘Today’s’ global average temperatures are about 0.3C below that of the MWP peak?

Douglas DC

That widget jump is due to El Nino building-in November the .5 for the MWP is the average,BTW we are heading for Near zero F lows here in NE Oregon with snow on the


Another excellent post, very didactic, simple and comprehensible by everyone. This will work also for the msm.


Back2Bat (05:35:50)
“Yes that is funny. However, centralized power is not. Let us be glad for every hindrance to the power of would-be tyrants”
However the CLIMATEGATE leakage proves that there is an internal division (or call it ambition) among those who allucinate themselves as future world tyrants.


Once people realise that this is a new universal tax with no escape route I’m sure this country (UK) will react (turn volume down) in much the same way it always has. Especially once people realise where the “tax” is actually going.

A Wod

Slioch wrote:
Thus, present temperatures are +0.22C ABOVE the peak of the Medieval Warm Period, based on information from the author you chose, Loehle, who used non-tree-ring proxies for his source..
Why does Loehle decide to use corrected smoothed data? Steve Mcintyre has shown that if you start to smooth data then you miss out important anomalies, like smoothing out the way a drunken person walks, which hides the fact that they are drunk.

Don B

But the “true believers” will not give up. Johann Hari actually writes that hundreds of thousands of scientists have independently reached the conclusion that burning fossil fuels will have terrible consequences. You will not believe what else he writes…

Don B

On page 3 of Jasper Kirkby’s report explaining the justification for CERN conducting experiments to test Henrik Svensmark’s theories linking solar activity, cosmic rays, clouds and climate, are graphs of various proxies showing the MWP and the LIA.

Don B

Oops. I forgot to mention that the CERN graph of temperature proxies also shows Mann’s hockey stick for comparison; Kirkby mocks the hockey stick, in the understated academic way.


Wait a minute…
Craig Loehle’s reconstruction shows the MWP centered around AD 950 and down to 0C by AD 1250. McIntyre’s reconstruction shows the MWP as warm as +0.5C around 1400. There must be some uncertainty in those reconstructions. Oh, there it is in the error bars of the Mann et al reconstruction.
If I remember right, Loehle also used 30 year averages with data ending around 1950. The warming since the mid-century is basically excluded from Loehle’s reconstruction. If you are comparing the MWP to the early part of the century (before significant AGW), then why are you calling it “today”?
The boreholes seem to match McIntyre’s reconstruction but not Loehle’s. I believe they also have a very coarse resolution in time and can’t resolve changes over less than about 50 years. That means they also exclude the warming of the last few decades.

Henry chance

Houston this morning broke a record with the earliest snowfall ever recorded in the city’s history.
this is reported by the MSM.
December on track to be coldest December evah. Poor Houston.


Don B (07:12:03) :
Nice catch. Like I said “wind up toys”.
Falling Arctic ice shelves, of countries being swallowed by the sea, of vicious wars for the water and land that remains.
Is he planning a new Sci-fi series? Does the Arctic have ice shelves (being an Ocean)?
It is a good thing in the end that these people exist and get exposure. How else will “regular folk” come to see them for the eco-loons they really are.


Check out the chart of the temperature cycle here:
It supports the cyclical temperature graph shown above.


Guys…lets not ‘Do A Phil’ here…….Sliochs comment, if true, blows this whole thread out of the water.
Look…my own view is that AGW is more political sham than real, but, I’m not going to stick fingers in my ears when one on ‘our side’ presents a graph that is pulled down so easily by the ‘other side’.
Crowing about Jo Nova graph – if it is indeed dodgy – makes us look silly, and would be the cause of sarcastic emails at CRU yes?
Soooooooooo…..can someone come back on Sliochs points, or is that poster correct….Craig, are you lurking?