More evidence that the Medieval Warming Period was global, not regional

From the “we have to get rid of the Medieval Warming Period” department. Even though this paper was published in late 2017, it was recently highlighted in EoS, as shown below. Michael Mann, and others, in their zeal to cover up warming periods of the past, to make it look like his hockey stick is “unprecedented”, won’t like this paper. They also won’t like this map showing over 1000 studies and their results:

Climate reconstructions of the ‘Medieval Warm Period’ 1000-1200 AD. Legend: MWP was warm (red), cold (blue), dry (yellow), wet

From EoS:

Medieval Temperature Trends in Africa and Arabia

A synthesis of paleotemperature reconstructions from published case studies suggests warm onshore temperatures persisted across most of Afro-Arabia between 1000 and 1200 CE.

The Sahara in southeast Libya. The medieval land temperature history is still poorly known in large parts of Africa and Arabia, emphasizing the need for a systematic paleoclimatological research program. Credit: © Karsten Battermann

Reconstructions of Northern Hemisphere temperatures have repeatedly indicated the Afro-Arabian region experienced climate perturbations, including an extended period of anomalously warm conditions, during medieval times. Because this Medieval Climate Anomaly represents the closest analogue to modern warming, it defines a crucial baseline by which modern postindustrial climate trends can be compared.Although the Medieval Climate Anomaly has also been documented in other parts of the world, its occurrence on the Arabian Peninsula and the African continent, which together comprise about one quarter of Earth’s landmass, is less certain.
This is due to the lack of high-quality proxy records, such as ice cores and tree rings, in the region. To help fill this gap, Lüning et al. correlated and synthesized the findings of 44 published paleotemperature case studies from across the region and mapped the resulting trends of the anomaly’s central period, which lasted from about 1000 to 1200 CE.

A comprehensive review of paleotemperature reconstructions paints a picture of warm onshore temperatures across Afro-Arabia between 1000 and 1200 AD.
To better characterize temperature fluctuations in Africa and Arabia during medieval times, researchers synthesized paleotemperature records from across the region, including the Tanzanian portion of Lake Tanganyika (pictured here). A core from this lake represents one of the few medieval paleotemperature reconstructions that are available from the East Africa Rift. Credit: Andreas31, CC BY-SA 3.0

The results indicate that the majority of onshore Afro-Arabian sites experienced warming during the Medieval Climate Anomaly. The one exception was the southern Levant, which endured a cold phase during the same interval. From offshore records, the team also documented cooling in locations that currently experience cold-water upwellings but generally warmer conditions away from these upwelling zones during the same period.

AT AMAZON, save on Flashlights. You can never have too many. A lantern or two is nice to have as well, for power outages.

In some records, the researchers noted the presence of obvious cold spikes during intervals corresponding to decreased solar activity or declining ocean cycles. This, they argue, suggests that solar forcing and changing ocean circulation are the most likely causes of medieval era climate change.

This study represents a step toward globally characterizing the Medieval Climate Anomaly, an improved understanding of which will help scientists refine global climate models and improve hindcasting. To date, however, very few paleotemperature data exist from Afro-Arabia; the authors note that all of West Africa is currently represented by a single data point. Systematic research will be necessary to adequately reconstruct medieval paleotemperature patterns and their causes across this vast region. (Paleoceanography and Paleoclimatology, 2017)

Warming and Cooling: The Medieval Climate Anomaly in Africa and Arabia

Sebastian Lüning, Mariusz Gałka, Fritz Vahrenholt


The Medieval Climate Anomaly (MCA) is a well-recognized climate perturbation in many parts of the world, with a core period of 1000–1200 Common Era. Here we present a palaeotemperature synthesis for the MCA in Africa and Arabia, based on 44 published localities. The data sets have been thoroughly correlated and the MCA trends palaeoclimatologically mapped. The vast majority of available Afro-Arabian onshore sites suggest a warm MCA, with the exception of the southern Levant where the MCA appears to have been cold. MCA cooling has also been documented in many segments of the circum-Africa-Arabian upwelling systems, as a result of changes in the wind systems which were leading to an intensification of cold water upwelling. Offshore cores from outside upwelling systems mostly show warm MCA conditions. The most likely key drivers of the observed medieval climate change are solar forcing and ocean cycles. Conspicuous cold spikes during the earliest and latest MCA may help to discriminate between solar (Oort Minimum) and ocean cycle (Atlantic Multidecadal Oscillation, AMO) influence. Compared to its large share of nearly one quarter of the world’s landmass, data from Africa and Arabia are significantly underrepresented in global temperature reconstructions of the past 2,000 years. Onshore data are still absent for most regions in Africa and Arabia, except for regional data clusters in Morocco, South Africa, the East African Rift, and the Levant coast. In order to reconstruct land palaeotemperatures more robustly over Africa and Arabia, a systematic research program is needed.


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Curious George

Why are they using data and not models?


And unadjusted data at that obviously.
Very unprofessional.

Tom Gelsthorpe

Data is nowhere as good st frightening the horses. How could they!


It irks me that there is a need to prove the MWP because it interferes with the AGW narrative.

We’ve been down this MWP road before – see the 2003 paper by Soon and Baliunas, discussed below.
Warmists hate the MWP, because it adequately disproves their false alarmist nonsense.
Regards, Allan
The following history on the subject of the MWP may be of interest – I wrote this article for E&E in 2005.
Willie Soon has managed to hang on despite many attacks, but my friend and co-author Sallie Baliunas was driven from Harvard-Smithsonian, reportedly through the actions of John Holdren, now Obama’s Chief Scientific Advisor.
I suggest that the conduct of people like Holdren and those who collaborated with them should be thoroughly investigated by the new Trump administration.
Regards, Allan
The global warming debate heats up
by Allan M. R. MacRae
Energy and Environment, Feb 2005
In the April 2003 issue of Energy and Environment, Willie Soon and Sallie Baliunas of the Harvard-Smithsonian Center for Astrophysics and co-authors wrote a review of over 250 research papers that concluded that the Medieval Warm Period and Little Ice Age were true climatic anomalies with world-wide imprints – contradicting Mann’s hockey stick and undermining the basis of Kyoto. Soon et al were then attacked in EOS, the journal of the American Geophysical Union.

In both cases, the attacks were unprofessional – first, these critiques should have been launched in the journals that published the original papers, not in EOS. Also, the victims of these attacks were not given advanced notice, nor were they were given the opportunity to respond in the same issue. In both cases the victims had to wait months for their rebuttals to be published, while the specious attacks were circulated by the pro-Kyoto camp.


They criticize studies like this based on the warming not being “contemporaneous across the globe”.
Of course, whether or not warming is “contemporaneous enough” is subjective, so they can pick and choose what studies to accept or reject.
They also feel no pressure to prove that current warming is “contemporaneous across the globe”, when looking at any global temperature map makes it obvious that it clearly is not, and we see brief and even somewhat persistent cooling in different locations.

A C Osborn


AGW is not Science


Robert in Busan


Ron Long

Looks like this report broke his hockey schtick. Maybe he will sue?

Tom Halla

Poor Mikey!

Manntastic! Without data you only have opinions, and his data is no longer worth the paper it is presented in. Is Scott Pruit lurking here? Hope so.
The concatenated s craps of disparate time series , “adjusted” to make them join up and for the present look hottest with a tick on the end, arrogantly denies the reality on the ground our ancestors recorded as facts when there were no numbers, and even has the science denying front to refuse to explain how the numbers were adjusted when challenged, when the contrary evidence of ICE and AGRICULTURE was so very clear. Unless you are in the climate food chain this supports, how could you treat it as even probable? He has no credibility as a scientist at all, as he denies both its methods and the data with his baseless models.


Well of course the medieval warm period across the European continent would necessarily have to stop at the Mediterranean Sea because weather patterns are not allowed to cross the Mediterranean and effect Africa. It’s just not done. /sarc


The weather patterns gather in flotillas on Africa’s north coast, cross the Mediterranean & sneak onto Europe.


“From the “we have to get rid of the Medieval Warming Period” department”
So, what does the “sensitivity must be low” department have to say about it?

> Medieval Climate Anomaly (MCA) is a well-recognized climate perturbation…
Even the wording is biased. The period of warming was not anomalous. The warmists are constantly trying to hijack the language.

Quite right Rob
Most of the Holocene has been even warmer than the MWP
It was the LIA that was anomalously cold


It was called Medieval Climate Optimum when I was in college in the early 1970s. Then it transitioned to Medieval Warm Period, and now it has been renamed the Medieval Climate Anomaly.
I wonder how they have silenced the historians, economists, and archaeologists in academia.


I wonder how they have silenced the historians, economists, and archaeologists in academia.
They were body-snatched & replaced w/plant-based, marxist replicates.

… next, The Medieval Alien-Death-Ray Episode
After that, your guess is as good as mine.


Next, Dark Ages Warm Catastrophe.
When you cannot deny it happened, just show how horrible it was. Somehow cause the black Death, for sure. Just remember the endless list ill effect of current warming: not that hard to do the same for previous time.


We have recorded history. We know that the MWP in Europe, Iceland, and Greenland existed because certain crops could reliably be grown that could not reliably be grown during the later LIA. Yesterday we had similar evidence in a WUWT story about China.
It’s not that the temperature was warm at all times and in all places. There were cold periods during the MWP. They would have caused occasional crop failures. The point is that the climate was sufficiently reliable that farmers would continue to plant certain crops. All this is part of written history.
Dr. Michael Mann can mess with the science all he wants but he is still thwarted by written history. When Mann tried to wipe out the MWP, I went with the written record and became a skeptic. Thanks Mike.

Ross King

Commiebob….. in turning you into a skeptic, The Mannipulator has performed ONE useful function!

John harmsworth

Yup1 Once one clearly identifies a liar, one also wonders why they lie and what else they lie about. It makes s clear path to the truth from various dark places.
Thanks Mike indeed! Keep lying, it makes easier work on where to look for truth.

AGW is not Science

The ridiculous notion that a period when you could farm on Greenland in a place that is currently buried (along with the graves of the once-farmers) under “permafrost” was warmth somehow miraculously confined to only a portion of the globe, as if divided by a glass dome from the rest, is about as credible as the whole AGW meme.


So you don’t accept what this paper says then?

Ted Midd

Such as?


Being of Northern European Stock (aka Viking) Mann, et al should just study Viking history. They didn’t go a viking with a climate conducive to their adventures. I will bet Mann doesn’t have a clue how far afield from Scandinavia the Norse traveled during the MWP.

Louis Hooffstetter

Michael Mann is from Viking stock!?!?!
What would his Viking name be?
Gudrun of the tree rings? Audhild-fighting for wealth?
Eric the Red and Leif Eriksson are rolling in their graves!


Two observations:
1.) 1000 studies document warming, 20 cooling…. This demonstrates the need that the 20 cooling need to be re-done, because of shoddy work, see the next point:
2.) “Levant” and “off-shore”: We talk about marine, underwater values in coral –
50 – 100 m water depth. Underwater temp proxies do not resemble true atmospheric temperatures, are late and slow in change…the B.Bereiter paper (at WUWT 4.Jan) “Mean global temps during the last glacial transition” shows for example, that global warming of the past 50 years is about 0.1°C (with underwater data), and we all know that atmospheric warming was much higher…. The use of off-shore, underwater data is the perfect way of hiding
atmospheric warming periods….. The Marcott and Shakun 2013 study on
“A reconstruction of regional and global temperature for the past 11,300 years”
did their statistical tricks using 80% marine archives and median 120 year sampling” ….. It is regrettable, that for sake of completeness, misleading studies also appear together as equal to sound scientific work. .

Pat Frank

Assigning temperatures to proxies already departs from science.
None of them are based in a physical theory converting proxy metrics to degrees Kelvin.
At very best, a good proxy will presently produce only estimates of a warmer/wetter or cooler/drier climate. Never temperatures.

John harmsworth

Au contraire! Michael Mann can pick out a single tree to sample and tell us the entire temperature history of the world!
Even with his eyes shut!

Bob Stewart

John, alas, Mann has yet to find that specific tree. His Nobel Prize awaits the discovery if it hasn’t been turned into plywood. And Pat Frank, thank you for your eye opening work demonstrating that all those elaborately complicated, but yet hopelessly inadequate, climate models are in principle nothing more complicated that a simple regression on CO2. The last decade has conclusively demonstrated that their hypothesis has been disproven. But the hypothesis is the essential element from a political standpoint, and so it blunders on, kept aloft with Science Guy science.


Plywood is even better. Made of a number of trees from you don’t know where, that is, representative of all trees.
I just happen to have a perfect piece of furniture, from which Mann will easily draw a map and time line of all Earth temperature in the future century


“Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact”
You know that any website that has to put the word “trustworthy” in it’s blurb is full of it. It’s like fair and balanced.

David Ball

More evidence that climate modellers haven’t a clue regarding the body of work and data in the field of climate science. If they had, there would have been research on their part to find evidence against their hypothesis, as per the scientific method. No?
Caution: Extremely rhetorical question.

Wight Mann

“a $y$tematic re$earch program i$ needed”

Bob Stewart

In a rational world, the Little Ice Age and the MWP would have been used as tests of Mann’s hypothesis that global temperatures in the distant past can be predicted by using surrogate historical data “trained” using modern temperature records. Since Mann’s predictions do not replicate these well documented events, his hypothesis has been proven wrong. It is ironic that this fundamental understanding of the scientific method has been overlooked by so many. We end up arguing about individual trees while overlooking the fact that they are in a forest.


On Judith Curry’s site a month or two ago JimD was trumpeting a cherry-picked (starting in the LIA) hockey stick created by the “Pages2k” Holocene reconstruction project. I cited this paper by Luning et al as part of abundant evidence that the MWP (MCA) was real, global and probably warmer than today. Africa and Arabia are a quarter of the earth’s land surface, so this confirmation of the MWP there is a big deal.

Dennis Stayer

I think that referring to the Medieval Warm Period as an “anomaly” is incorrect as it infers that there is a “normal” to be judged against. Sure, if we look at climate over short human generational time periods it may look like an anomaly, but If we look at the climate over geologic time periods we find that there is no “normal” to be judged against! What we find are swings between extremes, with cold extremes being more dominant than warm ones. That the concentration of CO2 in Earths atmosphere has little to no correlation to Earths temperature. The sad fact is that certain political and financially motivated “pseudo scientists” and politicians would like to eliminate the MWP, and probably the RWP and others to achieve their political and financial agenda, to the detriment of us all! Only the pursuit of science, as traditionally thought of, where a hypothesis is presented, tested and methods, data and techniques shared in the interest of falsification should be considered, anything else is just politics!

I’m no scientist to speak of, but when I read that the climate temperatures are the warmest now than they’ve been for about 133 years, I am not impressed. I think that time spans of 1,000 years should be used when talking about climate and not weather. as for temperatures during the little ice age, consider that the Thames River could be used as a road for horses and carriages. The total foot area for a 1,000 pound horse is about that for the two feet of a human. The ice had better be thick to support the traffic. John Minich


When I first became suspicious that we were being lied to about global warming as it was called 20 years ago the Medieval warm period and the Little Ice Age were dismissed and the Warmists tried to say that they were not global and they were a fantasy .
We still have many like Nick Stokes will not accept facts and keep denying that the Medieval Warm period ever happened and that it was warmer then than at present .
James Renwick and his partner in crime Jim Salinger of New Zealand and both former NIWA scientists involved in data tampering still strenuously push the warming meme even though Jim Salinger worked on a cave study of stalactites/in New Zealand that proved that it was warmer 1000 years ago than now .
Doug Edmeades a prominent skeptic or should I say realist writes for the New Zealand Farmer a free magazine delivered to all rural post boxes .
He has been told by the editor that they will not publish any more articles because they have had to much reaction to the truth that he has written about .
James Renwick who is now a university professor attacked Doug for stating the truth.
Renwick asserts that only two factors drive global temperature _the suns brightness and greenhouse gasses .
This is simplistic and this man teaches this at Victoria University in Wellington and he brought no proof whatsoever to the debate but the consensus and the IPCC
I saw Renwick write in the New Zealand Herald about 15 years ago that the MWP was an inconvenience to their theory and they had to prove that it did not occur globally

Dario from Turin (NW Italy)

maybe we should return to the old name of the MWP: “the Little Climate OPTIMUM”, that is the name the old, true climatologist used…. but someone still uses it….