More evidence the Medieval Warm Period was global

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

==============================================================

Ikaite is the mineral name for the hexahydrate of calcium carbonate, CaCO3·6H2O. It is only found in a metastable state, and decomposes rapidly once removed from near-freezing water. Image from Wikipedia - click for details

Oxygen 16/18 isotope ratios show the Medieval Warm Period was global – all the way to Antarctica

Despite this poorly written press release with the “topsy-turvy” first paragraph written by some PR person at Syracuse University who doesn’t even mention the name of the paper, there’s some interesting science in the paper once you figure out what the name of the paper is. Unfortunately, this is published by Elsevier, and like a growing number of people in the scientific community (8500+ now), I refuse to purchase anything from Elsevier (especially when they want $40 to read a paper already funded by taxpayers) since they pulled that stunt trying to lobby our legislature. Hopefully the authors themselves will liberate this important paper and put it on one of their own websites.  (Update: I’ve been in touch with Judy L. Holmes of Syracuse who has been very gracious. It seems Eurekalert botched the press release, excluding important info and that is now being corrected) – Anthony

Scientists use rare mineral to correlate past climate events in Europe, Antarctica

New study published in April issue of Earth and Planetary Science Letters

The first day of spring brought record high temperatures across the northern part of the United States, while much of the Southwest was digging out from a record-breaking spring snowstorm. The weather, it seems, has gone topsy-turvy. Are the phenomena related? Are climate changes in one part of the world felt half a world away?

To understand the present, scientists look for ways to unlock information about past climate hidden in the fossil record. A team of scientists led by Syracuse University geochemist Zunli Lu has found a new key in the form of ikaite, a rare mineral that forms in cold waters. Composed of calcium carbonate and water, ikaite crystals can be found off the coasts of Antarctica and Greenland.

“Ikaite is an icy version of limestone,” say Lu, assistant professor of earth sciences in SU’s College of Arts and Sciences. “The crystals are only stable under cold conditions and actually melt at room temperature.”

It turns out the water that holds the crystal structure together (called the hydration water) traps information about temperatures present when the crystals formed. This finding by Lu’s research team establishes, for the first time, ikaite as a reliable proxy for studying past climate conditions. The research was recently published online in the journal Earth and Planetary Science Letters and will appear in print on April 1. Lu conducted most of the experimental work for the study while a post-doctoral researcher at Oxford University. Data interpretation was done after he arrived at SU.

The scientists studied ikaite crystals from sediment cores drilled off the coast of Antarctica. The sediment layers were deposited over 2,000 years. The scientists were particularly interested in crystals found in layers deposited during the “Little Ice Age,” approximately 300 to 500 years ago, and during the “Medieval Warm Period,” approximately 500 to 1,000 years ago. Both climate events have been documented in Northern Europe, but studies have been inconclusive as to whether the conditions in Northern Europe extended to Antarctica.

Ikaite crystals incorporate ocean bottom water into their structure as they form. During cooling periods, when ice sheets are expanding, ocean bottom water accumulates heavy oxygen isotopes (oxygen 18). When glaciers melt, fresh water, enriched in light oxygen isotopes (oxygen 16), mixes with the bottom water. The scientists analyzed the ratio of the oxygen isotopes in the hydration water and in the calcium carbonate. They compared the results with climate conditions established in Northern Europe across a 2,000-year time frame. They found a direct correlation between the rise and fall of oxygen 18 in the crystals and the documented warming and cooling periods.

“We showed that the Northern European climate events influenced climate conditions in Antarctica,” Lu says. “More importantly, we are extremely happy to figure out how to get a climate signal out of this peculiar mineral. A new proxy is always welcome when studying past climate changes.”

 ###

An ikaite record of late Holocene climate at the Antarctic Peninsula

http://www.sciencedirect.com/science/article/pii/S0012821X12000659

Zunli Lu, Rosalind E.M. Rickaby, Hilary Kennedy, Paul Kennedy, Richard D. Pancost, Samuel Shaw, Alistair Lennie, Julia Wellner, John B. Anderson

Abstract

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.

UPDATE: A colleague has forwarded a copy of the paper, allowing me to cite some additional information that I have presented below:

Click to enlarge. Fig. 6. δ18Ohydra profile (in green) plotted with other climate records, assuming sedimentation rate of 0.96 cm/yr and ikaite formation depth of 3.04±0.57 m. δ18Ohydra variability among different crystals found at the same depth is about±0.33‰. A–B: Magnetic susceptibility and TOC of JPC2 are plotted against age. C: SST at Palmer Deep, the line represents a five-point moving average (Shevenell et al., 2011). D: δ18OEPICA data are smoothed by a ten-point moving average. E: Timing of climatic events summarized for the AP region and citations (1 — Pudsey and Evans (2001); 2 — Jones et al. (2000); 3 — Brachfeld et al. (2003); 4 — Khim et al. (2002); 5 — Hall et al. (2010); 6 — Domack et al. (1995); 7 — Liu et al. (2005)).

From the discussion section:

The MWP has not yet been unambiguously established around the

AP. Three δ18Ohydra values fall in this period and all of them are significantly

lighter than those values of older crystals by 2–3‰, a difference

too large to be explained by analytical uncertainties and

variability among crystals formed at the same time (0.33‰ at

JPC24), and are associated with lower δ18OCaCO3.We tentatively interpret

this shift in ikaite isotopic values as the result of meltwater invasion,

and warming in the Firth of Tay during the MWP. The ~5‰

decrease in δ18Ohydra at the beginning of the MWP must indicate

very strong freshening at the bottom of fjord, likely due to meltwater

cascading to depth. How such a distinct isotopic signal might be preserved

to such great depth in the fjord is beyond the scope of this

paper. However, meltwater beneath the ice-sheet is known to be

injected into fjords at different water depths including the base of

the fjord (Domack and Ishman, 1993). Although meltwater typically

mixes quickly with fjord water, it can be trapped at the base of the

inner fjord sometimes (e.g. when there is a sill preventing it from

moving forward) (Domack and Ishman, 1993). We hypothesize that

such subglacial meltwater may be the cause of strong meltwater signal

at the beginning of MWP. Other evidence supports the meltwater

signal inferred from δ18Ohydra. At the Firth of Tay, MS shifted to mostly

below average values between 1 and 0.6 ka (Fig. 6A). Low MS was

also found for the same period of time in Bransfield Strait sediments

and was considered to mark the MWP (Khim et al., 2002). Elemental

ratio records from Maxwell Bay, northern Bransfield Strait, allow

identification of both the MWP and the Little Ice Age (Monien et al.,

2011). Moss exposed by recent ice retreat on Anvers Island, West

AP, were radiocarbon dated to 0.7–0.97 ka, contrary to the much

older ages of reworked marine shells in the same sections, indicating

that the ice-sheet was reduced during that period to an extent of similar

magnitude to today (Hall et al., 2010). δ18OEPICA (Stenni et al.,

2006) shows warming at 0.6–0.8 ka, but with a brief cooling in between.

SST at Palmer Deep was even higher than modern during

this period (Shevenell et al., 2011). There is a notable lag between

the onset of MWP at the western AP and at the eastern AP according

to this SST record and our ikaite record although this observation

needs to be confirmed by additional records. On the eastern AP, no

significant change in foraminifera assemblage at Firth of Tay was observed

that could correspond with the Medieval Warm Period, Little

Ice Age, or the warming over the last century (Majewski and

Anderson, 2009). Also signals of the MWP or LIA, if any, were not

up to a magnitude that influenced glacial sedimentation

(Michalchuk et al., 2009).

Our most recent crystals suggest a warming relative to

the LIA in the last century, possibly as part of the regional recent

rapid warming, but this climatic signature is not yet as extreme in nature

as the MWP. 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.

Conclusions

We report the first comprehensive geochemical study on an

ikaite-containing core to demonstrate the potential of using hydration

water δ18Ohydra as a paleoenvironmental proxy. Porewater solute

concentrations indicate that these authigenic carbonate minerals

form in a narrow and shallow zone where Ca and DIC are both relatively

enriched. Coupling δ13C of ikaite crystals and δ13C of porewater

DIC, allows estimation of formation depth for individual crystal. The

ikaite formation depths are then used to calculate the time of crystallization

relative to the ambient sediments. δ18Ohydra and δ18OCaCO3

throughout JPC2 at Firth of Tay are reported. The youngest crystal

precipitated in modern porewater validates the fractionation factor

obtained in the previous study (Rickaby et al., 2006). The late Holocene

climate pattern inferred from δ18Ohydra and δ18OCaCO3 is comparable

to other records from the region and our ikaite record provides

new support that the MWP and LIA might have influenced the AP. In

the future, paired δ18Ohydra and δ18OCaCO3 may be used to calculate

δ18O of paleo-porewater indicating temperature changes. At this

stage, the geochemistry of ikaite serves as a qualitative, rather than

a quantitative, climatic proxy, because it remains challenging to account

for kinetic effects on uptake of δ18O into the carbonate during

crystallization and any post-crystallization exchange of δ18Ohydra

signal.

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David A

Sounds like a good addition to so many papers which support that the MWP was real, global and as warm or warmer then the current T. It is amazing that a few tree rings from a few, mostly NH locations, can be considered to outweigh a far more diverse selections of proxies, from thousands of locations.
To understand why the “team” is so desparate to destroy the MWP is crucial to the debate. In trying to support the “cause” they trapped themselves. They flatlined CO2 and temperatures for the one to two thousand year HS reconstructions. This allowed them to assign an artificially high weight to modern CO2 increases. They further increased the weight of CO2 by only considering solar influence on climate to be a lineal response to TSI changes, ignoring many other possbilties within the peer reviewed literature. They allowed these flawed studies to set the CO@ senstivity used in the models. Now, having flatlined CO2 for the period of the reconstuctions, if the MWP is shown to be real then their theory is destroyed, and their failed models are sent to the garbage pile. (What a tangled mess we weave…..)

Jeff Norman

The Antarctic Peninsula? That extends well north of the Antarctic Circle, and may as well be considered part of the North Atlantic.
Sure, just like the Arctic Archipelago, Sargasso Sea, Central America, the Western United States, Siberia and New Zealand. What in the world isn’t in Western Europe and the North Atlantic?

Jeff Norman

Oops, my “sarc” tags disappeared.

Because of the lack of accurate dating in Antarctic ice cores, correlation with the Greenland ice cores and with other Northern Hemisphere paleotemperature proxies has been uncertain. The land record in New Zealand shows a consistent paleotemperature record in lockstep with the NH, but correlation with Antarctica has remained a problem. This new research is therefore significant. If anyone gets a copy of the paper, I’d sure like to see it.

George V

“We showed that the Northern European climate events influenced climate conditions in Antarctica,” Lu says.
Do we know climate events in Antarctica didn’t influence climate conditions in Northern Europe?
George V.

NIce paper, but:
““We showed that the Northern European climate events influenced climate conditions in Antarctica,” Lu says.”
This is an ingenuous statement. The results show that the LIttle Ice Age was global, but NOT that events in Northern Europe affected the Antarctic. Whatever caused the events in Europe ALSO caused a cold phase in the Antarctic.
Correlation does NOT mean causation.

joe

Unfortunately, this is published by Elsevier, and like a growing number of people in the scientific community (8500+ now), I refuse to purchase anything from Elsevier (especially when they want $40 to read a paper already funded by taxpayers) since they pulled that stunt trying to lobby our legislature.
i found this interesting.

Doug Proctor

The qualifying remarks in this paper allow Mann et al to say that there is no solid evidence from this study. The authors show a concept, an example that is qualitative, not quantitative, and “may” indicate support for a global MWP event. They allow the writers to write subsequent papers either way. They don’t stake a position. Nicely done.
There are geoscientists and there are “prospect makers” in the field of petroleum geology. One postulates, the other predicts. The climate scientists like these guys, Mann, Trenberth et al are the geo-scientist equivalents. Bastardi, Corbyn, Watts, are the prospect maker type, using their skills to advance the actuality of the human condition, not the imaginative fancy of the elite.
If scientists of all stripes were forced, by convention, to append all of their papers with definitive statements without the words “may”, “should” or “could”- with the principle that all such statements could be repudiated later, on the inclusion of additional information – we would be in a better position to use their work. Or falsify their positions.
Imagine if Mann had to say: my work says this happened, then. All we’d have to do is show that other work says it didn’t. And so his position would be falsified. Right now, how he/Gore present it, it cannot be falsified, as he never says A is. He says A might be, probably is. Never just “is”.
Arm-waving rhetoric. There should be a paper in that subject. Maybe, or it could be written. Possibly in Russian.

Bruce

The evidence for Global MWP is so strong, you could really make an article like this a weekly installment for WUWT along the lines of “MWP Update”. Surely drought in N Mex and SW US are tied to this Global trend too…ironic that the MWP phrase was first coined by HH Lamb who helped establish!

Billy Liar

Why has the δ18O panel A in the graph got its x-axis going the other way compared to the rest.
Am I missing something?

Bruce

To David (first post)-flat-lining is intrinsic to dendro-chronology, as detrending (accounting for differential biomass of trees, and thus relative width of rings, when deriving a width oscillation between trees of a given regional sequence), as a mathematical auto-function (see Jan Esper in Science 2002). Special requirements for long-term low-frequency pattern recognition are not understood it seems by Mann in this respect. I do not think he was a PhD in dendro-studies before his appointment, which makes one wonder about the motives of those appointing him in the first place! Many dendro-people will avoid employment of there data to make long-term reconstructions as a result, although high-frequency patterns, like there was a drought on a specific year, are less problematical.

Stephen Wilde

Quiet sun,vertically weak polar vortices become more extensive horizontally at the surface, climate zones and jetstreams move towards the equator from BOTH poles.
Active sun, polar vortices become more intense vertically but become smaller and more focused at the surface, climate zones and jetstreams move towards BOTH poles.

“They flatlined CO2 and temperatures for the one to two thousand year HS reconstructions. This allowed them to assign an artificially high weight to modern CO2 increases.”
wrong. Estimates of climate sensitivity of 3 happened well before the HS
Also, the estimates are constrained by MWP recons. LGM reconstructions
drive the central estimate for the ECR.
In short the HS is not that interesting or important.

Please note that modern warming does not happen in the SH,
as far as yet.
My overall average is 0.00 for the past 40 years in the SH
It seems the extra heat coming especially into the SH (as noted by increasing maxima) is moved by currents and weather systems to the NH where we find ca. 0,03 degrees C per annum warming for the past 40 years or so.
http://www.letterdash.com/HenryP/henrys-pool-table-on-global-warming
I am not saying it did not happen in the past, I am just saying it is not happening now.
I suspect a greater influence of the absence of ozone playing a role here, but there could also be other factors.

Steve C

Doubly interesting. It’s always nice to see a bit more support for the full-scale MWP, plus, ikaite (is that pronounced “eeka-ite”?) has to be the weirdest form of calcium carbonate ever. I’d say I want a bit, except it would melt!

Steven Mosher says: March 22, 2012 at 9:11 am
HS restrained by MWP, while LGM drives off the ECR (?!).

M Courtney

The MWP is embarrasing for alarmists for the other side of the CO2-causes-warming equation too.
Remember, the ice cores show temperature changes preceding changes in CO2 (not the other way round) by about 800 years. If the MWP was global then how do we distinguish between the output of CO2 from the oceans and the CO2 output of industrial civilisation?
Indeed, the ouput of the oceans may dwarf the industrial output. And that would be very embarrassing.

philjourdan

This is what a lawyer would call “circumstantial” evidence. WHile historical records are not perfect, there have been dozens of studies from human civilization that indicated the MWP was global in nature. These have been documented by anthropologists, and thus not part of the enforced dogma of the AGW cabal. Still, as scientists look for proof of the MWP, it appears they are finding it more and more.
I guess that was an unMANN made global climate change.

Steven Mosher said @ March 22, 2012 at 9:11 am

LGM reconstructions drive the central estimate for the ECR.

Little Green Men reconstructions drive the central estimate for the European Commission Representation. Sounds about right…

Niels A Nielsen

If the MWP is as warm as the modern warm period was, it was not caused by CO2. It was not caused by solar irradiance either. What was it then? Do the same factor(s) contribute to the modern warming?

sean2829

Calcium carbonate in its many forms coupled with its unusual solubility characteristics (it’s more soluble in cold water than warm due to bicarbonate forms) just keeps on amazing me. A very interesting study.

pat

““We showed that the Northern European climate events influenced climate conditions in Antarctica,” Lu says.”
LOL. I must have missed that section.

Pat says:
““We showed that the Northern European climate events influenced climate conditions in Antarctica,” Lu says.”
LOL. I must have missed that section.
Stephen Wilde says:
Quiet sun,vertically weak polar vortices become more extensive horizontally at the surface, climate zones and jetstreams move towards the equator from BOTH poles.
Active sun, polar vortices become more intense vertically but become smaller and more focused at the surface, climate zones and jetstreams move towards BOTH poles.
Henry says:
sorry guys.
In both cases you/they are wrong at least from the observed data from the past 40 years or so.
http://www.letterdash.com/HenryP/henrys-pool-table-on-global-warming
At the moment, (I mean the past 40 years or so) extra heat is going into the SH, presumably into the oceans, but it does not get any warmer there. It simply seems to travel to the NH where it does get warmer. Probably via currents and weather.
My data suggest that warming is due to, either
1) more intense heat from the sun
and/or
2) less clouds
and/or
3) less ozone
It seems to me the latter possibility is becoming the more critical option to look at.
Remember that that little layer of ozone upstairs cuts off almost 20% of all incoming (UV) sunlight. Water aborbs in the UV, and therefore a lot of it (the extra UV, or the more than normal UV) is converted to heat in the water.

Doug Proctor says:
March 22, 2012 at 8:19 am
There should be a paper in that subject. Maybe, or it could be written. Possibly in Russian.
Russians have done their best for the global warming.
http://www.vukcevic.talktalk.net/69-71.htm

Septic Matthew/Matthew R Marler

Steven Mosher: In short the HS is not that interesting or important.
To whom?
Mann has found it interesting enough and important enough to write a book accusing HS critics of misdeeds, and his book has earned high marks from climate scientists who agree with him about the importance of AGW. It was for a time so interesting and important as to be subjected to a review by the National Academy of Sciences, and it was defended by Schmidt et al in their critique of McShane and Wyner. It was for a time so interesting and important as to be on the home page of the IPCC.

mysteryseeker

I believe that most of the problem in trying to differentiate past climate in the far reaches of the Southern Hemisphere as to do with the very low resolution of Antarctic Ice cores. This is most defitely the case I beleive with the Younger Dryas. The one core near to the coast of the great ice continent (Taylor Dome) displays a climate lock step with the climate shifts in the Northern Hemisphere

Niels A Nielsen says:
“If the MWP is as warm as the modern warm period was, it was not caused by CO2. It was not caused by solar irradiance either. What was it then? Do the same factor(s) contribute to the modern warming?”
Dark energy flux 😉

Peter

Reading between the lines, it seems fairly certain that the authors of this paper all agree with the consensus on AGW. Just saying.

Niels A Nielsen says:
March 22, 2012 at 9:33 am
_________________________
The distribution of heat by ocean currents has been proposed as a principal factor in global temperature. The large and ongoing drop in temperature at about the time that Central America emerged to close the seaway between the tropical Pacific and Atlantic supports this hypothesis.

kadaka (KD Knoebel)

vukcevic said on March 22, 2012 at 9:22 am:

Steven Mosher says: March 22, 2012 at 9:11 am
HS restrained by MWP, while LGM drives off the ECR (?!).

Nah.

Estimates of climate sensitivity of 3 happened well before the (Hydrogen Sensor)
Also, the estimates are constrained by (Mid-Way Port) (re-conversions). (Low-emission Gas Monitor) reconstructions drive the central estimate for the (Exhaust Control Relay).
In short the HS is not that interesting or important.

He’s talking about problems with emission controls, obviously. Maybe he posted to the wrong blog.
😉

David A

Steven Mosher says:
March 22, 2012 at 9:11 am
“They flatlined CO2 and temperatures for the one to two thousand year HS reconstructions. This allowed them to assign an artificially high weight to modern CO2 increases.”
wrong. Estimates of climate sensitivity of 3 happened well before the HS
Also, the estimates are constrained by MWP recons. LGM reconstructions
drive the central estimate for the ECR.
In short the HS is not that interesting or important.
============================================
Intresting comment Mr Mosher. I hope you stick around to actually dialoge and not do your normal hit and run.
You may be right, however, If so, you are telling me that climate models, using the current IPCC CO2 weighting, applied to a “non” hockey stick reconstruction of past temperature, for instance Craig Lehole, or the 6000 borehole reconstruction, (both of which produce a MWP) and at the same time flatlining CO2 levels as the IPCC claims, will still produce a MWP given the same IPCC weightings to solar and other known factors. I challenge you to produce such a historic model using IPCC senstivity numbers and IPCC non peer reviewed models.
If you cannot, then perhaps once again you are not seeing the forrest, because of your propensity to over examine a few trees.

Ted G

Hi Anthony.
there is a mountain of peer reviewed evidence that the MWP was world wide. I have looked at and recorded most of them over the years. There are many great skeptical sites that report on this fact, your blog is one of the most important. Another great one is CO2 Headline’s it is all peer reviewed, a short essay and easy to digest with links to the authors papers.
Here is an Example and link:
Mann’s Discredited Hockey Stick Takes Another Huge Hit: South America’s Hot Medieval Temperatures
New research determines that South America did experience the Medieval Warming and temperatures were higher during MWP, contrary to Michael Mann’s hockey stick “science”
Read here. As hundreds of scientists have discovered and published, the Medieval Warming (MWP) climate was global in nature, with temperatures that in many areas of the world were higher than today’s temperatures.
http://www.c3headlines.com/2011/12/manns-discredited-hockey-stick-takes-another-huge-hit-south-americas-hot-medieval-temperatures.html

Nic Lewis

Steven Mosher says:
March 22, 2012 at 9:11 am
” LGM reconstructions drive the central estimate for the ECR.”
which I take it means Last Glacial Maximum reconstructions drive the central estimate (of 3 K) for the Equilibrium Climate Response, otherwise known as climate sensitivity.
That may be Hansen’s view, but I don’t think it’s the IPCC “consensus” view.
Apart from the supposed “evidence” as to climate sensitivity from GCM simulations, AR4 WG1 included ten studies that provided observational constraints on climate sensitivity in the key Table 9.3 and Figure 9.20 (also included in Box 10.2) in Chapter 9. Seven of those studies were based on instrumental data and provided PDFs (probability density graphs). Five of those PDFs peaked in the range 1.3 K to 3 K.
Only two of the ten studies featured in Figure 9.20 involved the LGM: Schneider von Deimling et al. (2006) and Annan et al. (2005). Per Table 9.3, the former gave an estimated climate sensitivity range of 1.2 K to 4.3 K, while the latter – which did not even consider sensitivities of <4 K – merely gave a <7% chance of sensitivity exceeding 6 K.
Moreover, AR4 WG1 concluded that LGM proxy data was so uncertain that the climate sensitivity estimates derived from it did not even provide primary evidence as to sensitivity:
"Therefore, LGM proxy data provide support for the range of climate sensitivity based on other lines of evidence." (Box 10.2, Ch.10)
"Overall, estimates of climate sensitivity from the LGM are broadly consistent with other estimates of climate sensitivity derived, for example, from the instrumental period." (Ch.9)

Gail Combs

Doug Proctor says:
March 22, 2012 at 8:19 am
….Arm-waving rhetoric. There should be a paper in that subject. Maybe, or it could be written. Possibly in Russian.
There already is a paper on it and it was written quite a WHILE AGO. (I hope my links are still good)
Plain Prose: It’s Seldom Seen in Journals. Written by Dick Pothier. If you want to publish an article in some scientific or medical journal, here is some unusual advice from Scott Armstrong
http://marketing.wharton.upenn.edu/ideas/pdf/Armstrong/Mass%20Media/Inquirer%201982b.pdf
J. Scott Armstrong (1980), Bafflegab Pays, Psychology Today, 12: http://marketing.wharton.upenn.edu/documents/research/Bafflegab%20Pays.pdf
The article would be very amusing if it did not have such serious ramifications in the field of science.
Scott Armstrong has done some other very good studies on research and how it is perceived.
(see: http://marketing.wharton.upenn.edu/people/publications.cfm?id=226&current_flag=0 )

Interstellar Bill

Hey, watch that! Only Warmistas get to use ‘global’ and ‘warming’ in the same sentence.
Perhaps we could assert that Viking fire-raids temporarily drove up medieval CO2, but for too short a time for the Greenland ice bubbles to register it..

Conradg

Stever Mosher: “wrong. Estimates of climate sensitivity of 3 happened well before the HS
Also, the estimates are constrained by MWP recons. LGM reconstructions
drive the central estimate for the ECR.
In short the HS is not that interesting or important.”
______________________________
Technically correct, in that high sensitivities were claimed by the IPCC before the HS come out, but also misleading The HS was important in trying to justify these claims of high sensitivity, which otherwise seem quite implausible. Also, the LGMs themselves rely on paleoclimate reconstructions to determine sensitivity, of which the HS is a crucial part.

Logan in AZ

Come on now — the Idso team at co2science has been running a special study on the global nature of the MWP for quite some time. From the first page of http://www.co2science.org
“Was there a Medieval Warm Period? YES, according to data published by 1060 individual scientists from 608 research institutions in 44 different countries.”
This site should invite an essay from the Idso group on this and other topics they have examined, such as the dimethylsulfide feedback.
When it comes to the MWP, the science is settled, and a consensus has obtained — outside of the AGW wonderland.

“We showed that the Northern European climate events influenced climate conditions in Antarctica,” Lu says…..!!! choke splutter…..
Did Lu actually say that? Talk about putting the cart in front of the horse!
Maybe Lu should take a few moments to glance at a map or even better look at the Antarctic satellite chart.
Loopy Lu!

Septic Matthew/Matthew R Marler says:
March 22, 2012 at 10:27 am
“Mann has found it interesting enough and important enough to write a book accusing HS critics of misdeeds, and his book has earned high marks from climate scientists who agree with him about the importance of AGW.”
If you think about it, this MWP paper makes the AGW conjecture even more questionable. The planet has been naturally warming within well defined parameters and along the same trend line since the LIA, with no evidence of temperatures accelerating above those parameters. Based on that fact alone, AGW appears to be not much more than hand-waving.

Stephen Wilde

“Henry says:
sorry guys.
In both cases you/they are wrong at least from the observed data from the past 40 years or so.”
Hi Henry. I don’t see that my proposal is inconsistent with your findings. It is the shifting of the climate zones that produces the energy distribution that you report.

David A

Smokey says:
March 22, 2012 at 1:24 pm
=============================
Smokey, please read my first comment, the first on this post, and read my reply to Mr Mosher here. David A says: March 22, 2012 at 11:19 am. I am very curious as to your thoughts on this??

Latitude

…so it skipped right over Africa and South America

Greg House

“The ~5‰ decrease in δ18Ohydra at the beginning of the MWP must indicate
very strong freshening at the bottom of fjord, likely due to meltwater
cascading to depth.”
============================================
Meltwater would experience some significant difficulties trying to “cascade” to the bottom of fjord, because it has lower density, than sea water (saltwater).
Since this “cascading” point is crucial, I would be a little bit sceptical about the conclusions.

Jim Clarke

The HS was bad science from the beginning, but great PR. Therefore, it was very important to the AGW community and was displayed prominently in the IPCC report that followed. Once it was discredited, IPCC supporters like Steve M. started saying that it was not important science. True enough! It would be nice if Steve M. would just admit that it was an emotionally provocative tool used to influence the ignorant masses to support the AGW agenda, since the REAL science was not (and is not) convincing enough to do it.
What is important is that the models cannot produce the natural climate variability of the past, because we do not know what drove it. Therefore, we can not determine what percentage of the recent warming is natural and what is man-made, and we can not predict future climate. Without a good understanding of natural climate variability, we can not determine the climates sensitivity to increasing CO2 with any accuracy, and the IPCC’s current estimate of that sensitivity is an agenda driven wild-a#% guess.

The scientists were particularly interested in crystals found in layers deposited during the “Little Ice Age,” approximately 300 to 500 years ago, and during the “Medieval Warm Period,” approximately 500 to 1,000 years ago.

Was there a global medieval warm period?
This question could be answered in the positive upon the evidence if it were re-phrased such:

Yes, in many regions around the globe there is evidence of a period of warming on a secular scale somewhere between the 9th and 15th centuries.

However, this is not the question.
Most people think of a global warm period, or climate optimum, as a general (average) increase in temperatures across the globe. Much of the evidence actually suggests that the warming occurred at different times in different areas. In many cases a warming of up to 2 centuries is preceeded and/or succeeded by cooling. Therefore, in a global account, these coolings might tend to cancel out warming elsewhere.
Therefore, I dont think it is very helpful for us to say: Look more evidence of a global MWP! whenever we see regional warming for a century or two somewere within a 5 century timeframe.

David A. Evans

Why are we still discussing Global temperatures? We already know this is a meaningless metric!
Because we had a birdstrike and my warm clothes were still on the plane, I was wandering around Gander, Newfoundland in February in shirtsleeves. Yes it was damned cold but not intolerable! The energy content, and also its capacity to extract energy is entirely related to humidity.
So, Without information on humidity, temperature is useless! A corollary to this is that yes, Global warming will be seen in the Arctic, amplified! Work it out Mosh!
DaveE.

Allan MacRae

This paper provides further vindication for Soon and Baliunas (2003) – see Excerpt below.
What hurts is not just the vicious lies, fraud and the intimidation of the warmist camp.
It is the criminal waste of a trillion dollars of scarce global resources that could have been used to ease the plight of the world’s poorest people, instead of being squandered on the global warming scam. A trillion dollars would go a long way to providing clean drinking water and sanitary systems for every person on Earth.
A few million kids die from drinking contaminated every year. In the years since the 1972 Rio summit, the number of kids who have died from bad water probably exceeds all those people of all ages killed in WW2… … and so it continues to this day.
What also hurts is the damaged and destroyed careers of some honorable, talented people, who have been driven out of their positions by the dirty political game that global warming mania has engendered.
I believe the time will soon come when natural global cooling will finally and utterly falsify the CAGW Hypothesis, and consign it to the dustbin of history.
But huge damage will have been done, and the perpetrators of this horribly expensive, wasteful CAGW fraud will sail on.
______________
Excerpt
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.
Source: Energy and Environment (2005)
Full article: http://wattsupwiththat.com/2011/11/28/the-team-trying-to-get-direct-action-on-soon-and-baliunas-at-harvard/

Greg House

Allan MacRae says:
March 22, 2012 at 10:14 pm
I believe the time will soon come when natural global cooling will finally and utterly falsify the CAGW Hypothesis, and consign it to the dustbin of history.
=================================
Yeah, very optimistic. Global cooling can also be attributed to the human activities and we will have the same game again.

zefal

“We showed that the Northern European climate events influenced climate conditions in Antarctica,” Lu says
European’s climate RULED the Antarctic! It was what would be Europe’s first insatiable taste of colonialism.

HenryP says:
March 22, 2012 at 10:17 am
In both cases you/they are wrong at least from the observed data from the past 40 years or so.
http://www.letterdash.com/HenryP/henrys-pool-table-on-global-warming
At the moment, (I mean the past 40 years or so) extra heat is going into the SH, presumably into the oceans, but it does not get any warmer there. It simply seems to travel to the NH where it does get warmer. Probably via currents and weather.
My data suggest that warming is due to, either
1) more intense heat from the sun
and/or
2) less clouds
and/or
3) less ozone
It seems to me the latter possibility is becoming the more critical option to look at.
Remember that that little layer of ozone upstairs cuts off almost 20% of all incoming (UV) sunlight. Water aborbs in the UV, and therefore a lot of it (the extra UV, or the more than normal UV) is converted to heat in the water.

Even with the reduction in Ozone, the amount of UV (which is vary small percentage of TSI anyway) reaching the surface is still very small. I suggest less clouds from ~1980-1998 as empirically measured by ISCCP and Palle et al’s Earthshine project are the more likely cause of the modern warming period, (and quite possibly the medieval warm period too).