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Medieval Matt

Matt Ridley's latest Wall Street Journal column is on the medieval warm period.

I consulted a database of papers collated by the climate-skeptic website, run by the Center for the Study of Carbon Dioxide and Global Change, a nonprofit research center in Tempe, Ariz. The database contains numerous published studies of isotopes and other indicators in caves, lake sediments and other samples from Chile, New Zealand, South Africa and Antarctica that find the MWP warmer than today. Two Antarctic studies, for instance, concluded that current warming "is not yet as extreme in nature as the MWP" and that "the present state of reduced ice on the western Antarctic Peninsula is not unprecedented." A far smaller number of studies, such as one from Lake Tanganyika, found the MWP cooler than today.

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Reader Comments (24)

The problem with real science is that like Matt it is really difficult to make a case from the evidence whereas warmist can get away with anything by just pontificating about their (phonebox) consensus.

Personally, I 've looked at climate records and what is recorded in proxies seem to bare no resemblance to known historical events. E.g. it is well known that the bronze age was a lot warmer/drier (mainly because bronze age huts are found in the higher areas where no one could farm today). The only way to explain that is climate change, but when you look at the climate proxies such change is almost indiscernible.

That either suggests that we have misunderstood the role of these huts (perhaps they were for bronze age new-age pagans to star gaze?) ... or the climate proxies are carp.

My view is that the climate proxies appear to be next to useless for long-term change (they might highlight the effect of a volcano but not changes over centuries). And if you want to know what the climate was like, there is no alternative than plain and simple archaeology to find out what was growing where and when. You can't fudge people living on the high areas of Britain, likewise greenland, likewise grapes in the N.of England and until I see a proxy that fits with what we know from good solid archaeology ... they can all go jump in a bog.

Nov 11, 2012 at 8:13 AM | Registered CommenterMikeHaseler

Mike, archaeology has been greatly downplayed, I'm sure you're right about that. But that means facing up to colossal gaps in our knowledge of the past. We're not good at saying we don't know, especially when large grants are at stake. How this habit of inferring false signal from misunderstood data auto-corrects I don't know. But it must.

Nov 11, 2012 at 8:38 AM | Unregistered CommenterRichard Drake


The recent Christiansen and Ljungqvist multi-proxy suggests almost 2 C NH variability over the last 2000 years. I'd have imagined this level of variability would be consistent with the archaeological record. Do you think the actual variability is greater still?

Nov 11, 2012 at 8:43 AM | Registered CommenterPhilip Richens

I've seen the Idso's in action for three decades.

The Four Corners country is dominated by a gaugantuan coal fired power station, and the Center for the Study Of CO2 is an almost comically devoted creature of the mines that supply it.

Nov 11, 2012 at 8:43 AM | Unregistered CommenterRussell

Any actual evidence for that claim Russell?
Climate Science at its finest.

Nov 11, 2012 at 8:56 AM | Unregistered CommenterEddy

Some proxies are better than others. Some can be verified in controlled conditions and their accuracty validated in double blind experiments

Nov 11, 2012 at 10:01 AM | Unregistered Commenterconfused

"...or the climate proxies are carp"

Very fishy

Nov 11, 2012 at 10:04 AM | Unregistered CommenterDavid Chappell

The MWP was of course the last maximum in a natural cycle of about 1,000 years which was evident for several thousands years before that.

The evidence of planetary effects on climate has been around for years. We can see a ~1,000 year cycle (previously mentioned in WUWT posts) and a 60 year cycle which was rising for 30 years prior to 1998, but is now declining, offset in part by slight rising in the 1,000 year cycle as it approaches a maximum. .

Hence the last 14 years of world climate records clearly indicate that there has been no net warming since this time in 1998. That is, there has been no net accumulation of energy in the Earth system - probably a slight loss in fact. So net radiative imbalance at TOA must also have been in accord with a cooling climate, not a warming one.

But all those energy diagrams and models "predicted" carbon dioxide would cause extra warming. If this fails to happen in 14 years, it can also fail to happen in the next 600 years, by which time I predict the world will be back at a minimum similar to the Little Ice Age.

The reason the energy diagrams are wrong is because they assume (and clearly indicate) dual heat flows between the surface and the atmosphere. They imply that radiation always transfers heat in the same direction. They assume that, if the net heat transfer is from hot to cold, then all is OK. But the two processes they assume happen are independent. A heat flow by radiation from the cooler atmosphere to the warmer surface does not force a greater flow of radiation out of the surface which is due to the surface being warmed more. Any such preliminary warming, no matter how infinitesimal, would be a violation of the Second Law of Thermodynamics.

The only possible correct physical explanation is that which I have summarised starting on p.47 of Joseph Postma's October 2012 paper. My reasons for such are also therein.

Unless and until scientists understand when and by how much radiation transfers heat, they will continue to fumble with hypothetical, invalid concepts which mislead the world with their carbon dioxide hoax.

Nov 11, 2012 at 10:26 AM | Unregistered CommenterNaturalCyclist

Here's me planning a post for later in the morning (other commitments prevented me from sitting down to post when I first read this thread) suggesting that going overboard for the CO2Science findings is not the best of ideas because a) it is a sceptical site and b) it was - as far as I know - set up with the express intention of providing a counter-balance to some of the wilder claims for CO2.
So the warmists hate it.
Then up pops Russell to prove my point for me. So predictable, these warmists, aren't they?
Russell, let me try to put this in simple English. It doesn't matter who produces the data. What matters is that they are accurate. Precisely which bit of

Was there a Medieval Warm Period? YES, according to data published by 1113 individual scientists from 637 research institutions in 46 different countries ... and counting!
are you disputing? Do tell.

Nov 11, 2012 at 11:33 AM | Registered CommenterMike Jackson

Some proxies are good but some very questionable. Tree ring data is not only a measure of temperature but rainfall, sun/cloud, wind, soil type, soil minerals, the list is extensive and mine not the total by any means. Temperature proxy by tree ring is therefore very poor. (Dr. Mann please note)

Nov 11, 2012 at 11:48 AM | Unregistered CommenterJohn Marshall

Climate temperatures of ages past will always be subject to a degree of murkiness. Science will always have folks that challenge any single point. Without the temperature records T-Rex made with his 1/20th degree accurate thermometers, one is left with only approximate measures. The paleo records seem to contribute by establishing boundaries but not accuracy. For example, finding fossile tomatoes in Greenland under a few km of ice might mean (1) they grew before the ice or (2) some paleo oil driller dropped his lunch down a bore hole.

Which allows those with political agendas to defend just about any scheme they devise if they use pre-satellite records for global temperature. One such blogger/journalist said it best when he complained about the "other side" just outright lying whereas "his side" always had at least one fact. Of course, it didn't matter what the fact was - just that "his side" could use it to hang their claims. Fittingly, the writer was a warmist.

Nov 11, 2012 at 11:57 AM | Unregistered Commentercedarhill

There is of course lots of evidence that the MWP period was warmer.

If you go to Iceland for example, you find that its current ice cap which extends over more than 1300 square miles was only about one third this size and actually split in two during the MWP.

Warmists won't argue that this kind of evidence is untrue. They will simply downplay or preferably just ignore it.

Nov 11, 2012 at 12:19 PM | Unregistered Commenterdave

After 40 years research, I have discovered that camel toe clippings are a reliable proxy for indicating temperature.

Nov 11, 2012 at 12:50 PM | Unregistered CommenterAnoneumouse

OT BBC director Entwistle resigned.

"Mr. Entwistle’s sudden departure as the BBC’s chief executive was prompted by outrage over a report last week on “Newsnight,” one of the network’s flagship current affairs programs, that wrongly implicated a former Conservative Party politician in a pedophile scandal involving a children’s home in Wales.

Mr. Entwistle said the report, broadcast on Nov. 2, reflected “unacceptable journalistic standards” and never should have been broadcast. "

The BBC, unacceptable journalistic standards? Who knew? :)

Nov 11, 2012 at 1:21 PM | Unregistered CommenterDon B

John Marshall

Tree ring data is not only a measure of temperature but rainfall, sun/cloud, wind, soil type, soil minerals, the list is extensive and mine not the total by any means.

You could add the size of the salmon run. Bears eat salmon, then they do what bears do in the woods. Result better tree growth.

Nov 11, 2012 at 3:51 PM | Registered CommenterDreadnought

A far smaller number of studies, such as one from Lake Tanganyika, found the MWP cooler than today

Tha warming of Lake T is extremely fast, so fast that it provides a nice poster child for the 'look, it's worse than we thought' alarmists. However, far from presenting them with evidence for the greenhouse effect, the record warming presents a problem, Why should this small area be uniquely affected by CO2?

Let me help.

The effluent from approximately 2.5 million people flows into the lake. This will include about 1/3l of spilled/discarded/flushed away light oil per person and an unknown amount of surfactant. The surface of the lake will be covered with a smoothing film at least twenty times in a year, so much that, whenever the windspeed drops below about 7 m/s, surface effects will be dominated by the film. Lower albedo, lower emissivity and reduced evaporation will all warm the lake.

I'm not surprised that the lake is warmer today than it was during the MWP. I _am_ surprised that no-one wonders why. Prof. Tom Wigley noticed the warming of the Atlantic during WWII -- 'why the blip?' he asked. OK, Professor, why is the lake warming at a rate not predicted by theory? You were once a scientist -- try to recapture that sense of curiosity. Why is this lake warmer today than during the MWP?

Who seems to be turning into mdggn....

Nov 11, 2012 at 5:01 PM | Unregistered CommenterJulian Flood

Mike Haseler

That either suggests that we have misunderstood the role of these huts...
Mike, I don't know from nothing, but is it conceivable that these huts were for summer living only while the flocks and herds were on high ground? When the colder weather returned in the autumn they would go back to lower levels. The practice continues in the alps today, to an extent.
I'm only surmising, you understand.

Nov 11, 2012 at 5:36 PM | Registered CommenterMike Jackson

Let us not forget the sacred memory of Baliunas and Soon (2003). Their extensive review of the literature is worth reading, if only to try to find out why Greenpeace would describe it as "a now thoroughly debunked study."

Amazing that a review of the literature should deserve such comment.

Nov 11, 2012 at 6:08 PM | Unregistered CommenterThe Iceman Cometh

Mike Jackson. Good point. According to Francis Pryor in one of his books, Bronze Age farming was intensive livestock farming mainly, and upland areas were used as pasture for cattle and sheep. However, the Bronze Age in Britain lasted a long time. The Late Bronze was very much akin to the Iron Age and the Early Bronze, from about 2300BC, possibly even a little earlier, was an extension of the Neolithic. It is in the Middle Bronze age that most of our field and farm boundaries were established. It must depend where in that 1500 year period the huts are dated in order to reach a conclusion about what the climate may have been like. This is in fact what is known as the Minoan Warm Period by some commenters on the web. I've not read of this in the literature but you never know.

Nov 11, 2012 at 8:09 PM | Unregistered Commentercarol smith

Notice the date on this report anyone know if these islands are still there .

Nov 11, 2012 at 9:00 PM | Unregistered Commenterjamspid

Small question the Romans built the fish tanks into the cliffs at the same level as the high tide line to stop the fish escaping.
This place in Italy is it in an Earth Quake zone?
Explain why the gate level has dropped.

Nov 11, 2012 at 9:26 PM | Unregistered Commenterjamspid

RichardSCourtney gives a detailed explanation in this post explaining how there may be slight net warming of oxygen and nitrogen molecules resulting from prior absorption of IR by carbon dioxide molecules. Clearly he agrees that the effect is only slight.

But what then happens to the additional kinetic energy in the oxygen and nitrogen molecules? Well, firstly, assuming they are cooler than the surface below, the thermal energy cannot be transferred back to the surface by non-radiative processes. One way or another it must eventually escape to space.

But why to space? Don't the energy diagrams show (more than) half being returned to the warmer surface by radiation? This is where the biggest misunderstanding occurs. Radiation from a cooler source can do one and only one thing when it strikes a warmer surface. It slows the rate of that portion of surface cooling which is due to radiation. It does not do this by transferring heat to the surface. Because there is no heat transfer, there can be no slowing of non-radiative cooling processes. In fact, these processes can and do accelerate to compensate for the slower radiative cooling. What happens is that the energy in the radiation from the cooler atmosphere can only be used to supply equivalent energy to the surface which can only be used for the purpose of creating equivalent upwelling radiation with the same frequencies and intensities. This energy is thus used by the surface (instead of some of its own thermal energy) to meet some of its Planck "quota" of radiation. Its own Planck curve always fully contains the Planck curve of the radiation from the cooler atmosphere. But the radiation corresponding to the area above the cooler Planck curve, but under the warmer one will transfer heat. This is an empirically confirmed result, demonstrated over and over again. The area between the Planck curves represents the one-way heat transfer from the warmer body to the cooler one. There is no physical heat transfer the other way. The radiation from the cooler body is immediately re-radiated without any of its electro-magnetic energy ever being converted to thermal energy in the target.

Hence most of the observed (or calculated) upwelling radiation from the surface is not actually transferring heat from the surface. Rather it is merely sending back the energy that was in the backradiation. The whole process is very-similar energy-wise to diffuse reflection.

What then are the consequences of this discussion? Well, firstly the heat that is transferred from the surface to the atmosphere is mostly transferred by non-radiative physical processes such as molecular collisions which may be called conduction or diffusion. Using K-T energy diagrams, and remembering that that the amount of backradiation should be deducted from the upwelling radiation from the surface (because this amount is not transferring energy from the surface) then we can calculate that less than 15% of all energy transferring from the surface to the atmosphere does so by radiation.

Now we start to see the role of carbon dioxide in perspective. For a start it probably has less than 1% the effect of all the water vapor which radiates with far more spectral lines and thus slows radiative cooling much more effectively. (Yes, low clouds do slow radiative cooling noticeably, but that doesn't mean carbon dioxide's effect will be noticeable.)

But, more importantly, the non-radiative cooling processes significantly dominate the actual transfer of energy from the surface to the atmosphere. Any slowing of radiative cooling will leave a bigger temperature "step down" between the surface and the adjoining air. So non-radiative cooling processes will simply accelerate (as physics tells us) and have a compensating effect. So there will be absolutely no net overall effect on surface cooling. That is reality.

The 33 degree of warming claim has been absolutely rubbished in various PSI papers. Just browse the publications menu on our Home page.

There is no such thing as a greenhouse gas, because there is absolutely no atmospheric greenhouse effect caused by any gas or water vapour. The temperature of the surface is determined by incident solar radiation levels and the adiabatic lapse rate, the latter being a function of gravity.

Nov 11, 2012 at 11:03 PM | Unregistered CommenterNatural_Cyclist

" A far smaller number of studies, such as one from Lake Tanganyika, found the MWP cooler than today."

With the political established UNFCCC from Rio 1992. What matters is less what is right or correct scientific, but more what is conform towards this political established UN convention?

Nov 12, 2012 at 6:53 AM | Unregistered CommenterJon

Consider two parallel metal plates, one of them at 299K and one at 300K. The plate at 299K will send some radiation towards the 300K plate, and this will cause the 300K plate to cool more slowly. But the 300K plate would cool a lot faster if it were out in space in the shade of the Moon, say. Yet the radiation from it would be the same in each case, filling out the same Planck curve.

Think about what is happening. When the 299K plate (still at about that kind of temperature) is radiating towards the 300K one, the energy in the radiation is used to supply a lot of the energy required by the 300K plate to allow it to radiate its full Planck "quota" of frequencies and intensities. It cools much more slowly than in space because a far smaller proportion of the radiation from it is actually using up its own thermal energy. But whilst in a nice shady spot in space, nearly all its radiation is in fact using up its own thermal energy, so that radiation is nearly all transporting the plate's own energy into space.

So it is with the Earth's surface. Because of the presence of low level air at nearly the same temperature, the majority of the radiation coming up from the surface is not actually transferring thermal energy from the surface to the atmosphere. The energy for most of the upwelling radiation comes from the energy in the backradiation. This leaves other non-radiative processes to dominate with the surface cooling process.

Nov 12, 2012 at 8:55 AM | Unregistered CommenterDoug Cotton (Natural_Cyclist)

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