Steve McIntyre points out some inconvenient data from Law Dome.
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Re-reading Climategate and AR4 Review Comments, I noticed an interesting discussion about handling the Law Dome O18 record – a series used in Mann and Jones (2003) and Jones and Mann (2004) with a very elevated MWP.
The Law Dome O18 series was illustrated in Jones and Mann 2004 as follows (although the digital data for most series in this article was commendably archived, the digital version of the Law Dome O18 series wasn’t. After a couple of years of effort, I obtained it from Tas van Ommen.
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AR4 Second Draft Figure 6.11 purported to show the “locations of temperature-sensitive proxy records with data back to 1000, 1500 and 1750″, but, for some reason, didn’t include Law Dome, Quelccaya and other sites. The caption was as follows;
Figure 6.11. Locations of temperature-sensitive proxy records with data back to 1000, 1500 and 1750 (instrumental records: red thermometers; tree-ring: brown triangles; boreholes: black circles; ice-core/ice-boreholes: blue stars; other records including low-resolution records: purple squares). All proxies used in reconstructions [R1] to [R11] of Northern Hemisphere temperatures (see Table 6.1 and Figure 6.10) or used to indicate Southern Hemisphere regional temperatures (Figure 6.12) are included.
Neither was the Law Dome O18 data shown in Figure 6.12, illustrating SH proxy histories.
IPCC AR4 Second Draft Figure 6.12
The IPCC stated of this data:
Taken together, the very sparse evidence for Southern Hemisphere temperatures prior to the period of instrumental records indicates that warming is occurring in some regions. However, more proxy data are required to verify the apparent warm trend.
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But of course, that’s not all there is to see.
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Steve writes:
Just in case you wondered what Osborn and Overpeck didn’t want you to see, here it is:
Note that the inversion of borehole temperatures raises interesting questions equivalent to principal component retention – see prior posts on this. I’ve asked the Danish institution for the pre-inversion borehole measurements.
Read the complete story here at Climate Audit
“Chris G (12:34:58) :
[…]
That CO2 is not a GHG? If so, please go open a physics textbook, and try to read it.
That more GHGs do not lead to more warming? Please see the definition of a GHG, and again, open a physics textbook.”
Do CO2 and H2O not compete for the same frequencies? Is the CO2 GH effect not nearly saturated even without taking this competition into consideration? Your strategy of showing it as simple and proven don’t work here.
Chris G (12:34:58) :
You have no physical basis for your non sequitur:
“… the fact that there have been climate changes in the past in no way refutes that CO2 is the dominate driver the changes we are seeing in the past century.”
There is zero empirical [real world], testable evidence that CO2 is a significant forcing of temperature. None. There is radiative physics, which is fine as far as it goes. But we really know too little about the climate to state that “CO2 is the dominate [sic] driver [of] the changes we are seeing in the past century.” That is an evidence-free claim.
Any effect from CO2 depends on how sensitive the climate is to additional CO2 – the climate sensitivity number – and also on CO2’s persistence in the atmosphere. Keep in mind too that human additions to natural CO2 emissions are only about one molecule in 34. Almost all CO2 emitted from all sources is due to natural emissions.
The planet has warmed around 0.7° C in more than a century, while CO2 has risen by about one-third. But did the rise in CO2 cause that rise in temperature? Or are there other factors at work, such as natural warming from the Little Ice Age? Or was the CO2/temperature correlation completely specious? In other words, did the planet happen to warm naturally at the same time, coincidentally and independent of CO2? There is evidence for that.
The fact that on all time scales, changes in CO2 follow changes in temperature is a mighty big clue. People who say “This time it’s different” are invariably proven wrong, whether they’re predicting it will never rain again because they’re in a long drought, or predicting a permanent new plateau in the stock market.
CO2 has the same effect on the climate whether it’s now, or a thousand years ago, or ten million years ago. The laws of physics don’t change.
The climate has gone into major Ice Ages when CO2 has been many times higher than it is today. In fact, the only correlation between CO2 and temperature is that CO2 follows temperature. It has never been proven to be the cause of temperature changes. Since cause cannot follow effect, why – exactly – would radiative physics act differently now? Why would CO2 suddenly become the cause? Please answer using verifiable evidence.
You ask: “how much warming do you predict from a doubling of CO2? And how do you arrive at that figure?”
A generous answer is: a little over 1.6° per doubling from pre-industrial levels; about 280 ppmv. So we’re looking at a maximum of about 0.8° to go: click
But based on the ever declining estimates of climate sensitivity, that number is probably too high. And even if it’s correct, there is no problem with an additional 0.8° temperature rise; the beneficial effects far outweigh any negatives.
Finally, you say that “the agenda of this site is to refute AGW theory [sic].” That is wrong.
The purpose of this site is to find correct answers. Since all honest scientists are skeptics first and foremost, we do not accept scary proclamations based on always-inaccurate GCMs, none of which can make accurate predictions. Nor do we accept peer reviewed opinions that fail to provide the raw data and methods they are purportedly based on.
The climate peer review system has lost its credibility. It has been corrupted by money, by status, by constant expense paid trips around the world, and by its allegiance to the political appointees in the IPCC, rather than to the taxpaying public that pays their basic salaries. Skeptical scientists soon find that if they want to be invited to holiday conferences, or have their papers published, they had better keep their skepticism to themselves.
The author of this article, Steve McIntyre, was never the beneficiary of the loot flowing to the climate alarmist contingent, so he has no reason to invent alarming hypotheses. He is the primary reason that the Mann hockey stick chart was debunked. You can learn more honest science here than from all the IPCC political appointees put together. And it’s all free.
D. Patterson
“…they only used 3 ice cores”
How devious! Do you realize that each few mm core is a sample? If you have several 100s of samples in a sequence that gives a MWP pattern that is repeated in other holes is good sampling. Choosing 3 trees and rejecting a hundred others that were available is malpractice. Gee they only use one thermometer at a town -is this enough to show global warming for a hundred years? Worse, if you are happy with carefully choosing 3 trees to create the hockey stick, which even the creators have now rejected, why would your masters hide the three cores evidence if they were seeking truth? With what has transpired since NOv 09, I have to wonder how hard it was to convince you of agw in the first place – clearly its a political thing with you.
Steve,
I went to the entire thread on your website that was linked here, and want to express my appreciation for what you are doing. So many of the ‘CRUtape letters’ are meaningless without the back story, and here you are, providing the context that is missing in a series of e-mails that reveals yet another series of scandalous treatments of science by Jones et al in their quest to get only the desired answer. Keep up the great work! There will have to be a Vol. 2 of The CRUtape Letters!
“If there was a MWP, and it was not confined to the North Atlantic where we have written evidence of its reality, then the present warming is not unprecedented and CO2 is not implicated one way or another. Simple enough to bury AGW forever, is it not?”
You’re not even wrong, because you make an elementary logical fallacy.
Here’s an analogy:
We have an arson suspect for whom we have some material evidence that he started a bushfire. We also know that lightning has started bushfires since long before humans existed.
Does the latter fact disprove the charge that the suspect commited arson? If you believe so, then you’re making exactly the same logical fallacy.
This is the problem with the climate change “debate”, that it is so riddled with logical fallacies and other elements of pseudoscience.
Ed (09:04:37),
Just put a period after “unprecedented” in the first sentence, and we’re good to go.
I don’t understand your point Smokey. If you split that sentence up then it changes the meaning completely and no longer says that the a worldwide MWP disproves AGW in my opinion. The existance of a worldwide MWP is logically decoupled from the existance of AGW and it just becomes a collection of unlinked assertions.
Ed (11:30:50),
I was being facetious. Sorry, I should have put “/sarc” under my response. If I had been arguing seriously, my explanation would have been more than a sentence.
When I went to school there was never any question about the MWP. The physical evidence showing that it occurred and was warmer than now is found throughout the world, in both hemispheres.
Because a warmer MWP debunks the idea that human emitted carbon dioxide has anything but an insignificant effect on the temperature [if that], those who stood to gain from the CO2 scare needed to show that we are currently undergoing unprecedented warming. Since we’re not, they had to do something about the MWP problem.
Dr. David Deming of the University of Oklahoma testified to a Senate subcommittee in 2006 that he received an email from a colleague [who thought Deming was with the alarmist crowd], stating, “We have to get rid of the Medieval Warm Period.” [source]
And of course Michael Mann was debunked by Steve McIntyre after Mann attempted to show that the MWP was cooler than now: click
The fabrication that the MWP was only regional is a desperate attempt to prop up the increasingly ridiculous catastrophic AGW hypothesis. The MWP lasted for 400 years. There were short-lived cooler periods during those four centuries, but overall the MWP was significantly warmer than today: click
There is no credible evidence that the MWP was confined to one location on the globe, at one general latitude. That would pretty much violate the 2nd Law of Thermodynamics, since winds and ocean currents would tend to even out global temperatures over four hundred years.
I was being sarcastic because only the most credulous true believers in the evil of “carbon” [by which the ignorant mean CO2] still argue that the MWP was a local “anomaly.” With a warmer MWP, the whole CAGW hypothesis is unsupportable.
The existence of a long-term, global, significantly warmer MWP implies that “We’ve been here before” in terms of temperature and that:
1. No runaway warming effects occurred. E.g., from decreased albedo and methane-released-from-permafrost. (Apparently shrubs start growing in the tundra to shade the permafrost — a negative feedback that was recently discovered.) The sea level didn’t rise alarmingly.
2. The Present Warm Period (PWP) is well within the range of recent-historic natural variation, making it less likely that CO2 is the major cause of it, and reducing the credibility and/or strength of the greenhouse gas argument.
3. The warmist establishment, including the IPCC, that tried to erase the MWP and created the hockey stick, has been “crying wolf.” I.e., the alarmists are “globally” untrustworthy. This is the most important implication of this controversy.
Sure, but how much will it rise? If there are no large positive feedback effects, it’s not worth worrying about.
Are there any realistic alternatives to coal and oil (aside from new-tech nuclear)? Surely there are some “no regrets” policies we could all agree on, like encouragement for better insulation and for the use of natural gas for heating. But major penalization of carbon would be economically devastating.
If “we” (the developed world) do reduce our emissions, will developing countries like China curtail theirs significantly? (Very unlikely IMO.) If not, why bother?
If “we” (the entire world) do reduce our emissions, will that have a noticeable effect on atmospheric CO2? (Very unlikely according to Monckton.) If not, why bother?
Has the effort by the EU to penalize emissions and encourage the development of renewable energy sources lived up to the hype of its promoters, or has it mostly fallen flat? If the latter, why follow in its footsteps?
Have the alarmists established their credibility as trustworthy guides — or mostly as faddish, sophistical, and partisan alarmists? If the latter, their credibility is that of other advocacy groups and causes — low.
I don’t want to go into all the details of these points. There’s an immense amount of justification for a “keep cool” position on this site in the archived threads. (I only wish that the 10% best articles and comments were flagged or highlighted to make skimming by new visitors easier.)
You still don’t present any logical case for a worldwide MWP disproving AGW. These past temperature reconstructions have fervently gripped the popular imagination, but they do not in themselves prove much in regards to AGW. Instead, it is detailed analysis of 20th Century data, not pre-instrumental data, that provides evidence for AGW. Simply put there is evidence for warming that cannot be explained through natural phenomena in the 20th Century-present, eg historically warm temperatures at a time when natural variables such as the output of the sun are historically “cool”.
Let us imagine that all these studies were wrong and that the MWP was worldwide and significantly warmer than today. That would simply prove that natural causes can cause warming greater than we have seen in recent decades. Yet this is already known, and not controversial; we have evidence that the last interglacial was significantly warmer than today and that sea-levels were 6-8m higher than now. We know the Paleocene-Eocene Thermal Maximum of 55 million years ago was dramatically warmer than today, with sub-tropical forests growing well within the Arctic Circle.
I am intrigued by your assertion that regional climate change violates the Second Law of Thermodynamics. Have you got any reliable sources for that? Even as a non-physicist it strikes me as unlikely. Here’s why. Climates are not distributed in neat latitude bands around the world, but are strongly influenced by ocean circulation etc. North West Europe is much warmer than other locations at a similar latitude because of the North Atlantic Drift. Drift Ice in the Sea of Okhotsk reachest the same latitude as the mild Adriatic Sea. Would it violate the 2nd Law of Thermodynamics for a weakening and strengthening North Atlantic Drift to cause a cooling and warming of Europe, for example? I think not.
Steve McIntyre is the only significant paper from a reliable source to make these findings, as far as I am aware, and what is more was published in a journal of social science, which surely makes it far less compelling than those that came to a different conclusion published in respected natural science journals. Further, his paper was rejected by Nature (probably the most prestigious scientific publication in the world) as faulty and has been criticised as having a faulty method by Rutherford et al in Journal of Climate. Since then his findings have not been published in scientific publications, only in opinion pieces and other non-peer-reviewed publications.
Thus to rely on this particular source is troublesome; one of the distinguishing characteristics of pseudoscience is to rely heavily or almost exclusively on one study’s findings while ignoring a much larger number of studies that are contradictory. Mann’s findings, which McIntyre attacked, were not unique, but similar to findings by multiple independent teams.
Speaking of reliable sources, what reliable sources (ie peer reviewed scientific journal sources) do you have for the sweeping statement “with a warmer MWP, the whole CAGW hypothesis is unsupportable”? It seems as though you dismiss Nature and other highly regarded scientific publications as “credulous true believers in the evil of ‘carbon'”, in favour of, it would seem, non-scientific internet opinion pieces. This leaves your argument with little weight.