In response to criticisms from Gavin Schmidt, Craig Loehle and J Huston McCulloch have published a correction to Loehle’s temperature reconstruction that uses 18 non-tree ring proxies. The pdf of original paper and the correction can be found here.
The corrected Figure 2 can be seen below:
The MWP and LIA remain prominent, in contrast to ‘Hockey Stick’ style reconstructions. However, in terms of reconstructions involving tree rings, as Steve McIntyre points out, if Yamal instead of Polar Urals update are used, you can get Modern Warm Period higher than MWP and vice versa; similarly with Indigirka versus bristlecones; or depending on Mann PC1 bristlecones versus Ababneh bristlecones.
In short, the jury is still out on whether the MWP had a global influence or if it was warmer than the Modern Warm Period. Nevertheless, the Loehle reconstruction makes a valuable contribution to the debate and should be included in the IPCC spaghetti graph that replaced the Mann et al Hockey Stick in AR4.
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
This is to remind readers of the Mann Hockey Stick in AR4 for comparison:
http://whyfiles.org/218glo_warm/images/hockey_stick.jpg
That is AR3 (2001).
This is the most convincing evidence that I have across on the internet of AGW:
http://www.cse.unsw.edu.au/~lambert/parody/tcs/soonlegatesfig1.gif
Some very dodgy wood in that hockey stick!
And if you include the current temperature record, you get a hockey stick. If you include the projected temperature rise, you get an even bigger hockey stick.
So what was the point?
Anyone interested should be discussing the sudden rate of change round the time we got thermometers.
SJT – add the current temp record and you get a boomerang – not a hockey stick!
Ender – in the UK we got themometers in the LIA, 1659.
Here are links to papers that find evidence of the MWP and LIA in South Africa, New Zealand, and Antarctica.
SOUTH AFRICA
http://www-user.unibremen.de/~gheiss/Personal/Abstracts/SAJS2000_Abstr.html
From the abstract of, “The Little Ice Age and Medieval Warming in South Africa”
“The Little Ice Age, from around 1300 to 1800, and medieval warming, from before 1000 to around 1300 in South Africa, are shown to be distinctive features of the regional climate of the last millennium.”
“The climate of the interior of South Africa was around 1oC cooler in the Little Ice Age and may have been over 3°C higher than at present during the extremes of the medieval warm period.”
NEW ZEALAND
http://hol.sagepub.com/cgi/content/abstract/14/2/194
From the abstract of “Speleothem master chronologies: combined Holocene 18O and 13C records from the North Island of New Zealand and their palaeoenvironmental interpretation”
“Increasingly negative 18O values after 7.5 ka BP indicate that temperatures declined to a late mid-Holocene minimum centred around 3 ka BP, but more positive values followed to mark a warm peak about 750 years ago which coincided with the ‘Mediaeval Warm Period’ of Europe. Low 18O values at 325 years BP suggest cooling coincident with the ‘Little Ice Age’.”
ANTARCTICA (A long link that didn’t copy well)
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WPN-47G345R 3&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=897221ed8757eec051b4ca7ced2955cf
From the abstract of “Unstable Climate Oscillations during the Late Holocene in the Eastern Bransfield Basin, Antarctic Peninsula”
“The late Holocene records clearly identify Neoglacial events of the Little Ice Age (LIA) and Medieval Warm Period (MWP). Other unexplained climatic events comparable in duration and amplitude to the LIA and MWP events also appear in the MS record, suggesting intrinsically unstable climatic conditions during the late Holocene in the Bransfield Basin of Antarctic Peninsula.”
As Gavin said, look at the rate of increase. Anyone going to tack on the known temperatures to the reconstruction?
SJT: You can’t mix apples and oranges. Known temperatures and proxies can’t be validly analyzed in the same breath. Neither can smoothed and unsmoothed data.
Smooth the current temp record with the same 29 year running average and you won’t see anything special.
The whole point is that we have zero proof that the modern period is anything special. It is only by using anomalous data that we are getting alarmist warnings. Remove the tree ring studies that don’t even match today’s data, and you get a much “calmer” result.
SJT: also, look into the details of Loehle’s study. The SI (Supplemental Information) shows that they (very conservatively) continue to include all 18 non-tree data sets that are available, even though two of them are ridiculously variable (i.e. random). Leave those two out, and the confidence intervals get much tighter on the graph. It’s all about confidence intervals… which the older studies (Mann etc) have never done right, if at all.
Craig Loehle makes a good point:
The absence of a MWP was taken to mean that there were no possible natural factors, therefore recent warming had to be human-caused. The existence of a MWP means that this chain of reasoning is not valid.
It might be worth emphasising that the UK Hadley Centre was first and foremost a political creation and instructed to supply scientfic evidence to show that coal burning was a problem.
Had Thatcher not created this present monster, one wonders what other dogma would be inflicted on us after the events of 1989.
Given that there is so much disputation over AGW, it becomes clear, to me at least, that there is really little convincing evidence either way, and this lends credence to the fact that the whole thing started as a political ploy to counter the Union of Coal Miners decades ago.
The graph above shows units of temperature that no one can actually physical perceive, suggesting that the whole argument is about semantics and really no different to arguing over how many angels could be fit on top of a pin head.
It’s utter baloney and merely an indication of the Peter Principle in which work expands to fit the available time or budget. Quite clearly we have too many scientists quarrelling over how much of an enormous government research budget they get. And what if AGW funds were cut by 90% – What are all these researchers going to do? Most are unemployable in the private sector (principal reason they are on govt pay)so we have an interesting dilemma if it works out that AGW is what it actually is, a political farce with far from trivial implications.
As for the MWP, heaven’s sakes theGreenlanders still cannot farm in areas their ancestors did during the MWP.
Perhaps our erstwhile climate experts here could come up with sound explanations why the planet undergoes periodic ice-ages. Those are the real threats, not warming that is indicated by CO2.
(Incidentally an interesting discussion going
on in the climate sceptics forum where the oceans contain about 98% of gaseous CO2 while the atmosphere 2% under equilibrium conditions. As Tom Seglastadt pointed out some years ago, doubling atmospheric CO2 while at the same time observing the equilibrium partitioning betwee oceans and atmosphere requires more carbon than presently exists at our disposal).
Talk about unintended consequences!
Louis,
Read about the Milankovitch Cycles. That’ll explain you ice ages. Remember that the distribution of continents is important too, so having a large continent at the south pole keeps the southern hemisphere cooler.
Paul – “The absence of a MWP was taken to mean that there were no possible natural factors, therefore recent warming had to be human-caused. The existence of a MWP means that this chain of reasoning is not valid.”
Absolute and complete bollocks. To be able to say such a thing really marks you as someone who is completely biased and closed minded to science. This statement insults the intelligence of practically every living climate scientist. How can you possibly think that scientists that make studying the climate their profession could possibly not recognise that climate change has natural causes?
Do you think that they do not look at the 100 000 year ice core records and see the record of constant climate change when there were no humans?
Only someone who does not really understand the issue of global warming and climate change could write what you wrote.
The scientists that really understand climate change can see that changing climate has MORE THAN ONE CAUSE.
Your statement is completely false. A completely natural MWP is not confirmation that ALL climate change is therefore natural. This is a classic “my dog has 4 legs therefore all 4 legged animals are dogs” fallacy.
You are falsely saying that “the MWP was a natural climate change therefore all climate change is natural”
Climate change has many triggers and causes. One of the proven causes is rising and falling levels greenhouse gases. Humans are emitting billions of tons of these greenhouse gases that are building up in the atmosphere. This has been measured.
To claim that this proven cause of climate change in the past will just somehow this time not cause any climate change is just ridiculous.
Ender – “How can you possibly think that scientists that make studying the climate their profession could possibly not recognise that climate change has natural causes?”
Paul said no such thing. He was summarising very clearly the supposed consensus position on the matter.
You go far beyond mere straw men into straight out dishonesty.
You bog down every second thread with such dishonesty.
Ender, whether or not climate scientists recognise the existence of natural causes for climate change is not the issue here. The Hockey Stick was presented to the public as overwhelming evidence that there had been no global climate change for more than 1000 years until anthropogenic CO2 became a factor. The word “unprecedented”, to describe recent warming, was widely used by those promoting it.
Let’s go with the graph as presented.
So assuming the reconstructions are OK (and gee publishing in something more authoritative than E&E would be good to close on that) what’s the mooted mechanism for the MWP warming ??
So if there an apparent driver – e.g. a solar mechanism or is there an implication that this sort of variation is simply an “inherent part” of the base system variability. If a part of “background variation” we should then be doubly worried about CO2?
MWP might have been great fun for agricultural Vikings tired of raping and pillaging, but civilisations in the Americas and the Chinese may have had other views. And that was prior to 6 billion humans and interlinked global stock markets.
What is the global snapshot of the liveability of the MWP world away from Europe?
And what caused the MWP?
MrPete: “You can’t mix apples and oranges. Known temperatures and proxies can’t be validly analyzed in the same breath. Neither can smoothed and unsmoothed data”
What a mouthful given all the backwards looking reconstructions pasted here.
BTW the one above has to be the worst pseudo thermometer chart I’ve ever had to deal with in anyway. I feel like rubbing it up and down an old fashioned wash board and get some of the fudge out of it.
Luke: This thing is very unconvincing. At least with the hockey stick chart, the error bands converge towards the better known end. Rings indeed!
We were deluded with tree rings too. I’ve been quite happy with the idea, annual growth patterns indicates fertility i.e. sunshine, rainfall and so on both with and without a forest, but not CO2 and temperature levels.
At some point I expect to see discussion about real measurement issues, things like linear and non linear drift and data response to rate change.
Luke, rumbling around in my memory is that during the MWP there were droughts in other parts of the world. I think it coincides with the fall of Angkor Wat for example. Or maybe it was the Mayans?
I could be mistaken so no abuse please.
“What caused the MWP”
“The question as to whether the climatic anomalies associated with the Medieval Warm Period and the Little Ice Age can be attributed to natural climatic variability is explored in this paper”
http://www.springerlink.com/content/u6266q6701747874/
What WMP?
Paul Borg – “Paul said no such thing. He was summarising very clearly the supposed consensus position on the matter.”
This is the quote exactly from Paul’s post.
“The absence of a MWP was taken to mean that there were no possible natural factors, therefore recent warming had to be human-caused”
The absence of the MWP was taken – taken by whom? My interpretation is that it was taken by climate scientists as this is the clear, to me, meaning of this line.
“You go far beyond mere straw men into straight out dishonesty.”
Assuming you actually know what the term straw man means I was not being dishonest so perhaps you can kindly retract this.
braddles – “The Hockey Stick was presented to the public as overwhelming evidence that there had been no global climate change for more than 1000 years until anthropogenic CO2 became a factor. The word “unprecedented”, to describe recent warming, was widely used by those promoting it.”
MBH98 was presented in the AR3 report as the only real attempt to sort out the incredibly noisy proxy ring data. It was one graph that showed recent warming is unprecedented. The six later studies, using a variety of proxies and statistical techniques showed that the original study was essentially correct. This study is the only one that has shown anything different and it has been widely criticised for using selective data and not applying the correct smoothing techiques.
So unless you want to believe this report because it shows what you want to believe instead of the six or so that show otherwise that is your problem.
gavin at January 24, 2008 03:47 PM,
Good God, the CSIRO paper you refer to is 10 years old (published 1998) and relies solely on a computer model.
However the introduction did provide an insight into the author’s prejudices and assumptions when he/she writes:
“The topic of past climatic variability, however induced, is of particular interest given current concerns about climatic change associated with increasing greenhouse gas concentrations in the atmosphere. If substantial climatic anomalies can be identified with natural climatic variability then presumably such anomalies can enhance or counteract greenhouse-induced warming”
In other words, natural variation, if and when it occurs, is a (minor) overlay on the principal cause of climatic variability, yes you guessed it, greenhouse gases and more specifically those resulting from human activity.
In short, to try to erase the MWP and LIA with a computer model, when countless historic accounts as well as (non-treering) proxies referred to above show the opposite, borders on loopy.
Ender – you are the one who constantly talks B*ll*cks.
So, using flawed methodology and biased proxies over and over again by the ‘hockey team’ somehow supports the hockey stick fraud!?
The 18 proxies used by Loehle are peer reviewed and calibrated, from various locations around the world, and have now been further ‘peer reviewed’ by Gavin Schmidt. 2 of the proxies are rather noisey, but still no hockey stick shape.
“if Yamal instead of Polar Urals update are used, you can get Modern Warm Period higher than MWP and vice versa; similarly with Indigirka versus bristlecones; or depending on Mann PC1 bristlecones versus Ababneh bristlecones.”
Why don’t you just admit the truth – which is uncertainty about paleoclimate and the its causes, instead of constantly trying to defend the indefensible?
So Paul I’ve posed some questions accepting the graph for arguments sake? Discussion (for a change) ??
Chrisgo – Barrie Hunt’s (CSIRO retired) paper is dated but does raise the interesting question of how much internal variation in the absence of major forcing changes we might expect? We may or may not accept his answers. The notion of climate moving around by itself because of “Nature” isn’t a very scientific concept.
“natural climatic variability” are Hunt’s words, not mine.
Arr so chrisgo ten years old hey
“In short, to try to erase the MWP and LIA with a computer model”
OK if we use the above graph WPM > LIA = SL change in my book, now where is your evidence for that?
Don’t try n kid me SL wont change with that sort of temp diff, cause we have plenty of evidence of a retreat from the time Tasmania was fully isolated. All you have to do is relate that to some proxy temp chart.
BTW bristlecones don’t wash here.
Luke – I’ve been careful not to present the Loehle reconstruction as definitive, unlike hockey team supporters reaction to the hockey stick. If the paper wasn’t acceptable elsewhere other than E & E, then that is a reflection on the politicisation of climate science, not the paper itself.
We know that there is regional variability in global climate change – we can find evidence of a muted LIA in Australia. Climate change always seems to be most pronounced in the NH.
If I knew all the answer to what drives climate change, I’d probably have a meaningful Nobel Prize – for Physics rather than ‘Peace.’
I would say the Tsonis et al climate shifts paper, plus external solar and galactic factors holds a clue. Past evidence suggests that climate sensitivity to CO2 is low, and that CO2 doesn’t drive climate, but acts as a feedback as CO2 is released form the oceans/absorbed.
If the ‘consensus’ succeeds in shutting down the science as being ‘settled’ – we are less likey to find the answer, or at least take longer to find it.
The currently observed diminishing effect of adding more CO2 to the atmosphere isn’t cause for concern in my view, plus those expressing concern aren’t doing anything meaningful about it – just using it as a wealth distribution tool – where rising emissions are moved from developed to developing countries.
Great post Paul
Past paleo evidence suggests CO2 sensitivity can be high too.
With all the discussion on decadal oscillations and innate “natural” variability on this blog we don’t know if we’re seeing a diminishing effect or not. Let’s not count chickens. Be as conservative as you are on claiming Loehle et al is definitive.
And the E&E stuff does not wash. Get it into Science or Nature. No excuses. Or there is something wrong with it. What do the referee reports say that prevents publishing?
Paul – “he 18 proxies used by Loehle are peer reviewed and calibrated, from various locations around the world, and have now been further ‘peer reviewed’ by Gavin Schmidt. 2 of the proxies are rather noisey, but still no hockey stick shape.”
Yes calibrated but not properly weighted as most of the criticism of this analysis has pointed out and yet you seem to regard this one as the gold standard as it confirms your notions about the MWP.
“Why don’t you just admit the truth – which is uncertainty about paleoclimate and the its causes, instead of constantly trying to defend the indefensible?”
Right back at you mate. If the paleoclimate is so uncertain then you equally cannot assert with any certainty that the MWP was warmer that today as you seem to desperately want.
I am quite prepared to admit the truth that all analysis of the paleoclimate are uncertain because I do not care a pair of fetid dingoes kidneys if the MWP was warmer or cooler than today as whatever temperature is was in that climate change event, mostly confined to Europe, was and independent event not connected to recent anthropogenic warming.
Ender – I am glad we almost agree. As I said:
“In short, the jury is still out on whether the MWP had a global influence or if it was warmer than the Modern Warm Period. Nevertheless, the Loehle reconstruction makes a valuable contribution to the debate and should be included in the IPCC spaghetti graph that replaced the Mann et al Hockey Stick in AR4.”
Paul: There has not enough chat here based on the obvious, too few samples.
Australia has this incredible coastline that intrudes into some of the great oceans of the world. We have plenty of ancient wood and reefs. Climate variability has to be seen first in these regions likewise any sea level change associated with temperature.
To put the current numbers in perspective we sure need to look back at least several thousand years perhaps even ten to twenty but why offer a piece of wood as evidence and for that matter anything else that grew over time without calibrating to say SL max or min of the era in that area ?
Tree rings give us the number of seasons, beyond that its guessing growing conditions.
Examining the grain of polished wood is something I do as hobby and I can say it’s difficult enough to “calibrate” tree to tree from the same patch regardless of era and the same applies to shells and gems. Crystals however should tell us something about longer cycles particularly downunder.
This MWP/LIA stuff is premature.
“It’s all about confidence intervals… which the older studies (Mann etc) have never done right, if at all.”
The older Mann studies were groundbreaking science. For some reason this means he is to be attacked personally and pilloried.
Paul – “In short, the jury is still out on whether the MWP had a global influence or if it was warmer than the Modern Warm Period. Nevertheless, the Loehle reconstruction makes a valuable contribution to the debate and should be included in the IPCC spaghetti graph that replaced the Mann et al Hockey Stick in AR4.”
If you can agree to keep the rhetoric to this more reasonable level then yes I can agree with you. I took exception to your later post not this.
Ender – I wouldn’t be worried about the warmth of the MWP – I would be worried about civilisation busting droughts in the Americas and China. Too much Euro-bias in the romantic aspect of this discussion. Who cares about a few Vikings ploughing the edge of Greenland.
So if there was a global aspect to the period – doesn’t look good to me. And if the explanation is simply internal variation in the climate system with no clear driver we should be even more worried about CO2 spiking things further.
As captain Mannering would say to Jones, you people are in the realm of phantasies.
It was fun for a while to see you people battle on the wind mills, but now it’s just boring monotonous.
Good by. (I’m sure you are going to say good r..)
Ender – I take exception to the hockey stick reconstruction being presented as definitive and flawless – it most definately isn’t.
Hmmmm – so nobody interested in an MWP world then?
Paul – “Ender – I take exception to the hockey stick reconstruction being presented as definitive and flawless – it most definately isn’t.”
How would you know? No study in science is definitive and flawless. The mindless rantings of a mining engineer do not make MBH98 flawed. Follow up studies that used different techniques and different proxies confirmed and extended MBH99. Of course MBH99 was not completely correct – it was the first go at extracting something out of the different proxies. Later studies using and extending the techniques pioneered by Mann, Bradley and Hughes gave us more accurate studies that essentially confirmed MBH99 and gave us a picture of the past climate.
Anyway you have a real case of MWP and Hockey Stickitis. Is this because this is all you have or is it all you understand? Oh I forgot, you also have some totally unproven cosmic ray theory as well.
Ender – if you recall – M&M published a critique in GRL. There were also criticisms made by the NAS panel and the Wegman report. All well documented over at climate audit. More recent developments include the PhD thesis by Ababneh, refereed by Malcolm Hughes:
http://www.climateaudit.org/?p=2504
The hockey stick affair is, and continues to be a disgrace to the name of objective science, plus the antics of those involved, including data archiving reluctance, beggars belief.
Both the CO2 and cosmic ray hypotheses are ‘unproven.’
So it seems like the level of contrarian science including about the MWP is that we don’t know nuttin’ aboout nuttin’.
Wonder why they’re so noisy then.
Paul – “The hockey stick affair is, and continues to be a disgrace to the name of objective science, plus the antics of those involved, including data archiving reluctance, beggars belief.”
The only disgrace is that fairly obscure study into the paleoclimate could be seized on by vested interests and turned into a wedge issue to prevent action on global warming. There was nothing objective to the attack on MBH99 and the eventual ‘criticisms’ only affected the outcome by a few percent. Also if MBH99 was such a disgrace as you term it how could it have been confirmed in such a comprehensive manner by subsequent studies?
Data archiving reluctance. What a load of crap. More like professional scientists not wanting to spoon feed an amateur and unprofessional through an analysis that he should have been able to do himself with the normal data that scientists publish. How typical of the bad carpenter that blames his hammer for his poor work.
“Both the CO2 and cosmic ray hypotheses are ‘unproven.'”
Sorry the connections between greenhouse gases and atmospheric warming has been demonstrated in and out of the laboratory in many different experiments and the scientific literature is filled with papers on the subject if you would care to read them with the blinkers off.
There is absolutely no evidence for a connection between cosmic rays and atmospheric warming other than a few correlations. There is also no experimental or observational evidence that cosmic rays form clouds in the Earth’s atmosphere.
“There is absolutely no evidence for a connection between cosmic rays and atmospheric warming other than a few correlations. There is also no experimental or observational evidence that cosmic rays form clouds in the Earth’s atmosphere.”
Bears repeating.
I bet cosmic rays still spearhead the MWP hunt though
I had said at CA: “The absence of a MWP was taken to mean that there were no possible natural factors, therefore recent warming had to be human-caused. The existence of a MWP means that this chain of reasoning is not valid.”
Nathan made fun of this and then Gavin defends the making fun as if Gavin and nathan are the same person? The paleo record has been used to test the effect of solar activity. Tested against the hockey stick one concludes that the sun has little effect, but tested against Moberg (which looks a little like mine) the sun has more effect. Further, my quote above refers to the many press releases and interviews with the vocal climate scientists who use the lack of a MWP to call the recent warming unprecedented and to dismiss solar activity as having any chance of causing the recent warming.
To
bring the discussion into the modern era.
Solar magnetic activity peaked in about 1987. There is a statistical analysis from
Usoskin et al of the Max Planck Institute showing that the best correlation of
cosmogenic isotopes and surface temperatures is with a 10 year lag.
The usual story is that trends diverged after the mid
1980’s – solar activity declines and temperatures keep rising. If the
solar activity hypothesis is correct, surface temperatures should peak
in about, oh say, 1998. Another way of looking at current influences on global surface
temperatures is with the emergence of a cool La Niña phase of the
Interdecadal Pacific Oscillation (IPO)since 1998. See http://www.bom.gov.au/climate/pi-cpp/FollandSPCZ2002GRL.pdf
for a reasonable introduction to the IPO. La Niña provide a global
surface cooling influence as a result of cool subsurface water
spreading across the central Pacific. Cool La Niña phases of the IPO
bring inceased frequency and intensity of La Niña conditions over 15 to
30 years. It seems possible that the IPO is a dramatic Pacific Ocean
manifestation of global cosmic ray/cloud effects. Regardless, a cool La
Niña phase will moderate global warming over the next couple of decades
and result in higher rainfall over much of Australia. The recent trend
in global surface temperatures is a bit inconvenient for AGW. 10 years
of no global warming? 2007 was the 8th warmest year on the CRU record –
and yes – every year in this century other than 2000 is in the top 10 – although why this is particularly significant escapes me.
Typically, La Niña reduce surface temperatures by
about 0.1 degrees centigrade. The current La Niña could put 2008 out of the top 10.
If the La Niña persists, 2009 could be well down the list. Perhaps somewhere between the top 15 and 20. We live in
interesting times.