Read on for a new Josh cartoon.
What’s wrong with this image? Well if you are part of The Team (RealClimate and friends), it goes against everything you’ve been publishing. You want the Medieval Warm Period to disappear, and you want a hockey stick at the end showing “unprcedented” warming. The shape below just doesn’t cut it when that’s what you are researching selling.
On the left is temperature in °C, on the X axis, years, with labels from 0AD to the year 2000.
Images like the above don’t sell. With a clear MWP and no hockey stick, there’s no alarm, and no $$ coming in for “further studies”. In the Wake of the Gergis et al retraction, Steve McIntyre notes that one of the “screened out” datasets just happens to be the one with the best resolution and the greatest duration – the Law Dome Oxygen 18 data set (from Antarctica). He writes:
An annual version for two millennia was provided to Gergis (who screened it out.) delD and O18 are closely related and presumably the unarchived del D series will look somewhat similar.
For those that don’t know what this data represents, here’s a quick primer from Wikipedia.
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Oxygen isotope ratio cycles are cyclical variations in the ratio of the abundance of oxygen with an atomic mass of 18 to the abundance of oxygen with an atomic mass of 16 present in some substances, such as polar ice or calcite in ocean core samples. The ratio is linked to water temperature of ancient oceans, which in turn reflects ancient climates. Cycles in the ratio mirror climate changes in geologic history.
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Connection between temperature and climate
The 18O/16O ratio provides a record of ancient water temperature. Water 10 to 15 °C (18 to 27 °F) cooler than present represents glaciation. As colder temperatures spread toward the equator, water vapor rich in 18O preferentially rains out at lower latitudes. The remaining water vapor that condenses over higher latitudes is subsequently rich in 16O.[2] Precipitation and therefore glacial ice contain water with a low 18O content. Since large amounts of 16O water are being stored as glacial ice, the 18O content of oceanic water is high. Water up to 5 °C (9 °F) warmer than today represents an interglacial, when the 18O content of oceanic water is lower. A plot of ancient water temperature over time indicates that climate has varied cyclically, with large cycles and harmonics, or smaller cycles, superimposed on the large ones. This technique has been especially valuable for identifying glacial maxima and minima in the Pleistocene.
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McIntyre adds:
Oxygen isotope series are the backbone of deep-time paleoclimate. The canonical 800,000 year comparison of CO2 and temperature uses O18 values from Vostok, Antarctica to estimate temperature. In deep time, O18 values are a real success story: they clearly show changes from the LGM to the Holocene that cohere with glacial moraines.
On its face, Law Dome, which was screened out by Gergis and Karoly, is an extraordinarily important Holocene site as it is, to my knowledge, the highest-accumulation Holocene site yet known, with accumulation almost 10 times greater than the canonical Vostok site. (Accumulation is directly related to resolution: high accumulation enables high resolution.) The graphic below compares glacier thickness for some prominent sites for three periods: 1500-2000, 1000-1500 and 0-1000. its resolution in the past two millennia is nearly double the resolution of the Greenland GRIP and NGRIP sites that have been the topic of intensive study and publication.
Given the high reliance on O18 series in deep time, one would think that paleoclimatologists would be extremely interested in a publication of the Law Dome O18 data and be pressuring Tas van Ommen on this point.
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But despite the apparent opportunity offered by Law Dome, there has been virtually no technical publication of a high-resolution O18 or delD isotope series.
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A Climategate email shows that Phil Jones asked about the omission of the Law Dome series from the IPCC illustration in the AR4 First Draft. I asked the same question about the AR4 Second Draft. They realized that the Law Dome graphic had an elevated medieval period and thus, including it in the graphic would – to borrow a phrase from the preparation of AR3 – would “dilute the message” and perhaps provide “fodder to skeptics”.
Read the whole report at Climate Audit here
The Team keeps trying to bury this stuff, and Climate Audit keeps digging it up:
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Its high time these people were sent letters as to why their employment should continue at the University of Melbourne at taxpayers expense
The superlative of ‘high’ is ‘highest’.
Nick Stokes says:
Not so clear to me. As I recall, d18O correlates negatively with temperature.
You obviously didn’t read the article or you would have read the sentence that says just that. “Water up to 5 °C (9 °F) warmer than today represents an interglacial, when the 18O content of oceanic water is lower”
The 18O/16O ratio provides a record of ancient water temperature.
[b]No, it does not![/b] A sad mistake, started with Willy Dansgaard and there are several studies finding contradictions with that supposition.
For meteorologists it’s easy to explain where the error is. In the textbooks and several studies you will find that the major drivers for 18O fractination, d18O is the temperature at condensation and the raining out or Rayleigh processes.
So what is that cloud temperature? Isn’t that the dewpoint, which is primairely a function of absolute humidity. And of course, most of the time there is a correlation between temperature and humidity, but not always as in the desert.
But the rayleigh process may even be a bigger problem, if the prevailing weather patterns change for some reason, as everything was changing between glacials and interglacial periods, the rain out could also change considerably.
“As I recall, d18O correlates negatively with temperature.”
I recalled coral numbers – I was wrong here.d18O in ice goes the other way.
Nick Stokes says:
June 13, 2012 at 12:39 am
“With a clear MWP “ Not so clear to me. As I recall, d18O correlates negatively with temperature.
You are of course correct Nick. Now would you like to have another look at the labelling of the y axis and post back with your revised interpretation.
Nick Stokes says:
June 13, 2012 at 12:39 am
Not so clear to me. As I recall, d18O correlates negatively with temperature.
Note the y axis on the graph. Decreasing d18O concentrations.
“Not so clear to me. As I recall, d18O correlates negatively with temperature.”
Really?
http://eesc.columbia.edu/courses/ees/slides/climate/observed.gif
This concurs with an ice core temperature reconstruction from the Penny ice cap on Baffin island in the Arctic.
http://c3headlines.typepad.com/.a/6a010536b58035970c016765a161db970b-popup
This graph (unlike many played with by many) speaks for itself, in loud voice.
Although I disagree with Steve’s remark about people being “entitled” to respect, in this case Steve McIntyre does deserve respect. Bravo.
P.S.
Those who are so fond of Andrew Rivkin’s “balanced reporting” should ask him to investigate, why this most important data is being “screened” (disappeared) by ever-so-honorable “scientists.”
Bet you $100 he won’t bother.
I don’t like to criticise Josh’s work but, the bull-dozer with climate audit on the side appears to be burying the reports not excavating them. Perhaps it should have been labeled The Team
Nick Stokes on June 13, 2012 at 12:39 am said:
Not so clear to me. As I recall, d18O correlates negatively with temperature.
– – – – –
Nick Stokes,
Which makes the charts shown in the post correctly indicating the dO18 relationship with temperature . . . so, yes there was indeed a MWP in the SH.
John
The data had to be there if enough effort was made or the correct site chosen for the best resolution. The graph showing temperature from the Cambrian shows the Ordovician ice age when the atmospheric CO2 content was in excess of 6000ppmv with some data showing 8000ppmv. What happened to the GHG theory then?
Good, interesting post.
Nick Stokes 12:39…
so there was an ice age in the MWP and a warm period following it, now to be known as the Little Warm Period??
Nick Stokes:
Write to Michael Mann.
He is a specialist in turning data graphs upside down.
And he will feel your pain (for a fee).
Stokes: You are wrong. The IMAGE has a clear MWP. Easy to see.
But if you believe that the science behind the image is wrong, show which part of the Wikipedia explanation above is mistaken.
Nick Stokes says:
June 13, 2012 at 12:39 am
“With a clear MWP “
“Not so clear to me. As I recall, d18O correlates negatively with temperature.”
The graph is labelled d180 but the units are degrees C, with temperatures increasing upwards. Therefore the graph does show a clear MWP.
Chris
Looks to me as though an arbitrary axis was inserted around -21.5°C & flipped the graph at that point to show continued warming as opposed to moderate cooling since the MWP! You have to admire their sheer treachery & deceit all for a fast buck & a pension plan!
The Law Dome is in Antartica – southern hemisphere – which has a somewhat different climate to the northern hemisphere – so I would hesitate to use Law Dome alone to project a global picture of the past. Vostok shows something different .
Also, as Nick Stokes says, d18O correlates negatively with T. – so how does the graph show a medieval warm period? Please clarify someone!
To clarify,
Surprisingly, nothing on the d18O data from the Taylor Dome has been published for the Holocene. Data for earlier periods has been published.
By the way where is Lazy Teenager?
This Law Dome graph needs to be strongly challenged.
It needs to be picked apart in detail.
Every assumption must be clarifed and tested.
It must be proven to be robust not just because we want it to be but because it is robust.
Because if this proxy does show what it looks like showing then the AGW hypothesis is disproven.
CO2 sensitivity can’t be high enough to cause a problem if the current tempertaure response is well within natural variability.
This is either a rightly discarded false proxy or the end of the scare.
Nick Stokes,
“As I recall, d18O correlates negatively with temperature”
You may want to check out the numbers, and in which direction the go up/down on the axis to the left ..
AndrewMHarding, you are mixing two issues. There was the empirical issue of circles versus ellipses and the formal issue of the centre of the system. Because all motion is relative, it does not matter from which point of view a system of moving bodies is described. Bruno was burned at the stake because of the formal issue. Perhaps he was the only one. Many people got this treatment because of their Protestant rebellion against the Old Church and State. It is an historical myth that scientists shared their cruel fate. You better should explain that AGW is an empirical issue because it makes wrong predictions (like the hot spot, etc.).