From the University of Copenhagen – Niels Bohr Institute
(BTW, the phrase “Past temperature in Greenland adjusted” in the headline is their choice of words, not mine.)
One of the common perceptions about the climate is that the amount of carbon dioxide in the atmosphere, solar radiation and temperature follow each other – the more solar radiation and the more carbon dioxide, the hotter the temperature. This correlation is also seen in the Greenland ice cores that are drilled through the approximately three kilometer thick ice sheet. But during a period of several thousand years up until the last ice age ended approximately 12,000 years ago, this pattern did not fit and this was a mystery to researchers. Now researchers from the Niels Bohr Institute have solved this mystery using new analytical techniques. The results are published in the prestigious scientific journal Science.
The Greenland ice sheet is an archive of knowledge about the Earth’s climate more than 125,000 years back in time. The ice was formed by the precipitation that fell as snow from the clouds and remained year after year, gradually being compressed into ice. By drilling down through the approximately three kilometer thick ice sheet, the researchers draw up ice cores, which provide detailed knowledge of the climate of the past annual layer after annual layer. By measuring the content of the special oxygen isotope O18 in the ice cores, you can get information about the temperature in the past climate, year by year.
But something didn’t fit. In Greenland, the end of the Ice Age started 15,000 years ago and the temperature rose quickly. Then it became colder again until 12,000 years ago, when there was again a rapid rise in temperature. The first rise in temperature is called the Bølling-Allerød interstadial and the second is called the Holocene interglacial.
Temperatures contrary to expectations
“We could see that the concentration of carbon dioxide and solar radiation was higher during the cold period between the two warm periods compared with the cold period before the first warming 15,000 years ago. But the temperature measurements based on the oxygen isotope O18 showed that the period between the two warm periods was colder than the cold period before the first warming 15,000 years ago. This was the exact opposite of what you would expect,” explains postdoc Vasileios Gkinis, Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen.
The researchers investigated ice cores from three different Greenland ice cores: the NEEM project, the NGRIP project and the GISP 2 project. But amount of the oxygen isotope O18 was not enough to reconstruct period temperatures in detail or their geographic distribution.
To get more detailed temperature data, the researchers used two relatively new methods of investigation, both of which examine the layer of compressed granular snow that is formed between the top layer of soft and fluffy snow and the layer deeper down in the ice sheet, where the compressed snow has been turned into ice. This process of transforming the fluffy snow into hard ice is physical and both the thickness and the movement of the water molecules are dependent on the temperature.
“With the first method, we measured the nitrogen content and by measuring the relationship between the two isotopes of nitrogen, N15 and N14, we could reconstruct the thickness of the compressed snow 19,000 years back in time,” explains Vasileios Gkinis.
The second method involved measuring the spread of air with water molecules with different isotope composition in the layers with the compressed snow. This process of smoothing the original water isotope variations from precipitation is dependent on the temperature, as the water molecules in vapour form are more mobile at warmer temperatures.
Temperatures ‘fall into place’
Data for the spread of the water molecules in the individual annual layers in the Greenland ice cores has thus made it possible to calculate the temperature in the layers with compressed snow 19,000 years back in time.
“What we discovered was that the previous temperature curve, which was only based on the measurements of the oxygen isotope O18, was inaccurate. The oxygen temperature curve said that the climate in central Greenland was colder around 12,000 years ago than around 15,000 years ago, despite the fact that two key climate drivers – carbon dioxide in the atmosphere and solar radiation – would suggest the opposite. With our new, more direct reconstruction, we have been able to show that the climate in central Greenland was actually warmer around 12,000 years ago compared to 15,000 years ago. So the temperatures actually follow the solar radiation and the amount of carbon dioxide in the atmosphere. We estimate that the temperature difference was 2-6 degrees,” says Bo Vinther, Associate Professor at the Centre for Ice and Climate at the Niels Bohr Institute, University of Copenhagen.
See film about NEEM icecore project: http://www.nbi.ku.dk/english/sciencexplorer/earth_and_climate/secret_of_the_ice1/video/
FYI, this is what Alley et al. 2000 Grenland reconstruction from GISP2 cores looked like:
“With the first method, we measured the nitrogen content and by measuring the relationship between the two isotopes of nitrogen, N15 and N14, we could reconstruct the thickness of the compressed snow 19,000 years back in time,” explains Vasileios Gkinis.
No, you did no such thing. You speculated. You reasoned. But no one was there at the time taking measures, so anything and everything is speculation.
In the post, there is much that is stated definitively, rather than speculatively. No one knows what was going on 18,000 years ago, and we don’t reliably know how, specifically, the many types of snow might compress to the many types of ice.
If we write our “science” in speculative terms when it is speculative, it keeps peoples’ minds open to alternative process and speculations. And we are more likely to explore more and get closer to the truth.
Dansgaard Oeschger events dont follow CO2 either. Similar spikes of rapid warming followed by cooling are explained by ocean heat ventilation. The only truism that this reveals is those who control present control the past.
The title and slant of this post is unfortunate because it implies that climate skeptics should not recognize achievements by scientists in improving the precision of methods of estimating paleo-temperatures.
The problem of gas diffusion in ice has been long known, so long that it is mentioned in first courses in Quaternary science and also mentioned by skeptics who are up to date with the relevant literature.
The most cursory survey of the literature reveals that the authors of this paper and other groups have been reporting their work on the diffusion problem for some time. This group at the Niels Bohr Institute may have succeeded where others have failed to resolve the anomalies.
As for the comparison with the work of Alley, readers should examine the “Synthesis” section of Richard Alley’s paper, The Younger Dryas cold interval as viewed from central Greenland. Quaternary Science Reviews 19 (2000) 213}226
ftp://mtarchive.geol.iastate.edu/data/2005/stuff/504_papers/Younger-Dryas.pdf
Dr Alley set out multiple explanations for the evolution of the Younger Dryas, only one of which relies on GCMs.
While this paper is very impressive, we need to wait to see the reactions of other groups working in this field.
Fred Colbourne
You rightly say
Yes, and I have repeatedly pointed it out in many places including several WUWT threads.
And supporters of ice core data have always denied it.
Indeed, they have often claimed that proxy ice core data are “direct measurements” because the ice acts like “sample bottles” which enclose air samples over the ice closure time.
Now the global warming scare is collapsing the paper from the Niels Bohr Institute attempts to re-write the ice core data to make it fit their theory.
I distrust their revised ice core data for the same reason I reject the raw data:
i.e. it is presented to fit an agenda and not as a genuine attempt to determine what it indicates.
Richard
thankfully scientists and policy makers reject your rejection
Steven Mosher
No. As usual you are plain wrong.
Scientists accept the reality and politicians refuse a successor treaty to the Kyoto Protocol.
Thankfully most people laugh at your inane one-line interruptions to grown-up discussions.
Richard
Fred, your point is well taken. The climate modelling community hasn’t seemed, for the most part, be able to see that natural variability has shown their models to be in need of serious revision. They were actually surprised, despite abundant evidence, that there are natural cycles of temperatures on earth, in decadal and century timescales (among others).
But that does not mean that there aren’t some good scientists in the field of measurement, and it is harmful to us and to them to put all scientists involved with climate change into the same bin, or purgatory. The Niels Bohr institute has done excellent work in the past, and I see no reason at this point to suspect otherwise here.
Fred Colbourne
‘The problem of gas diffusion in ice has been long known, so long that it is mentioned in first courses in Quaternary science’
Well in public great claims to its unquestioning accuracy have been made.
Help me understand this…..
The new proxies show some correlation with the curve shape from the O18 work, so they are likely a valid proxy for something, but from them are derived a different temperature set, which is the variable we seek.
Question – is there INDEPENDENT work showing that the new measurements are a decent proxy for temperature, or does the idea itself EMERGE from looking for something, in some measurements, somewhere, that better correlates with the previously-assumed causal relationship between CO2 and temperature?
In a lot of Climate work, the second kind of reasoning is employed, without any sort of self-consciousness, or acknowledgement this this might seriously reduce its validity. I’m unsure from my reading of this, which it is. Would somebody who understands it all give an explanation?
As the great (/sarc) James Hansen wrote:
“”Because this result is implausible, instrumentation calibration factors were introduced to reduce the imbalance to the imbalance suggested by climate models…”
http://www.atmos-chem-phys.net/11/13421/2011/acp-11-13421-2011.pdf
So, are they going to toss out all the “flawed” modelling done so far on all the other ice cores from other global locations that has been relied upon so much, and apply this new method?
Totally off topic but don’t know where to ask. What happened to all those CRU emails from the last release? Was there a legal challenge to their release or what?
Actually the CO2 changes were much more abrupt and dramatic at the beginning and end of the younger Dryas than indicated by the ice-core record where all fast changes are smeared out by diffusion:
http://people.su.se/~wohlf/pdf/Steinthorsdottir%20et%20al%202013%20QSR.pdf
http://people.su.se/~adebo/publications/Steinthorsdottir_etal_QSR_2014.pdf
As a matter of fact CO2 concentration increased sharply just before the temperature dropped, and then dropped precipitously once the younger Dryas stadial had begun. The CO2 concentration during the latest Alleröd may have been as high or higher than today and dropped by half in just a couple of centuries!
And before somebody shows up preaching the infallibility of the ice-core CO2 record and the unreliability of stomatal index measurements, please note that the C14 concentration also went down sharply near the end of the Alleröd, proving that there was a massive injection of low-C14 carbon into the atmosphere at this time. By the way this has been known for a long time by archaeologists, since it causes a radiocarbon “plateau” making radiocarbon dates during the younger Dryas ambiguous.
Let us just hope that the current rapid CO2 rise isn’t the prelude to a new younger Dryas stadial….
And there is no real need for snark and indignation. This is a paper describing a changed, and as far as I can judge, improved method of estimating temperatures from ice-cores. It is a moderately interesting paper, but the changes are quite minor, so I’m not in the least surprised that the authors added some CAGW spin. The paper would never have made it into “Science” otherwise.
I note that Richard Alley and the other Grrenland ice core scientists, did not use the typical dO18 temperature conversion formula for Greenland ice core temperature estimates.
They used a calibration based on borehole temperature modelling. This paper continues to use the temperature change that borehole modelling produces. I think the borehole models are just not right.
If the proper dO18 temperature conversion formula was used, Greenland temperatures only declined about 8C in the ice ages (not 20C) and the Younger Dryas only declined about 3C (not 8C). Something approaching the expected polar amplification of up to 2 times, not 5 times that Alley has.
The Antarctic ice cores do not use borehole calibration and are only down 10C in the ice ages, 1.5C drop in the Younger Dryas.
Something to keep in mind.
Compared here.
http://s21.postimg.org/3sy372yef/Greenland_Antarctic_Global_Last_Ice_Age.png
Do my eyes deceive me, or is there a clear counterphase and significant oscillation of Greenland and Antarctica visible in the right hand end of this graph, with Greenland currently in a warmer phase and Antarctica in a colder phase? It’s difficult to track the colors in the increased line density there. The period of this oscillation (if real) looks like it might be around 16,000 years, which is an odd number to see there given the precession/obliquity.
rgb
Related to rgbatduke comment below. Antarctica and Greenland are not in phase in the Holocene maximum or in the rise out of the last ice age as in the Dryas events which were much less pronounced (or non-existent) in Antarctica. (Closer zoom-in only going back to 15,000 bp.
http://s17.postimg.org/itujt0nu7/Greenland_Antarctica_Recovery_Last_Ice_Age.png
DOI: 10.1016/0033-5894(77)90031-X
Get rights and content
Abstract
The Gothenburg Magnetic Excursion in a broad sense ranges from 13,750 to 12,350 years BP and ends with the Gothenburg Magnetic Flip at 12,400−12,350 years BP (= the Fjärås Stadial in southern Scandinavia) with an equatorial VGP position in the central Pacific. The Gothenburg Magnetic Flip is recorded in five closely dated and mutually correlated cores in Sweden. In all five cores, the inclination is completely reversed in the layer representing the Fjärås Stadial dated at 12,400−12,350 years BP. The cores were taken 160 km apart and represent both marine and lacustrine environments. The Gothenburg Magnetic Flip represents the shortest excursion and the most rapid polar change known at present. It is also hitherto the far best-dated paleomagnetic event. The Gothenburg Magnetic Excursion and Flip are proposed as a standard magnetostatigraphic unit.
Very close to the same time frame as the YD event.
Other instances of apparent coincidence in the geologic record:
http://www.physicsforums.com/showthread.php?t=384098
Wow, really interesting thread/comment. The graph that was supposed to support this is a dead link, however, so I cannot see the timing they claim for myself. I’m also puzzled by a possible “external forcing”. The only local strong-ish source of magnetic field is the sun, and its field is orders of magnitude weaker than the Earth’s. Unless, of course, sometimes it self-organizes and isn’t? Which would affect more than the Earth’s field — it ought to seriously affect the Sun’s integrated luminosity as well. Outside of the sun, what? Vagrant “strings” of magnetic super-flux that wander around in the galaxy and that the Earth sometimes collides with? Some sort of dark matter invisible planetoid with a really big magnetic field? Space aliens armed with a pole-reversal vortex weapon? Not easy to think of something that could flip the Earth’s magnetic field “suddenly”, nor is it easy to think of why this would be cooling instead of intensely heating as it occurred.
Not that I “deny” the field reversals, they are well documented. But the wikipedia page on them shows that in fact they are not well-sychronized with much of anything — not mass extinctions, not climate shifts. They aren’t well understood either. Maybe an outside cause, but they really could result from self-organized nonlinear dynamics within the fluid flow interacting with the dynamo, as both model and experient have confirmed.
rgb
Those dates are uncalibrated radiocarbon years and therefore more than a thousand years older than the YD. One must always check which calendar is being used. Older papers usually use uncalibrated dates, more recent ones calibrated.
These researchers couldn’t narrow the Gothenburg reversal down to less than 9 to 14 calendar Ka in the Bering Sea:
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=7&ved=0CFoQFjAG&url=http%3A%2F%2F222.66.161.186%2Fpublicinfo%2Fpdf%2F14dae2fa-cebb-40fc-9575-d22d9bc58b0f.pdf&ei=rvkJVOmRAc3loATX64GgDA&usg=AFQjCNE0CubgkE7bWvvE4KGqQetgqUdQog&sig2=Z2fyyaW6eZ6cP6Hth0ZkBQ&bvm=bv.74649129,d.cGU
CHINESE JOURNAL OF GEOPHYSICS Vol.56, No.5, 2012, pp: 240–1
GEOMAGNETIC INTENSITY AND DIRECTION FOR THE LAST
14 KA RECORDED IN THE CORE FROM THE BERING SEA
It cites studies in other locations.
The conducting inner core is strongly coupled by Lorentz forces to the circulating liquid outer core. Differential rotation between two is low but variable, advancing or retarding may be the key. Important point here is that the inner solid core is lopsided, and is in the permanent state of flux. Currently western hemisphere is solidifying and the eastern hemisphere melting, enhancing flow in the east, where as it happens is greater strength of the field. Once the asymmetry becomes to great, inner core might slightly re-align itself, resulting in a magnetic jerk, the strongest one in recorded history (since 1700) peaked around 1930, but there were 2 minor one since and another may occur soon. If a jerk is too severe differential rotation vector may reverse its direction, resulting in a flip of magnetic polarity.
I think how dramatic a climate effect may or may not be depends on how the candidates for climate change phase together. Also the circumstances at the time they phase together.
Those candidates for my two cents worth being
solar variability and primary and associated secondary effects
strength of the earth’s magnetic field which will moderate solar effects
initial state of the climate -how close to threshold climate is from glacial versus inter-glacial conditions
which will greatly moderate GIVEN solar effects and earth magnetic field effects
milankovitch cycles where is earth in reference to these cycles.
Another factor which is sort of way out is what is the concentration of galactic cosmic rays in the vicinity of the earth (within 6 light years) when solar effects/ geomagnetic effects may be taking place. This might have a moderating effect on their effectiveness.
Geographical positions of land versus oceans and the ice dynamic at the time.
The oceanography literature shows that the Bolling-Allerod first warm spike and the following Younger Dryas vool interval were triggered by Antarctic events, particularly an ice sheet collapse, in the context of the inter hemisphere bipolar seesaw. Note that the Antarctic started steady warming about 22kya, ling before the NH. In the recent rather acrimonious thread on the (flawed) YD impact hypothesis I set out in detail this series of events.
Specifically it was Antarctic intermediate water resulting from the Antarctic ice sheet collapse 2ky previously that stopped the Atlantic Meridional Overturning Circulation and started the YD (the ocean has a long memory).
What happens when the AMOC stops? Cold supersaline water in the Arctic – near Greenland – which would have sunk with the AMOC to form deep water, does so no longer. This saline water hanging around and not sinking would cause the salinity at the sea surface in the North Atlantic to rise.
Now is it possible that increased N Atlantic salinity due to stopped downwelling would exaggerate the effect of low water temperature in decreasing evaporation? And could this cold super-salty water give a precipitation signal to the O18 isotope method equal to that of water with “normal” salinity but a lower temperature?
In short, could the increased N Atlantic salinity due to a stalled AMOC slow evaporation thus giving an artefact of lower temperature?
“””””….. We estimate that the temperature difference was 2-6 degrees,” says Bo Vinther, Associate Professor at the Centre for Ice and Climate at the Niels Bohr Institute, University of Copenhagen……”””””
I really liked this part of the new data. It’s very special. It confirms the obligatory three to one ratio of uncertainty range that is mandatory in peer reviewed climate papers.
But note the researchers are cautious about what they have proven to be the new correct result. They say: “We estimate….”
So their 3:1 ratio is just an estimate, it is not a firm prediction; excuse me, that’s observation not prediction. When you can’t see something better than 3:1, there is no point in trying out prediction, or even projection; you can’t even do observation.
But at least we now know that all of that Antarctic ice core data that depends on 18 O proxies, is also just junk.
Big Minds
On this site there are several big minds. If you are not mentioned please assume I missed your post’s.
We have RGBatDuke, we have Stokes, we have Mueller and by proxy, “Proxy” what a word in this field, Mosher. Courtney has his own mind, high praise in my world, as does Anthony Watts our host, himself!
Stokes, Mosher and by proxy Mueller, seem to live for the contrapositive, a valuable function, which unfortunately never is able to contribute any information. Apparently Mosher and Mueller are proxies for each other, never tried it, hope I never must.
Many many, too numerous to mention, post to insist on traditional methods to report DATA, such an important word on this site. Data is, so simply defined, the NUMBER recorded from the INSTRUMENT. It goes without saying, Mosher, Stokes, that DATA cannot be ADJUSTED, for after this procedure, it is no longer DATA.
RGBatDuke is the most important man on this site.
Professor Brown is the most scientific man it has ever been my pleasure from whom to hear, not counting Professor Smith at Michigan who taught me Thermodynamics. That would be Eugene Smith for those of you scoring at home. Professor Wang, not so bad either.
Climate Science is not science. This is the most important message from this site. Climate Science is pseudo-science, as repeatedly pointed out by Professor Brown, who repeatedly points out the Absence of ERROR ANALYSIS! Real Scientists would sooner die than fail to publish the Error Analysis.
Professor Brown told me to stop banging on Stokes, so I did. Soon after, Professor Brown banged on Stokes harder than I ever had, or could have.
Stokes is the contra-positive to Brown. Stokes seems to have his own mind, makes many correct points, and yet always, always, is disingenuous. Mosher does this too, but not as well as Stokes. Stokes and Mosher, getting paid to do what exactly???
Mueller has been published in the WSJ as have I, but Mueller more than once. Mueller is the most subtle man involved. He is smart enough to have his name mentioned in the MSM more than once, and at the same time has slain Mann publicly. Mueller, what is he up to???
Big Minds, my favorites, which are telling the truth???
“So the temperatures actually follow the solar radiation and the amount of carbon dioxide in the atmosphere”.
If the O18 data “inaccurate” they are so everywhere.
And are they saying that there’s a time lag, proving again that CO2 is not a climate driver?
”
rgbatduke
September 4, 2014 at 2:37 pm
”
Some interesting comments!
Most of what we see of ocean currents and the like is simply moma nature’s heat transfer efforts. As long as there is a termperature difference, there will be a way for heat to transfer.
The speculation of magnetic field variations and other possibly cyclical variations like M-cycles do not seem to me to be the major causal effects.
Crucial to the whole issue is albedo. For Earth, our oceans lower the surface albedo to significantly lower values than objects like the Moon and Mars. Most of the albedo is clouds and atmospheric factors and these are likely highly sensitive to influence. Earth’s effective radiating T is about 255K. Even though Venus is significantly closer to the Sun, its effective T is more like 180K due to its total cloud cover.
It would seem that catastrophes like large impactors and mega erruptions are capable starting a glaciation period which would then short circuit a cloud feedback setpoint control system for T. Fresh snow gives high albedo but as time goes on, it reduces down due to soot from fires, erruptions, small meteroids, compacting, etc. so that eventually, we get melt water pools whose albedo becomes minimum, eventually pulling us out of the glaciation period. Also, substantial glaciation reduces precipitation so even sublimation can start to take effect. Catastrophes could also enter in but those are best left to those areas that might probably need them.
The cloud & atmospheric factors provide a real wild card since these can be affected by many internal and external factors. These can provide a massively sensitive mechanism with some very serious effects for apparently very small variations.
The scientific method: “Make a hypothesis, plan a controlled experiment, do the experiment, record the observations. Look for possible errors, if such are present, try minimizing them and do the experiment again.”
Accept the result. If the hypothesis fails, our assumtion was wrong.
The dogmatists method: “We have some pre-concieved theory that the world works in this or that way. The results from an experiment has falsified the theory. Now lets try and change the conditions for that experiment, so that the results better fits our misconceptions, and by that falsify the results from the previous experiment.”
You’re right, guys, this is not science.
Thank You again, Anthony Watts.
In science, we do not start with the conclusion, and conduct experiments to prove the conclusion. We start with a guess and and open mind, conduct experiments and accept the results.
As You all know, the Pope did NOT see it, only Galileo Galilei did.