Past temperature in Greenland adjusted to fit new theory

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 revised Greenland temperature history (black curve, grey uncertainties) for the period 18,000 to 10,000 before present. This temperature history is based on temperature interpretation from nitrogen measurements (green curve) and O18 diffusion measurements (red curve). The blue curve is from a previous study, based on nitrogen measurements. Credit: Niels Bohr Institute

The revised Greenland temperature history (black curve, grey uncertainties) for the period 18,000 to 10,000 before present. This temperature history is based on temperature interpretation from nitrogen measurements (green curve) and O18 diffusion measurements (red curve). The blue curve is from a previous study, based on nitrogen measurements. Credit: Niels Bohr Institute

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:

Alley et al. (2000) Greenland

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Bart

Well, now that they’ve found a proxy which gives them the answer they want, they can stop looking. Classic confirmation bias.

JJ

Exactly.
If they see data that differs from their desires, they change the data out until they find some that fit the need.
Data that fit the desires are not questioned.
No different than accepting tree ring temps that fit the political narrative, while replacing those that don’t with the instrumental record. Niels Bohr institute has discovered Mike’s Nature Trick.
This is not science.

latecommer2014

Are you saying temperature follows CO2 rise? Theat would be “unprecedented “!

A fundamental requirement of scientific investigation is that you choose your methods before looking at the data. Otherwise you end up cherry picking your methods to confirm your own unconscious bias. Since bias is unconscious, you the researcher are not aware of the error you have made.
The problem is that many of the “soft” sciences do not recognize this type of error as being an error. As a result their findings are more about pseudo science than science.

jim

Peter,
Any paelo proxy is at the mercy of entropy. The climate is the state of the matter of the biosphere, some of the matter of the oceans, and most of the matter of the atmosphere. A very large amount of matter. After 15,000 years of entropy, almost almost all of the information of the state of that matter, the state of the climate matter 15,000 years ago, is lost. The quantity of matter in the world, matter that was climate and not rock, the quantity of climate matter in the world that is in the same state as it was 15,000 years ago, is vanishing-ly small. The inferential extraploation that is needed to ‘recreate’ the state of the all of the climate matter, 15,000 years ago, is an academic career. It is fun and it is entertaining, but it is not close to being “valuable” enough to to make international policy.
It is “valuable” to you who do it, and its development is “valuable” to your careers. But it is irrelevant to the present overcrowded, overarmed, hyperconflicted world.
So: No, it is not valuable to all of the rest of the world’s population. Sorry.

jim

Tree rings, speliotherms, ice layers, silt deposits, pollin and bio indicators are a very very very small quantity of all of the measurable matter that is the climate. Yes, it’s a big amount of measurements, compared to speculating based on nothing. But as a measure of climate, it is nothing. Suggest that today, you will tell us the climate today, by presently measuring a few layers of snow, a few tree rings, a few stalagmites, and a few isotope ratios. What measure of the climate today could you get from those? No more measure than you can get from those of 15,000 years ago… Not much.

jim

When all of the reconstructive work is done (hockey stick et al), all that comes out is global temperature, or hemispheric temperature. So the proxi climate is one number for everything, or one number for half of everything.

LeeHarvey

Well… at least they figured out the correlation part.
Now if only they could nail down that pesky correlation/causation conundrum, they might get somewhere…
‘Course they’d still only have a model for Greenland, not the whole world.

Shawn

They saved Global Warming!

JimS

I smell another Nobel Prize winner here.

Are they saying that in Greenland temperature follows CO2 even though everywhere else it is the other way around?

Latitude

yep

Fred Nicol, Hoover, AL

The logic seems Procrustean. Said another way, if you torture the data long enough it will eventually say what you want it to say

What now? Let me tell you what now. I’ma call a coupla hard, pipe-hittin’ climate scientists, who’ll go to work on the data here with a pair of pliers and a blow torch. You hear me talkin’, data? I ain’t through with you by a damn sight. I’ma get medieval warm period on your ass.

harkin

“Mark and two Cats has encapsulated the duty of every government-funded, policy-driven scientist.”
FYP

In other news, John Kerry today said that when it comes to Climate Change, we should all forgot about the silly “Separation of Church and State” stuff.
Secretary of State John Kerry said it was the United States’ biblical “duty” to confront climate change at home and abroad in “Muslim-majority” nations during a speech Wednesday..
“Confronting climate change is, in the long run, one of the greatest challenges that we face, and you can see this duty or responsibility laid out in Scriptures clearly, beginning in Genesis. And Muslim-majority countries are among the most vulnerable. Our response to this challenge ought to be rooted in a sense of stewardship of Earth, and for me and for many of us here today, that responsibility comes from God,” he continued.
http://freebeacon.com/issues/kerry-scripture-says-u-s-should-protect-muslim-countries-against-global-warming/
Anyone still think this issue has ANYTHING to do with “science”??? Anything at all?

DirkH

The speechwriter for the Administration is probably an implementation of
http://en.wikipedia.org/wiki/Mark_V_Shaney
You feed in source text, it outputs gibberish that superficially looks like human sentences. Source material must have contained something about the Middle East carnage and something about Global Warming. And a sunday sermon.
So:
We can use Kerry as a proxy to determine the kind of source material the WH uses.

Mac the Knife

Anyone still think this issue has ANYTHING to do with “science”??? Anything at all?
No. In addition, John Kerry has ‘nothing to do with science’ either.

Betapug

Hillary Clinton on one of her trips to China, (apologizing and imploring the Chinese not to repeat America’s mistakes), explained that the opposition to confronting ” Global Warming” was mainly from Christian fundamentalists but she thought that they could “get them” with the “stewardship of the earth” thing.

kcom

It’s a wonder they can tie their own shoes if that represents the level of sophistication of their thinking. How can someone possibly be that out of touch, both in the diagnosis of the problem and the ham-fisted strategy to “get them”.

rah

Would this be the same John Kerry that predicted in October of 2009 that the Arctic would be “ice free by 2013”? http://www.huffingtonpost.com/john-kerry/we-cant-ignore-the-securi_b_272815.html

latecommer2014

Would this be the same John Kerry that filmed his glorious retake on shooting a 13 year old “Vietnam Cong” when he was with the Swift Boats in Nam for later political use. The man was scum then ( ask any of us that knew him then) and has stayed consistent since then.

rah

No argument here.

Trying to inflate the paper by using Bohr’s name? Niels Bohr practiced real science and did not need to be a name dropper.
If you’re so set on the value of the paper why aren’t you quoting relevant data and the ‘new’ flashy analysis.
Or, perhaps you can explain why these characters can ‘prove’ CO2’s impact on temperatures using paleo ice cores but are unable to demonstrate any modern CO2 impacts?

Mac the Knife

Past temperature in Greenland adjusted to fit new theory
Translation:
We didn’t get quite the curve we wanted on the AGW Etch-A-Sketch…. sooooo we just shook it up and drew another one! Simples..

Bob Zorunkle

So, they are adjusting again…. What else is new? In any event, the last 1000 years, according to their new adjusted figures, looks nothing like the Mannian hockey stick, so at least we can agree on that.

DirkH

So they destroyed O18 as a temperature proxy.

That is the unstated implication. At least it is “inaccurate”. So what does that do to certainty? Nothing. The certainty is in the general, not the detail: 1C or 4C. All the same, react the same.

JJ

So they destroyed O18 as a temperature proxy.

Yes, but only situationally. O18 is still fine to use, when doing so produces the desired results.
Kind of like how treemometers need to be replaced with other datasets when they break the blade of the hockey stick, but are AOK for the haft …

ezeerfrm

“We have always been at war with Eastasia”

LeeHarvey

I think that at tomorrow’s Two Minutes Hate, I’m going to focus on Anthony’s parents and their failure to mold him into a goodthinking Party member…
REPLY: my first thought here was to tell you to go ” ” yourself, and put you in the permanent troll bin. Both of my parents died prematurely from smoking related effects, and I have a hearing loss because of complications of 2ndhand smoke effects. So, it is a touchy subject with me. I assume now that you are being sarcastic, but please don’t raise the subject again – Anthony

LeeHarvey

My apologies – I only meant to compare you to Emmanuel Goldstein, as you are the embodiment of the anti-Party (anti-alarmist) movement for some. I was picturing your face on the telescreen when the warmists have their daily Two Minutes Hate. I made a ham-fisted joke in expressing the metaphor, and I am truly sorry to have broached a touch subject.

I am very disappointed. Never could I imagin that Niels Bohr institute of all, doesn’t understand that they are presenting themselves as fools. Have they forgotten the basic natural laws for water cycle? Is it really possible that they don’t know WHY the ice core examples doesn’t give them correct information re. CO2 in the past? I think it would have been good had they studied the analyse methods of last 30 years in archaeologic field analyse methodology and technology.
* Water in all form tries to reach the lowest point possible.
* In ice core there are differences in structure as well as in density not to mention the simple fact that erosion, wind-/water-/temperature change each period’s surface.
* the “heavier” structure, such as soot, vulcano ashes and other particles from nano up, due to gravity and so on “falls” quicker.
* Ice core aren’t reliable in anyway on same level as sediment layer which btw not always are as well. (Depending on many different factors)
I never thought Niels Bohr Insitute to present such bad level of Theory of Science usage. Sorry. But I had to say this. Mathematic models, computers or not, doesn’t hold water if one don’t take ALL needed factors for a premise to be true into consideration.

Bohr is spinning in his grave.

SasjaL

This is what happens when scientific institutes transforms into political ones …

Result is what we seen in the “paper”…… 🙂

latecommer2014

I agree at 97.5%

That’s ok. I wouldn’t like a copy of myself walking around somewhere…. 🙂

joelobryan

And the Science Mag editorial staff, led by Marcia McNutt, bought into it. Thus implicitly the AAAS is as guilty of political corruption of science as the Bohr Institute. But we already knew that.

Eliza

I thought it was established that rises in atmospheric CO2 FOLLOWS rises in atmospheric temperature? or am I wrong? LOL

LogosWrench

When all else fails manipulate the data.

Have a real real good look at Alley 2000
Notice how snow accumulation and isotope temperature show a corrolation tht seems too good to be true.
http://wattsupwiththat.files.wordpress.com/2013/02/alley2000.gif
Isn’t there anybody frowning and thinking, if they are so incredibly alike, aren’t they just the same?
Consequently, could the isotopes be a proxy for moisture/aridness/precipitation rate, rather than for temperature?

cicero

If the temperatures at various points in time were high around the world, then there would be more water in the atmosphere, and so more precipitation including snow.

But how about the sahara? Also it can be relatively warm and still dry on an ice sheet.
Wouldn’t this strong corrolatlion be a reason to revisit the research after the exact process of how isotope ratios are formed in the complete hydrological cycle?

cicero

“But how about the sahara? Also it can be relatively warm and still dry on an ice sheet. ” When exactly ? e.g. during a time when the earth is colder, the ice sheet and the world generally will be ‘dryer’.

Robert B

There is a large difference in the amount of 18O in snow and rain. The rain fall in Greenland is about 0.2m in the North and 0.9m in the south of Greenland.
The trends in the curve might be fine but the actual temperatures might need to be taken with a pinch of salt.
Now the colder it is, the less rain there is and the less compressed ice due to rain. If you take the proxy for ice fluffiness seriously, then they have shown that there is less rain when its colder and not a different temperature profile.

Claude Harvey

Regardless of the actual temperature profile, the implication that atmospheric CO2 drove temperature rather than the other way around has never been established to my satisfaction. Does this revision do anything to clarify that issue?

DHR

Cant see much difference myself. Temperatures rose, fell and rose again at about the same time in both but the new chart suggest the lowest ‘tween-the-rises value was about 2 degrees less cold. How that is news escapes me.

Tom O

Picture all there is to know about science as the Pacific Ocean. Now picture all that man THINKS he knows as the Atlantic Ocean. Now take that bucket your kid uses in his sand box and fill it with water. That bucket will actually, in scale, represent what man REALLY knows about science. I’ve said it before, proxies are guesses, not data. Useful in trying to understand the truth, but they do not represent truth any more than does all those global climate models represent the probably climate. Like proxies, they are guesses, not facts.

hunter

The method seems dubious. If things are freezing, they are already cold. I find it difficult to see how they can use such an indirect proxy and claim such levels of accuracy. It also seems that the paper shows CO2 is *not* the big driver.

Svend Ferdinandsen

My interpretation of the Alley picture is, that snow accumulation increases with temperature, so what is the problem. Correlates with the fact that the Summit station needs to be raised now and then.

Mihail

The 2 proxies they are suggesting, even if we assume they are accurate, are very local. The O18 proxy is more global in reach than their methods. Low O18 shows that the evaporation happened very far away from Greenland, ie the ocean that surrounds the island was way too cold to support evaporation. Greenland is a frigid place no matter the climate at 45 degrees latitude. Also colder global climate means fewer precipitations in Greenland, we ca easily see that from the last plot in the article (that itself could be a better proxy for the global temperatures than the O18 itself). During glacial periods, the ice sheet should be less thick than during warm period (the thawing of the ice at the bottom is independent of the global climate as thick ice is a good insulator). This means that the surface of the ice sheet is at a lower elevation allowing for higher local temperatures.

pat

[SNIP !!! Pat, when will you learn to stop posting OFF TOPIC ARTICLES??? You’ve been warned several times. This article is about Colorado, not Greenland. Do we have to ban you to get this point across? – Anthony]

pinroot

Maybe you meant “This article is about Greenland, not Colorado”? Otherwise, I’m confused.

Katherine

I think Anthony meant the article pat posted, which got snipped. Since it’s not about Greenland, it’s off topic. By the way, Anthony, thanks for blocking pat’s indiscriminate thread bombing.

Latitude

“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”
====
So we will just charge ahead assuming we have the correct CO2 and solar proxies…and we know what they do.
bad science is self replicating

Greg Goodman

No, it’s not speculation

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

If the data tells you something other than what you “expect” you change you expectations, not the data.
If dO18 is not longer a reliable proxy a lot of work goes out of the window. That requires solid justifications, not just averaging with a second proxy.
There is clearly a very significant variation that caused this reversal that can not be accounted for by banal relationships to CO2 or solar. Unit that is explained and understood there is not reason that 12k BP being marginally cooler than 15k BP should be a problem.
The problem is refuting the evidence because it does not fit some trivial hypothesis that expects simple linear correlations with _supposed_ drivers of climate.

cba

LOL. Grants are essentially never given to duplicate an experiment. Publishers and reviewers tend to reject papers about duplicated experiments because “it’s already been done”. Peer reviewed publications have nothing to do with being part of the scientific method. Also, the review of a proposed publication is not duplicating an experiment, it’s a simple check to make sure that the article content is somewhat relevent to the field and is not full of obvious problem (and that does not seem to even be working in numerous cases).

Duster

The “cold period between the two warm periods” is the Younger Dryas, the cause of which is being debated constantly. In fact, a tiny bit of searching will reveal that there are serious operators out there who believe that they have proved that the YD is due to an impact event. If so, then it’s occurrence would be causally unrelated to the Wisconsinan glacial epoch and its ending. It simply happened as the epoch was ending. So what we really see is a regime change between the “real” glacial and the Holocene. That change effects basic relative concentrations of isotopes. The YD did not effect these, it simply made things colder for a (geologically) short time span.

So, seems to be a very strong correlation between snow accumulation rates and warming/temperature. Thus, are snow accumulation rates rapidly increasing?

“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”
That would imply the Younger-Dryas did not occur. What is next???? …. a dry Doggerland until man started using fossil fuels?

Mark Lee

I’m not a scientist, but just plugging this in with recent news makes me come to a different conclusion. Specifically, recent articles say the cause of the Younger Dryas cooling and extinction have been determined. The widespread layer of microdiamonds indicate a cosmic body impact, i.e. asteroid or comet. That caused a rapid cooling for approximately 1,200 years, during which most of the North American megafauna became extinct and the Clovis culture disappeared. Since CO2 levels lag temperature changes, this seems consistent with the data. Sudden cooling, but higher CO2 consistent with the prior warm period.

asybot

Mark, is there any info as to the effect of the recent meteor that skimmed and broke up over Russia as to the amounts of particles left after the event. If so where could I find it?, Thanks

Duster

The scales would have been profoundly different. Events like that over Russia are much more common than one would normally think, because most happen over the oceans. If you dig into it, there are recordings, most by nuke test monitoring sites that identified much larger blasts than the Russian event. If the YD was really caused by an impact event, it would have been several orders of magnitude greater than any recent event.

Also, given what appears to be a strong correlation between snow accumulation rates and temperature in their graph, it would suggest they have not properly accounted for the amount of compaction that occurs as the depth of their sample increases. The slope temperature as a function of compaction is opposite of that as a function of depth for the past 10,000 yrs.

Alarmists may depict glaciers flowing like a river towards the seas, in a rush to make waves on New York and Washington. By 2000 according to Moynihan http://www.nixonlibrary.gov/virtuallibrary/releases/jul10/56.pdf.
Paradoxically they may at the same time believe the glaciers to be perfectly static for tens of thousands of years. Never mind the catastrophic ice flows or Glacier Girl buried under 260 feet of ice in just 50 years etc.

Rob Potter

So, in place of the d18O proxy (which has been widely used and accepted for a number of years), they propose two new proxies (one of which is related to snow thickness not temperature) neither of which have been used before. The rationale for this is that they fit an expectation that the temperature “should” have been warmer in one period of history, based on a model of solar irradiation and CO2 absorption.
Hmmmm, seems to me that this is another bit of finding evidence in support of a theory (instead of trying to falsify it). In fact, what it really illustrates is the legal methodology of casting doubt on inconvenient evidence that disproves your case. They might be correct, but I have my doubts.

Duster

The d-O18 proxy is known to be driven by thermal fractionation. The same effects should be visible in the relative amounts of other isotopes including C-13/C-12. That is, any warming that results in increased evaporation of water containing O18 should also result in increased prevalence of CO2 containing C-13, which should also appear in profiles of the gas trapped in ice. D-O18 and d-C13 should positively correlate.

Yes, thermal fractination, for which the condensation temperature of the cloud is the thermal imput. But the condensation temperature is also known as dewpoint and is totally dependent on the absolute moisture of the airmass at the origine and not on it’s temperature. Another factor is the Rayleigh rain out distillation. The longer the path the more depleted (cold) the precipitation gets. So you can change the absolute moisture of the source area and change the prevailing path of the airmasses to change isotope ratios at the destination on the ice sheets, without ever changing any temperature.

De Paus

This has nothing to do with science, but everything with money. Every time the CAGW scare needs an explanation because it evidently is wrong, there are more than enough funding grants for studies that “proove” that the CAGW scare is right after all. Global warming causes the melting of the North Pole ice. Oops, it is not melting. Well, the increase of the ice mass is caused by global warming aka climate change. David Viner, the greatest climate crook of all, said in 2000 that snow would be a thing of the past. Now they say the melting of polar ice (because of global warming) is causing extreme cold winters with lots of snow.
But the polar ice is growing and not melting. Very soon a new study will proove that global warming causes both growing polar ice and cold American and European winters. “Cooling is caused by warming”.
More or less the same way the growing Antarctic ice is explained because of rising South Pole temperatures. That Antarctic temperatures are plummeting is just a minor detail, nothing to bother the public with. Repeat a lie often enough and eventually it will be believed. The MSM are sure helping with that.

rgbatduke

I don’t think there is anything particularly controversial here. A method with comparatively poor resolution gave a puzzling answer. An arguably improved method gave a more reasonable answer. Neither answer is presented with a statement or portrayal of their expected/probable error, or the robustness of the finding — perhaps a core drilled a half mile away might have given a different answer for either method (this might be addressed in the paper, but in the figures and text above there is no hint of it if there is). So we are left not even knowing if these curves, decorated with their likely error, overlap to where they are indistinguishable or if they are probably distinct, separated by at least the error bar of the more accurate method. If the accuracy of either method can be estimated or computed in any sort of objective way.
The one thing that is amazing about the curves above either way is the sharpness of the BA/YD transition, and the YD/H transition at the end of the YD. If these curves accurately reproduce the data at all, this is simply amazing, almost unbelievable. Temperatures rose by roughly 15 C in a time span order of one century. That is 1.5C per decade. In ten years, the planet apparently warmed more than it has warmed in the last 300 years from the depths of the little ice age to the present! And then it did it again the next ten years, then the next, then the next.
This, my friends, is “unprecedented” warming. It is also damned difficult to understand or explain. In another thread, we have been discussing Milankovich and orbital dynamics as a “cause” of the pattern of ice age and interglacial/interstadial. It is simply inconceivable — to me, anyway — that any time evolution of orbital/precessional parameters, which proceed at a pace that would make a snail look like an olympic sprinter could suddenly cause any such shift on such a short time scale. And even this time scale is likely blurred and averaged by diffusion and the progression of time. It isn’t unreasonable that the actual change was even faster, with most of this warming occurring in two or three decades!
On the far side, the cooling is just as terrifying! More like 10 C over 150 to 200 years, so only 0.5 C/decade for twenty-odd decades in a row, but again, how could this possibly be? Neither of these transitions admits any sort of rational explanation within the capabilities of any of the climate models.
Finally, the third jump up to the Holocene is more of the same. Where is the dignified, slow progression one might expect of orbital dynamics slowly, slowly altering angles and the pattern and strength of insolation projected onto the continents? Totally absent! It’s a damn switch. The YD ended with a jump of 10-12 C in a single century, perhaps less, warming a full degree a decade (at least in the snowpack where this was measured).
The story is just as disheartening and scary in the second figure, even if the BA/YD jump is less pronounced. The curves look precisely the way one would expect if the system were transiently multistable with two distinct stability regimes and with a very low barrier in between them. It pops into warm phase all at once, and warms at a tremendous rate, but warm phase isn’t terribly stable either so it slowly decays until it pops equally suddenly back down to cold phase, plummeting back to full glacial conditions almost “overnight” on a cosmic scale, where it hangs out again for a while (as, we imagine, the world keeps precessing) until cold phase really does become unstable and it leaps straight back up to warm phase, this time to stay there.
This suggests that the system is enormously nonlinear, at least cubically nonlinear. It also suggests — to me — that the underlying structure of the warm and cold phase attractors is not at all trivial, with multiple ways for the system to probe right down to the stability boundary in its normal time evolution even in a locally stable phase, so that the system can behave in quite unexpected ways, quite suddenly. I have seen behavior just like this in studies of optical bistability and simulations of second order phase transitions — rapid oscillatory “switching” between the old, previously stable phase and a new emergent phase.
So the real point of the graphs above isn’t whether or not the YD was a bit warmer than the main part of the Wisconsin up to the BA. Who really cares? We can’t even come up with a convincing explanation for why the BA/YD transition occurred at all, at least not one that we can really back up with observational data. It is that we should all be very, very worried by the graphs themselves. They suggest that there is one thing that the warmists have right. The Earth’s climate system is perfectly capable of “catastrophic” behavior even without the slightest bit of human help. And I don’t mean by catastrophe that it can do things that are expensive or hurt people, I’m speaking of mathematical catastrophe theory:
http://en.wikipedia.org/wiki/Catastrophe_theory
Bifurcation theory that studies and classifies phenomena characterized by sudden and profound shifts in behavior arising from small changes in circumstances — a landslide triggered by a sneeze, a nuclear bomb ignited by the press of a small button, a fire that starts from a small spark. In most cases there is some sort of deep nonlinear instability that is held at bay by a barrier that comes apart, as it were, when touched quite gently in just the right way.
It is non-stationary behavior (as the climate is a non-stationary system) of the worst sort. This curve suggests that the planet really could plunge into the next ice age, laughing at the puny forcing of CO_2, at almost any moment if circumstances are just right and orbital precession and the evolution of the orbital ellipse itself has proceeded far enough to destabilize the warm phase, or that it could take it upon itself to “jump” straight up to temperatures not seen for fifty million years. Without human help.
More concretely, given that Greenland is warmed at least in part by persistent thermohaline circulation patterns, e.g. the Gulf Stream, it suggests that those patterns can suddenly alter for intervals lasting thousands of years (many complete turnovers of the thermohaline system!), putting Greenland and Europe literally into the deep freeze overnight. This sort of shift can probably be precipitated by comparatively tiny changes — a volcano that turns on underwater that lifts the sea bed and warms a patch of ocean that is supposed to be cold and dense, causing it to expand and block an existing circulation pattern into an easier route with no volcano. An earthquake that shifts an ocean bed, or knocks a chunk of coast down to partly block a channel, or breaks up a huge chunk of glacial ice that melts and screws up both salinity and temperature. A butterfly fish that flaps its fins in just the wrong way at just the wrong time. A volcanic explosion like Tambora, only larger. A medium sized asteroid.
And those patterns can just as suddenly shift back. Or shift to entirely new patterns that are even more warming, or cooling. The key thing is that a cooling shift can cause an enormous amount of very rapid cooling, a warming shift can cause an enormous amount of very rapid warming. 15 C is 27 F. That’s not “spring came a bit early this year” shifting, it is “honey, let’s put some banana trees into the back yard, now that winter isn’t happening any more”. Or the other way, it is time to pack and move to South Texas or the Sahara, the new temperate zone.
rgb

Latitude

” In most cases there is some sort of deep nonlinear instability that is held at bay by a barrier that comes apart, as it were, when touched quite gently in just the right way.”
You’re on a good roll today!……that was an excellent way of putting it

Sudden climate shifts characterize all glacial-interglacial transitions for at least the past 800,000 years. The really big moves like the BA and YD require massive ice melts leading to freshwater inputs into the North Atlantic. The long, hot MIS 11 interglacial for instance shows an abrupt cooling comparable the the 8.2 Ka event early in the Holocene:
http://www.sciencedirect.com/science/article/pii/S092181811200094X
The rapid changes also occur within glacials. The shifts are less steep and abrupt during interglacials. The reason appears to be higher temperatures to begin with and much less extensive NH ice sheets.
The latter Pleistocene seems to be tri-stable, with interglacial, glacial and glacial maximum or Heinrich Event (“super-glacial”) modes. Milankovitch cycles rule, but small changes in insolation can cause big swings when a lot of ice remains to melt into the Atlantic.

rgbatduke

I don’t know if you are still watching this thread, but can you direct me to examples of “super glacial” modes? Or is that what we are in now, as opposed to the more modest glaciation of the 41 ky cycle period?
rgb

I should have explained better.
Glacials have colder and less cold phases that are stable for up to thousands of years, as at the Last Glacial Maximum, which lasted at least from 22,000 to 19,000 calendar years before present. In this mode, the North Atlantic freezes over in winter, much as does the Arctic Ocean now, and even in summer, there is permanent ice around its western, northern and eastern arc.
The same pattern emerges during Heinrich Events, but doesn’t persist for as long.

RGB, I spent considerable time looking at the sudden transitions into and out of the YD. was going to write about it for the next book There is the fairly well discredited comet impact hypothesis,whose most recent attempted resurrection was via nano diamonds. There is a lot of support for the mechanism being sudden diversion of the Lake Aggassis meltwater from the Missippii river valley to the St. Laurence, most likely by melting of ice dams. The freshwater pulse (s) disrupted the north Atlantic thermohaline circulation, stopped northward surface heat transport, and caused YD. there is for example, seabed core evidence from the Florida straights suggesting this disruption. It is a bit shakier that the heat conveyor started up again almost as abruptly. The most recent paper posits that a major ice shelf formed around Greenland projecting into the Atlantic, broke off, and as it dissipated contributed to the fast restart of the full conveyer. There is some sea floor detritus deposition SE of Greenland to support the hypothesis, but not dateable to sufficient precision to be compelling. Is an area of active research.
What does seem certain is that neither comets, Lake Agassiz, nor a massive Greenland ice shelf are likely tipping points for CAGW. Well, maybe comets /sarc

Anything is possible

Rud Istvan September 4, 2014 at 2:57 pm
There is a lot of support for the mechanism being sudden diversion of the Lake Aggassis meltwater from the Missippii river valley to the St. Laurence, most likely by melting of ice dams.
==============================================
I remember studying this at University (a long time ago!). A.G. Dawson (Ice Age Earth) – no idea whether it is still in print – proposed that the dynamics of ice surging diverted large volumes of glacial meltwater into the Gulf of Mexico c.12,000 years ago. Could that have had the effect of shutting down the Gulfstream? That seems plausible to me, and If so, that would certainly help to explain the dramatic cooling observed in Greenland and NW Europe around that time.
According to Dawson, the diversion of glacial lake drainage into the St. Lawrence occurred later, when the ice retreated between 11,000 and 10,000 years BP. If that enabled the Gulfstream to start back up again, that would again be a plausible explanation for the dramatic warming which bought the YD to an end.

Duster

Rud, there are far too many anomalies at the YD to assume any one of them is the “cause.” The impact event, far from being discredited, is probably better established now than when Firestone first floated the idea. I’ve never liked it, but no longer argue against it. A nanodiamond anomally does seem to mark the YD and it has now been identified globally. At the same time, the YD also seems to be marked by a radiocarbon anomally with remarkably high concentrations of C-14. No impact event could have caused that. So, it seems unlikely that the two could be causally linked. It is conceivable that a high intensity airblast over the Laurentide Ice Sheet could cause or enhance a freshwater pulse adequate to suppress the NATHC. That could conserve both the North Atlantic conveyor hypothesis and the correlation with the nanodiamond layer.

This sort of shift can probably be precipitated by comparatively tiny changes — a volcano that turns on underwater that lifts the sea bed and warms a patch of ocean that is supposed to be cold and dense, causing it to expand and block an existing circulation pattern into an easier route with no volcano.
Hmm, tectonics. I would agree. Not warming, but submarine tephra. Nearby Icelandic atmospheric volcanoes are by far the most productive; they represent 2% of the world’s erupting volcanoes since 1600, but produced more then 30% of the world’s ejected thephra.
The illusive (good at playing hide and seek game) deep water cold current North Icelandic Jet current plus silting of Denmark Strait, which is only 600m deep, but about 200km of its breadth is covered with the sediment 500m deep!.
I’ve been going about it for 4-5 years (as Dr. S may or may not recall)

Anything is possible

Behold the power of the Gulfstream!

Greg Goodman

.

This curve suggests that the planet really could plunge into the next ice age, laughing at the puny forcing of CO_2, at almost any moment if circumstances are just right and orbital precession and the evolution of the orbital ellipse itself has proceeded far enough to destabilize the warm phase, or that it could take it upon itself to “jump” straight up to temperatures not seen for fifty million years. Without human help.

What these transitions suggest is a positive feeback is present in the system. It is ultimately bounded by negative feedbacks otherwise it would not stop changing.
There seems to be two stable states. I don’t see any indication that it can jump up again. AFAIK, there is no record that suggests a third stable state.
The next flip will almost certainly be downwards into a new glacial period.

phlogiston

The Atlantic Meridional Overturning Circulation AMOC of which the gulf stream is a part does indeed have a positive feedback. The gulf stream brings more saline as well as warmer water toward Europe from the Caribbean. Cooling in the near Arctic region then results in cold super saline water with density high enough to downwell to the ocean floor. This process is called the formation of “North Atlantic Deep Water” NADW. This downwelling drives the AMOC. Which increases Arctic salinity. Which drives the AMOC. Which increases Arctic salinity. Etc.
Oceanographic study of the YD compares sediment records of water temperatures at the Antarctic and Arctic, the SH and NH. What they find is smooth changes in the SH contrasting with sudden transitions between cold and warm in the NH. The cause of this is the nonlinear bistability of the AMOC (on-off) due to its positive feedback.
I agree that positive feedback in climate systems is bounded by negative feedbacks. Thus rapid changes always terminate.

“I don’t think there is anything particularly controversial here. ”
ya, the over reaction here is kind of stunning.

SunSword

Or it could be something else entirely. Perhaps the entire solar system moves through areas of increased cosmic dust, thus effectively “dimming” the solar input to the earth. Eventually the solar system transitions out of the region of cosmic dust, the effectively “increasing” the solar input to the earth.

Ashby Manson

The comments on this seem overly pessimistic. The paper claims to support a temperature curve that more closely tracks solar data and further de-correlates from CO2 levels. I find that intriguing. These sorts of results appear to further undermine the current models.

1sky1

Darn that 18O isotope! If one can find a foxy proxy that can be fully trusted, marry her tomorrow…in Las Vegas.

Robert of Ottawa

OFFS! The data is wrong, we must correct it. So can they explain the discrepancy with the N and O techniques?

Bill Illis

I’ll have to see the data, but I do NOT see any difference between the two temperature estimate methodologies. They are more-or-less identical estimates.
Neither the chart presented above nor in any of the ones presented in the paper or the supplemental.
http://www.sciencemag.org/content/345/6201/1177
Nothing has changed with this new paper (except someone got more bold in the spin than usual).

Wait a minute. N-15 is a stable isotope. Are they suggesting that there’s some kind of osmosis between N-15 and N-14 in the ice due to mass-exclusion? I find that to be a head-scratcher. Because both isotopes are stable, there shouldn’t be a difference between the two in abundance in the atmosphere, and the difference between the two, mass-wise, is so small that I find detection of such differences to be highly dubious. I’ll have to get the paper and read it to see what exactly they say.

ShrNfr

So, looking at their graph of temps, the temperature in Greenland has been falling for the past 5000 years, and the Medieval Warming Period and the Little Ice Age also existed there. How can this be true? Old “Hockey Stick” has been telling us otherwise. Further, the rise in the temperature should have destroyed all mankind prior to the decline in temperatures. Something is obviously wrong.
Btw, I have done the correlation between the year date and the date Mikey was born and the four year moving average of Hadcrut4 since 1908. They have a significant correlation of over .8. On this basis, I must conclude that Mikey is the cause of the temperature anomaly. I will have to double check this before publishing, of course, but at the moment, I see nothing the matter with the statistic.

prjindigo

All this awesome science yet we know that on any given year the top layer can melt away…
Technically ALL of the ice in Greenland is “hanging chad”

rgbatduke says which is at the heart of why/how the climate changes.
My explanation is first of all the state of the climate at that time was near boarder line threshold values of glacial versus non glacial conditions. This would then lend itself to given changes in items that exert influence on the climate to have a much greater influence. I think the ice dynamic plays a big part in all of this.
That said I think much smaller changes were needed in given items that control the climate to set a cascade of things in motion which could then shift the climate from one regime to another. Today it can still happen but the changes will probably have to be more substancial and last longer in duration.
My candidates are solar variability and associated primary and secondary effects, changes in the earth’s magnetic field which can either enhance or moderate solar variability , the initial state of the climate( which I just explained), and Milankovitch Cycles . However in regards to Milankovitch Cycles they were less favorable for glaciation then today’s parameters which include the tilt of the earth’s axis(less today then 12000 years ago ), eccentricity of the earth’s orbit(less today then 12000 years ago) and precession of the equinoxes(aphelion today now in N.H. summer) all favorable for cooling.
This leads me to conclude it is the initial state of the climate (the ice dynamic) moderated by solar variability (primary and secondary effects) further moderated by the weak earth magnetic field at that time. Gothenburg reversal or at least excursion taking place 11500 years ago. This then could bring the climate to threshold values both for rapid warming and rapid cooling.
It had nothing to do with co2 concentrations which are a by-product of the climate not a cause.
On the far side , the cooling is just as terrifying! More like 10 C over 150 to 200 years, so only 0.5 C/decade for twenty-odd decades in a row, but again, how could this possibly be? Neither of these transitions admits any sort of rational explanation within the capabilities of any of the climate models.

joelobryan

The best description BY FAR of what RGB wrote above, and what Salvatore Del Prete describes is in
“Catastrophe Theory for Scientists and Engineers”, by Robert Gilmore (copyright 1981). Chapter 16 Climate.
http://ecx.images-amazon.com/images/I/81y3iMbgonL.jpg
In Chap 16, he covers the Pacemaker of the Ice Ages, Milankovitch Theory, Test of the Milankovitch theory, Connection with Catastrophe Theory, Reduction to Cusp form, Toward a useful program, and an Epilogue. All very interesting if you can manage some of the complex math in the earlier chapters. His explanations of the Milankovitch cycles in 6 pages are outstanding without getting bogged down in the math of orbital mechanics.
The last 2 sentences of the Prologue to the 20 page chapter, Dr Gilmore wrote:
“The interglacial time in which we live began about 10 ky ago. Further, there is evidence to suggest that the transition between glacial and interglacial climate conditions may occur very rapidly, with a human lifetime or two (about 100 years), or possibly even faster.”
He wrote that in 1980, 10 years before the age of CAGW alarmism began with the first IPCC. Maybe Dr James Hansen should have read Dr Gilmore’s book a little closer.

So could the conclusion be right? I mean in terms of what the temps actually were. rgtb males a good point about the Way this points towards the instability of the ecosystem/ climate. There’s some cheap property in central America, no?

On the far side , the cooling is just as terrifying! More like 10 C over 150 to 200 years, so only 0.5 C/decade for twenty-odd decades in a row, but again, how could this possibly be? Neither of these transitions admits any sort of rational explanation within the capabilities of any of the climate models
That should have come at the beginning of my previous post not at the end. THANKS.

William McClenney

Nothing new here. Move along. Murphy told us yonks ago to draw our conclusions then gather our data. Of course, there are always those that didn’t get that memo.

Michael D

Hmm. i thought the science was settled?

Bill Illis

I downloaded the data and there is NO difference in the timelines between the two methodologies. The shifts in trends are different by maybe 10 years while the resolution of the data is 20 years ie. no difference.

Bill Illis
joelobryan

“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.”
Only true if you expect CO2, as a trace gas acting as a GHG, to be the dominant driver of global temperature. But when consideration of these last 18 years of the current Hiatus, with steadily climbing pCO2, it seems to be false.

John

Almost every major skeptic – Lindzen, Michaels, Curry, Mcintyre, McKittrick, Christy, Spencer, etc. – believes that CO2 warms the climate. The issue is how much.
Many people, maybe even some mainstream climate scientists, have noticed that there has been a big pause. The result has been a large number of new papers saying that the climate isn’t as sensitive to added CO2 as the models say. Looks to me, based on these new papers of the last several years, that a doubling of CO2 will increase temperatures by only about half of what the models say. Skeptics such as Judith Curry have said for years that there is substantial natural variability in the climate, that the models don’t include this variability, and the modellers don’t yet understand it.
There is much to criticize about the IPCC and mainstream modellers and all the PR people circling the wagons and exaggerating, all the Michael Manns of the climate science world.
But you won’t find many people, including most major skeptics, who think that a doubling of CO2 will have no influence on rising temperatures.

John

In the Alley et al (2000) graphic, temps in the Younger Dryas are a touch lower than at the end of the glacial period, just before the first big rise in temperatures (which occurred a little less than 15,000 years before present).
In the new study (first graph at top), temps in the Younger Dryas are a touch higher than at the end of the glacial period, just before the first big rise in temperatures.
Not much difference.
More importantly, I see nothing to be snarky about here. Trying to figure out temperatures in the period from 15,000 to about 10,000 years ago from snowpacks isn’t the kind of thing where you know exactly what to do in the year 2000, and the science “is (forever) settled.” This kind of complex science will change, and may change again.
The Bohr Institute isn’t the IPCC, they are much better, they are almost the opposite of Michael Mann in their integrity. You might also say the same about the lack of integrity of the Aussie Met bureau, based upon Jo Nova and recent articles in the Australian (newspaper).
Adjusting past temps to 15,000 years ago isn’t anything like the Aussies who recently adjusted many temperatures from perfectly accurate measurements in the last century simply because they apparently wanted to. Don’t condemn all climate science or scientists just because the IPCC and Michael Mann and the Aussie Met bureau are playing games and lack integrity.

Look at this chart by R.B. Alley:
http://postimg.org/image/kmyltwusz
If that doesn’t terrify you, nothing will. TENS of degrees temperature change, within only a decade or so. We would be lucky to avoid 1 billion+ deaths from starvation, exposure, and extreme weather events.
Looks like an On/Off switch, doesn’t it?
And the alarmist crowd is worried about a tiny 0.7ºC fluctuation over the past 150 years…

Greg Goodman

The SI gives a lot of detail and proper sized graphs.
http://www.sciencemag.org/content/suppl/2014/09/03/345.6201.1177.DC1/Buizert.SM.pdf
Suggest reading it before commenting.

Greg Goodman

It suggests the postitive feedback causing the flips is ice-albedo changes.

So they thought they needed to get rid of the Younger Dryas:

This was the exact opposite of what you would expect,” explains postdoc Vasileios Gkinis.

And then they say that they DID get rid of it. Okay.
So what about that explanation for the Younger Dryas that was published last week, the discovery of a nanodiamond layer distributed across at least a large expanse of the northern hemisphere (the area studied), indicating a large meteor or comet impact?
http://wattsupwiththat.com/2014/08/29/younger-dryas-climate-event-solved-via-nanodiamonds-it-was-a-planetary-impact-event/
If they knew they didn’t actually need to get rid of Younger Dryas cooling in order for those millennia to fit with their CO2-driven theory of climate, would they still have concluded that the cooling didn’t occur? Too bad we can’t run THAT experiment.

el gordo

Be careful what you wish for, but it does explain why CO2 remained relatively high during the Younger Dryas.

milodonharlani

The supposed impact-generated, hexagonal “nanodiamonds” aren’t, as has been repeatedly shown at their alleged sites.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2941276/
No evidence of nanodiamonds in Younger–Dryas sediments to support an impact event
Tyrone L. Daulton, Nicholas Pinter, and Andrew C. Scott
The Younger Dryas Impact Hypothesis is an evidence-free conjecture. All its various “impact” scenarios defy basic physics.

rgbatduke

The problem with the YD isn’t the lack of possible explanations, or the lack of at least some evidence to support those explanations. It is that none of the evidence (IMO) is in and of itself convincing, and none of the theories quite get over the hump of alternative corroborative support from multiple sources of evidence and possible confounding. A comet impact, for example, could have triggered freshwater melt or the alteration of an exit channel, freshwater melt might have created conditions that were unstable but a comet might have triggered the actual transition, etc. And the problem with human imagination is that the real cause could be something we haven’t thought of yet and both of these explanations could be wrong. Thermohaline circulation is just one of the things that easily could shift like a switch with some sort of millennium scale hysteresis; so is the massive release of “stuff” from a major comet impact (think “nuclear winter”). But there are more exotic (but still possible) explanations out there, I’m sure, and we may just never have looked at the particular pile of evidence that would cause somebody to have the light bulb go off in their head.
I like to believe in both the THC explanation AND the comet explanation. Just not completely in either one. Sort of like believing in Santa Clause AND the Easter Bunny as being the source of candy on my pillow as both are known for giving candy to small children, even though it could have been somebody I hadn’t really expected to dole out candy, like the tooth fairy. Evil little creature that she is, encouraging the loss of MORE teeth in small children with her sugary treats…
rgb

The craterless comet collision conjecture isn’t even good science fiction. All the various scenarios violate fundamental physics and are so statistically improbable as to rate as virtual impossibilities. Please see the 2012 AGU monograph on this topic:
http://scholar.google.com/scholar_url?hl=en&q=http://www.agu.org/books/gm/v198/2012gm001209/2012GM001209.pdf&sa=X&scisig=AAGBfm1E3ON3DCBD6A5qihKRHg8OCjAIrg&oi=scholarr
There is no need for a special explanation for the YD because it’s no different from any of the other of the hundreds of similar abrupt fluctuations in the record for the past million years at least. They are particularly sudden and steep around glacial-interglacial transitions.

Duster

They can’t “get rid” of the Younger Dryas. It is identified geologically, not by isotope ratios and has been known at least since 1938 when Jensen (1938) published pollen studies from the West Baltic. The geological evidence of glacial advances that mark it are not something you can get rid of and are observed globally. IIRC the YD was observed in the Alps and elsewhere over a century ago, well before Jensen, on the basis of moraines and other geological traces alone. The ice core data simply should show a record of “climate” that accompanied the ice advance. So, is is conceivable that one could mangle numbers until the anomaly vanishes from isotope profiles, but that will not hide rock piles left by glaciers.

The Younger Dryas is named after tough little Dryas octopetala (Mountain Avens), which flowers only in desolate tundra environments. Its durable pollen has long been used as a reliable indicator of arctic climate conditions many thousands of years ago, both for the Older Dryas from before the warm Allerod interval and the Younger Dryas after it in lake sediments.

What we discovered was that the previous temperature curve, which was only based on the measurements of the oxygen isotope O18, was inaccurate. “. Given that the previous temperature curve lies entirely within the error bounds of the new one, they quite simply can’t know whether the old or the new was right.
So the temperatures actually follow the solar radiation and the amount of carbon dioxide in the atmosphere.“. As rgbatduke has pointed out, there are some vastly more significant temperature differences that cannot possibly, not even in anyone’s wildest dreams, be caused by changes in solar radiation and CO2. So they simply don’t know what controlled the temperature.