Ice core data shows CO2 levels changed less than 10 parts per million from 1600-1800 during the MWP.
From the Hockey Schtick: A new paper from Schurer et al (with Mann as co-author) finds that climate “models cannot explain the warm conditions around 1000 [years before the present, during the Medieval Warming Period] seen in some [temperature] reconstructions.”
According to Schurer et al, “We find variations in solar output and explosive volcanism to be the main drivers of climate change from 1400-1900.” They also claim, “but for the first time we are also able to detect a significant contribution from greenhouse gas variations to the cold conditions during 1600-1800.” This claim is highly unlikely given that ice cores show CO2 levels only changed by less than 10 ppm from 1600-1800, and the effect of 10 ppm CO2 on the climate today remains undetectable even with modern instrumentation.
Separating forced from chaotic climate variability over the past millennium
Andrew Schurer,1 Gabriele Hegerl,1 Michael E. Mann,2 Simon F. B. Tett,1 and Steven J. Phipps3
Journal of Climate 2013 doi: http://dx.doi.org/10.1175/JCLI-D-12-00826.1
Abstract
Reconstructions of past climate show notable temperature variability over the past millennium, with relatively warm conditions during the ‘Medieval Climate Anomaly’ (MCA) and a relatively cold ‘Little Ice Age’ (LIA). We use multi-model simulations of the past millennium together with a wide range of reconstructions of Northern Hemispheric mean annual temperature to separate climate variability from 850 to 1950CE into components attributable to external forcing and internal climate variability. We find that external forcing contributed significantly to long-term temperature variations irrespective of the proxy reconstruction, particularly from 1400 onwards. Over the MCA alone, however, the effect of forcing is only detectable in about half of the reconstructions considered, and the response to forcing in the models cannot explain the warm conditions around 1000 [years before the present] seen in some reconstructions. We use the residual from the detection analysis to estimate internal variability independent from climate modelling and find that the recent observed 50-year and 100-year hemispheric temperature trends are substantially larger than any of the internally-generated trends even using the large residuals over the MCA. We find variations in solar output and explosive volcanism to be the main drivers of climate change from 1400-1900, but for the first time we are also able to detect a significant contribution from greenhouse gas variations to the cold conditions during 1600-1800. The proxy reconstructions tend to show a smaller forced response than is simulated by the models. We show that this discrepancy is likely to be, at least partly, associated with the difference in the response to large volcanic eruptions between reconstructions and model simulations.
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Heck, the climate models can’t even explain the present, let alone the past, so this really isn’t a surprise:
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“…for the first time we are also able to detect a significant contribution from greenhouse gas variations to the cold conditions during 1600-1800.” ~ Mann, et al.
Given the time frame and claimed resolution why doesn’t the model explain correctly the last 15 years?
The computer models do not work, what part of that statement do climate scientists not understand?
As this is ‘climate science’, is The Great Fire of London in 1666 of any relevance?
It must have produced a lot of CO2, perhaps that might help Mann find his missing evil gas. It is just as good a reason as the other stuff he makes up.
Cause or effect? Is there a relationship between decreases in atmospheric CO2 and/or temperature during the Little Ice Age and population declines at high altitudes (the Altiplano)
at that time?
Looks like the glue that they used to stick their models together with is coming undone…
I haven’t been able to find the paper I read it in, but I read years ago that modelers had to jack up sensitivity to Co2 to get the models to increase temps as measured, and while there’s nothing wrong with doing something like that to guide research for a physical mechanism, it’s not proof.
But, the point is I don’t think Mann is a modeler, I think the wheels are starting to wobble, and Mann just threw the modeler (Hansen) under the bus.
“Ice core data shows CO2 levels changed less than 10 parts per million from 1600-1800 during the MWP.”
I think you meant LIA.
Earth to Leif Svalgaard, comments?
“We find variations in solar output and explosive volcanism to be the main drivers of climate change from 1400-1900”
Every time I go to the store and pay for something I whip out a twenty dollar bill (or multiples thereof) and look at the person at the cash register with the most honest, sincere, and bland expression I can think of. As I hand the cashier the bill, making certain the expression I described is riveted to my face, I say, “This is not really a twenty dollar bill.” With genuine sincerity I then say, “It’s really a two hundred dollar bill.” And then with the tone of my voice just oozing honesty I immediately employ the ‘trick’, “It’s just that you can’t see the other zero, but trust me, it’s there.” I really do this. I’m not making this up. And the reason you can believe me when I say that I really do this is when I tell you that it never works. Ever. And, in fact, the cashiers tend to laugh at me. (Which is a little better outcome than being arrested.)
It would be nice if the powers that be had the same sense of humor and practicality that these cashiers had for, if that was the case, Michael Mann would have had a career as an old fart trying to pan off twenty dollar bills which contain magic signals turning them into two hundred dollar bills, rather then the damaging career he has now.
dp says:
April 11, 2013 at 10:40 am
He is quick to avoid leaving anything stupid unsaid. Models only report back what we tell them and in a way we have told them. If climate models were self-modifying AI they would surely pull the pin before dishing out the trash they are told to create.
——————————-
I worked on inertial navigators during the 70’s. Great system but we had to update it every few days or so using GPS, sonar, LORAN, and a Type XI Periscope we used to get a star fix.
We said it was a “multi-million dollar system that will tell you where you are as long as you tell it where it is.”
Sounds a lot like Dr. Mann’s proxies. They’ll tell you what the temperature was if you know what you want the temperature to have been.
So is Mann admitting previous research (no MWP) was a waste or lie or what?
cn
Alan S. Blue says:
April 11, 2013 at 11:11 am
It would be interesting to have an ongoing chart of the -residuals- of all of the competing models. Or, at least, the running least-squared error between models and observations. Both as independent models and as the “ensemble”. This is a pretty stock method of comparing models with reality, I know of no legitimate reason to avoid this for climate science.
*******
This was actually done (at least in part) in my paper
Scafetta N., 2012. Testing an astronomically based decadal-scale empirical harmonic climate model versus the IPCC (2007) general circulation climate models. Journal of Atmospheric and Solar-Terrestrial Physics 80, 124-137.
http://www.sciencedirect.com/science/article/pii/S1364682611003385
see Figure 6.
http://people.duke.edu/~ns2002/pdf/ATP3533.pdf
****************************
by the way,
for those who might be interested, I just published a new paper
Scafetta, N., O. Humlum, J.-E. Solheim, and K. Stordahl, 2013. Comment on “The influence of planetary attractions on the solar tachocline” by Callebaut, de Jager and Duhau. Journal of Atmospheric and Solar–Terrestrial Physics. DOI: 10.1016/j.jastp.2013.03.007
http://authors.elsevier.com/sd/article/S1364682613000837
http://people.duke.edu/~ns2002/pdf/ATP_3797.pdf
which rebuts a paper discussed on this website last year.
http://wattsupwiththat.com/2012/04/15/new-paper-in-the-journal-of-atmospheric-and-solar-terrestrial-physics-demonstrates-that-planets-do-not-cause-solar-cycles/
Just remember – these people are getting paid to write this stuff…and WE are footing the bill. I’m afraid the joke’s on us…
“MiCro says:
April 11, 2013 at 11:58 am
I haven’t been able to find the paper I read it in, but I read years ago that modelers had to jack up sensitivity to Co2 to get the models to increase temps as measured, and while there’s nothing wrong with doing something like that to guide research for a physical mechanism, it’s not proof.”
It is perfectly legitimate to modify all and any variables in any computer model to see what the projected output is. What is NOT legitimate is to then state that that model is reality. I am still astonished that the whole AGW scam is based on giving precedence to the output of models over real world data – even more so, that people don;t get that this is not science but dogma.
FYI, co-author Steven Phipps is a modeler from Australia who is also a co-author on the Gergis fiasco (when will that paper see the light of day):
http://web.science.unsw.edu.au/~sjphipps/publications.html
‘Medieval Climate Anomaly’
I like it. Having refused to admit it’s existence for the last 15 years or so, they have to rename it something else. Note MWP still did not exist, but there was MCA at about the same time. LOL
Then we note a nuance of the new spin , note the word “anomaly”, ie that which is abnormal. It can’t be “normal” because it was not produced by CO2. It is not a natural ‘warm period”, it is anomalous.
Of course the models,being “tuned” to best match the last half of the 20th c record do not even hind-cast the first half. What hope of reproducing anything that far outside the calibration period?
And to think these jokers are marking up career brownie points by publishing this drivel.
Yet more evidence of the widespread corruption of science and abandonment of the scientific method.
Why have they started calling it the Medieval Climate Anomaly? It lasted for over two centuries. Is it the same PR trick as changing AGW to Climate Change?
How can they now be sure that that is not the normal state of climate, a state that existed for over four thousand years following the demise of the ice age, and repeated for half a century through the time of the Romans?
Oh that this pin head were larger,
Danceaway, Danceaway, Danceaway all,
On prancer Mann, On fancy Gore,
Danceaway danceaway, all
Smaller feet, smaller reduced to
Danceing small, all,, feet intangled
Smile, Dance, show all, you can still
Dance the hockey stick dance for all,
Gold, fools gold, mine for all time,
This CO2 fraud miss-minted rusty coin.
Oh, that this pin head would just stop
srinking, shrinking no room for all.
Tez says:
April 11, 2013 at 12:45 pm
Why have they started calling it the Medieval Climate Anomaly? It lasted for over two centuries. Is it the same PR trick as changing AGW to Climate Change?
=======================================================
Why? Because they are fanatical ideologues. Ergo – extremely dangerous.
If you check out Nicola’s site, certainly use compatability mow for IE.
@Chuck
“We said it was a “multi-million dollar system that will tell you where you are as long as you tell it where it is.”
LOL!
Can’t model it so erase it from history, Mike Mann for OMB budget director.
Alternative abstract
Reconstructions of past climate show notable temperature variability over the past millennium, with relatively warm conditions during the ‘Medieval Climate Anomaly’ (MCA) and a relatively cold ‘Little Ice Age’ (LIA). We have tweaked multi-model simulations of the past millennium together with a wide range of reconstructions of Northern Hemispheric mean annual temperature to separate model inconsistency from 850 to 1950CE into components attributable to external forcing and internal model variability. We find that external model tweaking contributed significantly to long-term temperature variations irrespective of the proxy reconstruction, particularly from 1400 onwards. Over the MCA alone, however, the effect of model tweaking is only detectable in about half of the reconstructions considered, and the response to forcing in the models cannot explain the warm conditions around 1000 [years before the present] seen in real data. We use the residual from the detection analysis of abberant models to estimate internal variability independent from climate and find that the recent observed 50-year and 100-year hemispheric model trends are substantially larger than any of the measured temperature trends even using the large residuals over the MCA. We find variations in solar output and explosive volcanism to be the main drivers of climate change from 1400-1900, but for the first time we are also able to detect a complete lack of any contribution from greenhouse gas variations to the cold conditions during 1600-1800. The proxy reconstructions tend to show a smaller forced response than is simulated by the models. We show that this discrepancy is likely to be, at least partly, associated with the difference in the response to large volcanic eruptions between the complete lack of response of reconstructions and model simulations.
Can the climate models explain Michael Mann? if not, can we really be sure he exists? Is it possible he’s just an epiphenomenon?
Wake me up, when models will explain this one:
http://woodfortrees.org/plot/hadcrut3vgl/from:1910/to:1945
Models (CMIP3/5) predict mere 0,1C increase for that period, while in reality it was 7-8 times more.
So “We find variations in solar output and explosive volcanism to be the main drivers of climate change from 1400-1900, but for the first time we are also able to detect a significant contribution from greenhouse gas variations to the cold conditions during 1600-1800.”…
Thus the cold winters come from global warming. Next, glaciations are great whiffs of warming too… QED.