Sun said to be “bi-modal”
While many, including the IPCC, suggest the modern Grand Maximum of solar activity from 1950-2009 has nothing to do with the 0.4C global warming measured over that time frame, it does seem to be unique in the last three millennia.
from CO2 Science: A 3,000-Year Record of Solar Activity
What was done
According to Usoskin et al. (2014), the Sun “shows strong variability in its magnetic activity, from Grand minima to Grand maxima, but the nature of the variability is not fully understood, mostly because of the insufficient length of the directly observed solar activity records and of uncertainties related to long-term reconstructions.” Now, however, in an attempt to overcome such uncertainties, in a Letter to the Editor published in the journal Astronomy and Astrophysics, Usoskin et al. “present the first fully adjustment-free physical reconstruction of solar activity” covering the past 3,000 years, which record allowed them “to study different modes of solar activity at an unprecedented level of detail.”
What was learned
As illustrated in the figure below, the authors report there is “remarkable agreement” among the overlapping years of their reconstruction (solid black line) and the number of sunspots recorded from direct observations since 1610 (red line). Their reconstruction of solar activity also displays several “distinct features,” including several “well-defined Grand minima of solar activity, ca. 770 BC, 350 BC, 680 AD, 1050 AD, 1310 AD, 1470 AD, and 1680 AD,” as well as “the modern Grand maximum (which occurred during solar cycles 19-23, i.e., 1950-2009),” which they describe as “a rare or even unique event, in both magnitude and duration, in the past three millennia.”
Further statistical analysis of their reconstruction revealed the Sun operates in three distinct modes of activity – (1) a regular mode that “corresponds to moderate activity that varies in a relatively narrow band between sunspot numbers 20 and 67,” (2) a Grand minimum mode of reduced solar activity that “cannot be explained by random fluctuations of the regular mode” and which “is confirmed at a high confidence level,” and (3), a possible Grand maximum mode, but they say that “the low statistic does not allow us to firmly conclude on this, yet.”
What it means
Usoskin et al. (2014) write their results “provide important constraints for both dynamo models of Sun-like stars and investigations of possible solar influence on Earth’s climate.” They also illustrate the importance of improving the quality of such reconstructions, in light of the fact that previous reconstructions of this nature “did not reveal any clear signature of distinct modes” in solar activity.
Unfortunately, it was beyond the scope of this paper to address the potential impact of solar activity on climate. Yet the reconstruction leaves a very big question unanswered — What effect did the Grand maximum of solar activity that occurred between 1950 and 2009 have on Earth’s climate? As a “unique” and “rare” event in terms of both magnitude and duration, one would think a lot more time and effort would be spent by the IPCC and others in answering that question. Instead, IPCC scientists have conducted relatively few studies of the Sun’s influence on modern warming, assuming that the temperature influence of this rare and unique Grand maximum of solar activity, which has occurred only once in the past 3,000 years, is far inferior to the radiative power provided by the rising CO2 concentration of the Earth’s atmosphere.
Reference
Usoskin, I.G., Hulot, G., Gallet, Y., Roth, R., Licht, A., Joos, F., Kovaltsov, G.A., Thebault, E. and Khokhlov, A. 2014. Evidence for distinct modes of solar activity. Astronomy and Astrophysics 562: L10, doi: 10.1051/0004-6361/201423391.
Abstract
Aims. The Sun shows strong variability in its magnetic activity, from Grand minima to Grand maxima, but the nature of the variability is not fully understood, mostly because of the insufficient length of the directly observed solar activity records and of uncertainties related to long-term reconstructions. Here we present a new adjustment-free reconstruction of solar activity over three millennia and study its different modes.
Methods. We present a new adjustment-free, physical reconstruction of solar activity over the past three millennia, using the latest verified carbon cycle, 14C production, and archeomagnetic field models. This great improvement allowed us to study different modes of solar activity at an unprecedented level of details.
Results. The distribution of solar activity is clearly bi-modal, implying the existence of distinct modes of activity. The main regular activity mode corresponds to moderate activity that varies in a relatively narrow band between sunspot numbers 20 and 67. The existence of a separate Grand minimum mode with reduced solar activity, which cannot be explained by random fluctuations of the regular mode, is confirmed at a high confidence level. The possible existence of a separate Grand maximum mode is also suggested, but the statistics is too low to reach a confident conclusion.
Conclusions. The Sun is shown to operate in distinct modes – a main general mode, a Grand minimum mode corresponding to an inactive Sun, and a possible Grand maximum mode corresponding to an unusually active Sun. These results provide important constraints for both dynamo models of Sun-like stars and investigations of possible solar influence on Earth’s climate.
Correct me if I am wrong, but I am under the impression that you believe the LIA is be externally solar forced. Thus you also subscribe to a “special explanation”. No?
Pamela Gray says:
August 10, 2014 at 12:53 pm
First, begging the question is the name of a logical fallacy. It does not mean the same as “raising the question”. That misuse is a pet peeve of mine.
You still don’t get that a volcanic effect has never been observed on climate. Whatever effect even the biggest eruptions have on Walker Cells or ENSO is short-lived, as I’ve repeatedly showed you and as your own expert Robock admits. It’s weather, not climate. No volcanic eruption has the ability to alter fundamental, underlying ENSO patterns. It has not been shown for any eruption or series of eruptions. Your hopeful hand waving can’t change that fact.
Look at the link I just pasted. Somehow ENSO anticipated the 1257 eruption, then did not react to it after it occurred. The pattern is exactly the opposite of your conjecture. The last blue phase ended around 1250, then the pattern returned to the red after red phase of the MWP until about 1350, which change again rapidly returned to the MWP norm until well into the LIA, c. 1500 (although late 15th century data are missing).
Before you can imagine a volcanic effect upon climatic scale temperature and oceanic circulation, you have to show that there was one, for which there is no evidence. Indeed, all the evidence is against your WAG.
Pamela Gray says:
August 10, 2014 at 12:55 pm
Absolutely not, as should have been obvious had you read what I’ve written.
No special explanation is needed since the LIA is no different from any of the tens of thousands of similar climatic fluctuations over at least the past 20 million years. During glacials, they’re called D/O Cycles and during the Holocene and other interglacials, Bond Cycles.
IMO they are driven by the same orbital and rotational mechanics as the glacial and interglacial cycles themselves, but that’s not a special explanation for one of them, but a general explanation, with abundant support, for all of them.
But it doesn’t matter what I think causes them. The fact is you have not shown the Null Hypothesis false, so there is no need to presume the special cause of volcanism for the LIA, unless you’re prepared to argue that all similar observed fluctuations have been caused by volcanoes, which proposition is easily shown false.
Surely this distinction can’t escape you.
Dr Norman I wish you 120 years with so a clear mind.
salvatore del prete says:
August 10, 2014 at 12:21 pm
The solar lull 2008-2010 goes a long way in confirming solar variability is greater then what is presently thought.
You are not paying attention. Lockwood and Co. show that solar variation is smaller than previously thought, in addition to grudgingly admitting that my reconstruction of ten years ago is correct. Their modelling of the Maunder Minimum is incorrect and a moving target. They disagree with themselves in more recent papers. By frantically parroting yourself over and over again you just sound like a broken record.
Milankovitch cycles have probably always operated, although some of their parameters probably have changed a lot since the moon was close.
This paper shows them operating during the Lower Cretaceous:
http://www.searchanddiscovery.com/pdfz/documents/2009/40388hinnov/ndx_hinnov.pdf.html
Again, the point is that there is no reason to suppose that the MWP and LIA were caused by any forces other than those which produced similar fluctuations for at least tens of millions of years, and probably billions.
So Sturgis, solar variability does not play into your thesis?
salvatore del prete says:
August 10, 2014 at 12:04 pm
The data any way it is sliced shows solar activity changed quite a bit during year 2005 into a much quitter state.
It does that every 100 years or so, nothing new there. http://www.leif.org/research/Ap-1844-now.png
And I am specifically referring to the past 1000 years.
Pamela Gray says:
August 10, 2014 at 1:25 pm
My thesis with respect to your baseless conjecture is that there is no reason to assume a volcanic cause for the LIA, and all the evidence in the world against it.
I’ve already repeatedly written what I think causes centennial to millennial scale climatic fluctuations. Solar variability obviously plays a role, but orbital mechanical modulation of whatever the sun sends out way is IMO more important on every time scale from decades to at least hundreds of thousands of years.
This hypothesis is not only well supported physically and by observation, but explains why there is no reason to suppose a volcano in 1257 caused the Little Ice Age, which all data sets show commencing sometime from c. 1350 to 1450. I’ve pasted here the CET data. Pick your own start date, but how you can get an AD 1250 start, when one of the two warmest 50 years of the MWP began, out of those or any other data is beyond me.
In any case, there is no reason to imagine the volcano caused the LIA, which is no different from tens of thousands of other such cycles in the Pleistocene and Holocene. Besides which, there is no evidence to support the climatic effect you imagine. Indeed all available evidence is against the conjecture.
Leif! You are not the only person who is right in any solar related cases. There is refrees whom are professionals too.
Here is one I have often referred to in my comments in several threads related to the Little Ice Age and weather pattern regime shifts. While the exact mechanism of prolonged affects following such volcanic explosions are up for debate, the fact some kind of sustaining intrinsic mechanism tied to disrupted oceanic/atmospheric processes is currently of high interest to such researchers.
“Our precisely dated records demonstrate that the expansion of ice caps after Medieval times was initiated by an abrupt and persistent snowline depression late in the 13th Century, and amplified in the mid 15th Century, coincident with episodes of repeated explosive volcanism centuries before the widely cited Maunder sunspot minimum (1645– 1715 AD [Eddy, 1976]).”
http://onlinelibrary.wiley.com/doi/10.1029/2011GL050168/abstract;jsessionid=F6F74F9AAF52F983F07A6F7AAC52B6A7.f01t01
Pamela Gray says:
August 10, 2014 at 1:26 pm
The past 1000 years are no different from the past 2.8 million years, at the very least. The same cycles are visible throughout the Pleistocene and Holocene, again at the very least. The Medieval Warm Period was warmer than now, but cooler than the Roman and Minoan Warm Periods and the Holocene Optimum. The LIA was cooler in some data sets than the Dark Ages Cold Period (which fell between the Roman and Medieval WPs), but not in others. It may have been cooler than the Greek Dark Ages Cold Period (which fell between the Minoan and Roman WPs).
I’ve pasted links to the Miocene and Lower Cretaceous (100 to 146 Ma) showing the same Milankovitch pattern.
A 1250 start date? No. I have cited link after link the proposes a 1257-58 start date immediately following the 1257 explosion.
You say orbital and axial wobble changes have a decadal affect????? Good heavens. Now you are the one clearly out on a limb. Do you know the watts/m2 change on a decadal scale related to these wobbles? And do you have any peer reviewed links that demonstrate this minute watts/m2 change can affect weather pattern variations and regime shifts? I have never come across such research but would be clearly interested in the link if you have it. The main cycle I get. But decadal? That’s nonsense.
Pamela Gray says:
August 10, 2014 at 1:37 pm
Do you know who Gerald “Dead Moss Clumps” Miller is? Search this blog for commentary on his unmitigated garbage.
If you like dead moss clumps, you’ll love climate models, as apparently you do.
Real data sets, not models, show at most a transient weather effect from the 1257 eruption. Maybe if you read Miller’s whole paper, you’d get an inkling at how egregiously bad it is. But even he is forced to admit that the real LIA didn’t begin until the 15th century.
Nor has he or anyone else, including you, shown any possible mechanism by which the 1257 and 1280 eruptions could have caused the LIA. It’s all hand waving. Nor has anyone shown actual data in which such a climate shift occurred as a result of temporary weather changes.
It didn’t happen after the 19th and 20th century eruptions during which good thermometer data are available, and there is no signal for any of the historical or prehistorical eruptions in climate proxy data.
The whole corrupt enterprise aims to “get rid of the MWP”, and you have bought into it.
Sad.
Pamela Gray says:
August 10, 2014 at 1:44 pm
Multidecadal is clearly indicated, namely the PDO and AMO. As I’ve repeatedly said, climate needs at least three decades, so I supposed you understood what I meant by decadal. But the LIA and MWP are centennial to millennial phenomena. That’s what we’re talking about.
I’m on no limb, but yours broke as soon as you went out on it.
Sturgis, you would be hard pressed to get decadal affects out of the Milankovitch data.
http://www.climatedata.info/Forcing/Forcing/milankovitchcycles.html
Sturgis
I have posted numerous times here the contemporary observations from the 13th century. These have been gleaned from a variety of sources including the Met office library and archives This includes our translation of 13th century manorial records from Latin and French into English.
I have also examined church records as these record alms given to the poor during extreme weather conditions.
The weather had already turned down some 5 or 6 years before the 1257 eruption. It recovered to previous warm levels within a couple of seasons of the eruption. After several further ups and downs the climate turned very warm during the first half of the 14 th century. Giss miller and his moss reconstructions are even more flawed than mann’s tree ring efforts. He tried to explain away why he couldn’t pick up the 1257 eruption. The reason being it had little effect on climate other than a season or two.
I can find little evidence of any lasting effect of volcanic eruptions on climate during the LIA other than transitory ones
Tonyb
Tonyb says:
August 10, 2014 at 1:56 pm
Nor can I.
The ENSO pattern data from Pacific corals also show a brief cold interval before the eruption, but return to warming thereafter. Amazing how climate can anticipate eruptions. Maybe there is a physical explanation for this apparently accidental phenomenon.
Then I find you vague. Are you saying that the LIA and MWP are forced by a piece of the Milankovitch mechanism that changes the Earth-Sun geometry? That makes no sense.
Pamela Gray says:
August 10, 2014 at 1:55 pm
Did you really miss my many references to climate being the 30 year average, at least, of climate?
Had I known you were such an inattentive reader, I’d have typed multidecadal instead of decadal, although since orbital and rotational mechanics are continuous, there’s no theoretical reason why there might not be hard to detect decadal or even annual effects on insolation, probably swamped by other parameters.
Sturgis, no. Climate is a quasi-stable state due to geography and oceanic/atmospheric broad scale teleconnections. Weather pattern variations and regime shifts can be longer than 30 years. Easily so. But climate is a rather stable entity due to its geophysical confines.
My view of climate admittedly diverges from the current fad among researchers to refer to weather as “climate”. I believe that is driven by sensationalism. It is scarier to say the climate is changing. Not so scary to say that we are in a weather pattern regime shift.
Pamela Gray says:
August 10, 2014 at 1:59 pm
My opinion doesn’t matter. We’re discussing your baseless assertion that a volcanic eruption caused the LIA during the MWP.
But yes, I do find it sensible that the continuously operating Milankovitch cycles do have climatic effects on centennial and millennial scale fluctuations like the MWP and LIA and their thousands of predecessors in the Pleistocene and Holocene. It’s hard to imagine how that could not happen, when longer term, orbital mechanics are strongly associated with rate of change in ice volume on our planet. IMO it’s reasonable to assume shorter term orbital and rotational changes could cause less dramatic, shorter-lived climatic fluctuations than the big ones like glaciations and interglacials.
Not only sensible and reasonable, but a defensible hypothesis amply supported by observations, unlike your conjecture, which is entirely without valid support.
Please see Tony’s comment on Miller’s alleged proxy data.