Solar activity measured by isotope proxies revealed the end of 20th century was the highest activity in 1200 years
A 2010 paper (that I somehow missed) was recently highlighted by the blog The Hockey Schtick and I thought it worth mentioning here even if a bit past the publish date.
The work by Ilya G. Usoskin of the Sodankyla Geophysical Observatory at the University of Oulu, Finland was published in Living Reviews of Solar Physics. The paper examines records from two isotope proxies (Be10 and C14) and finds that solar activity at the end of the 20th century was at the highest levels of the past 1200 years. Excerpts follow along with a link to the full paper.
A History of Solar Activity over Millennia
Ilya G. Usoskin, Sodankyla Geophysical Observatory (Oulu unit), University of Oulu, Finland
Abstract:
Presented here is a review of present knowledge of the long-term behavior of solar activity on a multi-millennial timescale, as reconstructed using the indirect proxy method. The concept of solar activity is discussed along with an overview of the special indices used to quantify different aspects of variable solar activity, with special emphasis upon sunspot number.
Over long timescales, quantitative information about past solar activity can only be obtained using a method based upon indirect proxy, such as the cosmogenic isotopes 14C and 10Be in natural stratified archives (e.g., tree rings or ice cores). We give an historical overview of the development of the proxy-based method for past solar-activity reconstruction over millennia, as well as a description of the modern state. Special attention is paid to the verification and cross-calibration of reconstructions. It is argued that this method of cosmogenic isotopes makes a solid basis for studies of solar variability in the past on a long timescale (centuries to
millennia) during the Holocene.
A separate section is devoted to reconstructions of strong solar–energetic-particle (SEP) events in the past, that suggest that the present-day average SEP flux is broadly consistent with estimates on longer timescales, and that the occurrence of extra-strong events is unlikely. Finally, the main features of the long-term evolution of solar magnetic activity, including the statistics of grand minima and maxima occurrence, are summarized and their possible implications, especially for solar/stellar dynamo theory, are discussed.
…
4.4 Grand maxima of solar activity
4.4.1 The modern episode of active sun
We have been presently living in a period of very high sun activity with a level of activity that is unprecedentedly high for the last few centuries covered by direct solar observation. The sunspot number was growing rapidly between 1900 and 1940, with more than a doubling average group sunspot number, and has remained at that high level until recently (see Figure 1). Note that growth comes entirely from raising the cycle maximum amplitude, while sunspot activity always returns to a very low level around solar cycle minima. While the average group sunspot number for the period 1750 – 1900 was 35 ± 9 (39 ± 6, if the Dalton minimum in 1797 – 1828 is not counted), it stands high at the level of 75 ± 3 since 1950. Therefore the modern active sun episode, which started in the 1940s, can be regarded as the modern grand maximum of solar activity, as opposed to a grand minimum (Wilson, 1988b).
Is such high solar activity typical or is it something extraordinary? While it is broadly agreed that the present active sun episode is a special phenomenon, the question of how (a)typical such upward bumps are from “normal” activity is a topic of hot debate.
…
6 Conclusions
In this review the present knowledge of long-term solar activity on a multi-millennial timescale, as reconstructed using the indirect proxy method, is discussed.
Although the concept of solar activity is intuitively understandable as a deviation from the “quiet” sun concept, there is no clear definition for it, and different indices have been proposed to quantify different aspects of variable solar activity. One of the most common and practical indices is sunspot number, which forms the longest available series of direct scientific observations. While all other indices have a high correlation with sunspot numbers, dominated by the 11-year cycle, the relationship between them at other timescales (short and long-term trends) may vary to a great extent.
On longer timescales, quantitative information of past solar activity can only be obtained using the method based upon indirect proxy, i.e., quantitative parameters, which can be measured nowadays but represent the signatures, stored in natural archives, of the different effects of solar magnetic activity in the past. Such traceable signatures can be related to nuclear or chemical effects caused by cosmic rays in the Earth’s atmosphere, lunar rocks or meteorites. The most common proxy of solar activity is formed by data from the cosmogenic radionuclides, 10Be and 14C, produced by cosmic rays in the Earth’s atmosphere and stored in independently-dated stratified natural archives, such as tree rings or ice cores. Using a recently-developed physics-based model it is now possible to reconstruct the temporal behavior of solar activity in the past, over many millennia. The most robust results can be obtained for the Holocene epoch, which started more than 11,000 years ago, whose stable climate minimizes possible uncertainties in the reconstruction.
An indirect verification of long-term solar-activity reconstructions supports their veracity and confirms that variations of cosmogenic nuclides on the long-term scale (centuries to millennia) during the Holocene make a solid basis for studies of solar variability in the past. However, such reconstructions may still contain systematic uncertainties related to unknown changes in the geomagnetic field or climate of the past, especially in the early part of the Holocene.
Measurements of nitrates in polar ice allow the reconstruction of strong solar energetic particle (SEP) events in the past, over the five past centuries. Together with independent measurements of the concentration of different cosmogenic isotopes in lunar and meteoritic rocks, it leads to estimates of the SEP flux on different timescales. Directly space-borne-measured SEP flux for recent decades is broadly consistent with estimates on longer timescales – up to millions of years, and the occurrence of extra-strong events is unlikely.
In general, the following main features are observed in the long-term evolution of solar magnetic activity.
• Solar activity is dominated by the 11-year Schwabe cycle on an interannual timescale. Some additional longer characteristic times can be found, including the Gleissberg secular cycle, de Vries/Suess cycle, and a quasi-cycle of 2000 – 2400 years. However, all these longer cycles are intermittent and cannot be regarded as strict phase-locked periodicities.
• One of the main features of long-term solar activity is that it contains an essential chaotic/stochastic component, which leads to irregular variations and makes solar-activity predictions impossible for a scale exceeding one solar cycle.
• The sun spends about 70% of its time at moderate magnetic activity levels, about 15 – 20% of its time in a grand minimum and about 10 – 15% in a grand maximum. Modern solar activity corresponds to a grand maximum.
• Grand minima are a typical but rare phenomena in solar behavior. Their occurrence appears not periodically, but rather as the result of a chaotic process within clusters separated by 2000 – 2500 years. Grand minima tend to be of two distinct types: short (Maunder-like) and longer (Sp¨orer-like).
• The modern level of solar activity (after the 1940s) is very high, corresponding to a grand maximum. Grand maxima are also rare and irregularly occurring events, though the exact rate of their occurrence is still a subject of debates. These observational features of the long-term behavior of solar activity have important implications, especially for the development of theoretical solar-dynamo models and for solar-terrestrial studies.
Full paper here: A History of Solar Activity over Millennia (PDF)
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However, according to the IPCC, none of this has nothing to do with 0.7C of global warming since the end of the Little Ice Age in 1850. And, even if you were to point it out to them for AR5, they have now clearly demonstrated they have no intention of paying any attention to any factual data that doesn’t fit the ‘CO2 and nothing else’ meme.
Maxima is plural; minimum is singular:
Paper demonstrates solar activity was at a grand maximum in the late 20th century
So who was counting sunspots, 9,000 years ago ? And what happened to the all time historicrecod sunspot peak during the IGY in 1957/8, that was pushing up toward 200 ?
Just asking.
REPLY: Be10 and C14 records, not sunspots. See the captions.
Why should The Team or The Match Committee bother to pay any attention to such information. We are now in the grand minimum certainty period of “post normal science” according to a cluster of geniuses and there is no place for anything but uncertainty because without uncertainty there could be no post normal science. Don’t you get that? (/sarc)
Not that I don’t agree or disagree with the paper but SSN is very subjective and using proxies is also subjective since the solar community can not agree on what is or is not a good proxy for solar activity. Also the graph looks a little too similar to the “Al Gore ” graph in that spoof film. Proxies also fall apart after the post atom bomb testing. If L an dP are correct then the SSN is not a good proxy but flux is a better way for looking at past solar activity. Seems a bit to convenient.
looks like a hockey schtick….funny that.
Looks like a hockey schtick…. Funny that.
I am not sure what can really be deduced from this – the medieval warm period doesn’t look particularly active.
No doubt Leif will tell us it is all wrong and link to his papers.
Figure 15 looks quite like a hockey stick to me. Where did the MWP go?
Of course they clearly did not use Leif’s reconstruction (the GSN curve).
And the other thing coming on my mind is how reliable the 10Be proxy might be after the era of atomic bomb tests.
Anybody remembers, Solar Max came down earlier than expected because solar activity was stronger than expected
Ps the lunar regolith should help quite a lot in reconstructing solar activity for a few billion years
Typo alert: should read “highest in the last 12000 years”, not 1200.
Looking at the graph, did you mean to say 12,000?
Sorry, you were referring to figure 15. First comment of mine withdrawn.
It’s a better correlation than CO2. As a mater of fact the Moon’s orbit has a better correlation than CO2.
Wow
Even the sun responds to increasing CO2 on earth! Is it ‘teleconnections’ again?
The devil gas has a lot to answer for.
/sarc
My view is that we should be cautious about 10Be and 14C is accurate indicators of solar activity amplitudes over the longer term (500 years or more). However, the periodicity does seem to be a reliable indicator according to the observational record. It fits well with the hindcast created using our solar-planetary theory too.
Proponents of the dynamo only theory of solar activity changes don’t seem to have come up with any model which can be compared to these proxy records.
omnologos says:
September 14, 2012 at 12:44 am
Ps the lunar regolith should help quite a lot in reconstructing solar activity for a few billion years
Interesting comment, could you explain further please.
Most interesting – I shall read this one over the weekend, as 88 pages is a little much for reading over breakfast. It’s a pity we’ve only had radio for a century or so, as a radio enthusiast I’d love to know more about what our ionosphere does under different solar conditions, if the last century has been untypically active the next few should be interestingly different (and, one suspects, quieter, apart from all the human pollution of the EM spectrum).
Another grammar pedant’s point (not sure whether it’s yours or theirs): phenomena is plural, phenomenon is singular.
Latimer Alder says:
September 14, 2012 at 12:50 am
Wow
Even the sun responds to increasing CO2 on earth! Is it ‘teleconnections’ again?
The devil gas has a lot to answer for.
/sarc
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yep, and so too do the outer planets, with their warmings.
Gosh: that fossil-oil CO2 really does get around!
ConfusedPhoton says:
September 14, 2012 at 12:24 am
No doubt Leif will tell us it is all wrong and link to his papers
Yes, for several reasons.
Some repeated several times.
Leif’s work is very good.
A solar cycle lost in 1793–1800:
Early sunspot observations resolve the old mystery
http://www.leif.org/EOS/Lost%20Cycle%205.pdf
I was under the impression that C14 has been heavily affected by the nuclear age because it is difficult to know how much of the C14 is from cosmic and how much man-made sources of radiation. So, before even reading I searched for the section on nuclear testing and how this error was accommodated. E.g. it may have said “man-made levels are negligible particularly now nuclear testing has stopped”.
When did this grand maximum end?
I’d like to see what the graph looks like when extended backwards through the Younger Dryas ie back further than the Holocene. That might shed light on the hockey-stickish look to the graph.
IPCC use three hockey stick curves on page 3 of their Summary for Policymakers, all taken from ice core records – CO2, methane and nitrous oxide. But I strongly suspect these have not been adequately corrected for effects of slow compression of the firn over recent centuries and rapid decompression of the ice core on extraction – just as Jaworowsky and Segalstad claim. So my immediate reaction is to suspect the HS-look – as by the same term, I suspect the ice hockey sticks thrust in my face in the IPCC SfP.
It would be nice to believe we’ve had exceptional solar activity. But recent warmth appears to have been less than MWP warmth, which in turn appears to have been less than Roman WP warmth, which was less than the one before that… according to these ice core records. Unfortunately I did not note the proxy or proxies used for that study – but at least there is no significant hockey stick when put in context.
I’m sorry this article is highly misleading and is leading people to make comments which are ill-informed, without reading the following section the article about the quality of the reconstruction (not the quality of work I hasten to add which looks good) it is impossible to make an informed comment about the importance of this maximum.
It is quite literally a hockey stick, one the author has clearly signal, but one which for reasons I do not understand have not been flagged here.
3.2.4 The Suess effect and nuclear bomb tests
Unfortunately, cosmogenic 14C data cannot be easily used for the last century, primarily because of the extensive burning of fossil fuels. Since fossil fuels do not contain 14C, the produced CO2 dilutes the atmospheric 14CO2 concentration with respect to the pre-industrial epoch. Therefore, the measured Δ14C cannot be straightforwardly translated into the production rate 𝑄 after the late 19th century, and a special correction for fossil fuel burning is needed. This effect, known as the Suess effect (e.g., Suess, 1955) can be up to −25h in Δ14C in 1950 (Tans et al., 1979), which is an order of magnitude larger than the amplitude of the 11-year cycle of a few per mil.Moreover, while the cosmogenic production of 14C is roughly homogeneous over the globe and time, the use of fossil fuels is highly nonuniform (e.g., de Jong and Mook, 1982) both spatially (developed countries, in the northern hemisphere) and temporarily (WorldWars, Great Depression, industrialization, etc.). This makes it very difficult to perform an absolute normalization of the radiocarbon production to the direct measurements. Sophisticated numerical models (e.g., Sabine et al., 2004; Mikaloff Fletcher et al., 2006) aim to account for the Suess effect and make good progress. However, the results obtained indicate that the determination of the Suess effect does not yet reach the accuracy required for the precise modelling and reconstruction of the 14C production for the industrial epoch. As noted by Matsumoto et al. (2004), “. . . Not all is well with the current generation of ocean carbon cycle models. At the same time, this highlights the danger in simply using the available models to represent state-of-the-art modeling without considering the credibility of each model.” Note that the atmospheric concentration of another carbon isotope 13C is partly affected by land use, which has also been modified during the last century.
Another anthropogenic activity greatly disturbing the natural variability of 14C is related to the
atmospheric nuclear bomb tests actively performed in the 1960s. For example, the radiocarbon concentration nearly doubled in the early 1960s in the northern hemisphere after nuclear tests performed by the USSR and the USA in 1961 (Damon et al., 1978). On one hand, such sources of momentary spot injections of radioactive tracers (including 14C) provide a good opportunity to verify and calibrate the exchange parameters for different carbon -cycle reservoirs and circulation models (e.g., Bard et al., 1987; Sweeney et al., 2007). Thus, the present-day carbon cycle is more or-less known. On the other hand, the extensive additional production of isotopes during nuclear tests makes it hardly possible to use the 14C as a proxy for solar activity after the 1950s (Joos, 1994).
These anthropogenic effects do not allow one to make a straightforward link between preindustrial data and direct experiments performed during more recent decades. Therefore, the question of the absolute normalization of 14C model is still open (see, e.g., the discussion in Solanki et al., 2004, 2005; Muscheler et al., 2005).
Living Reviews in Solar Physics
http://www.livingreviews.org/lrsp-2008-3
32 Ilya G. Usoskin
Sorry in my rush to get this key information to you I said: “It is quite literally a hockey stick”. What I meant is its gluing two very different sets of data together – I didn’t mean that its a false upswing.
Skeptic’s view:
The cosmic rays count is impacted by the Earth’s magnetic field oscillations to the extent which could be equal or greater (by an order of magnitude) than that of the changes in the Heliospheric magnetic field. Scientists (NASA-JPL) only now trying to understand impact of Earth’s magnetic field changes.
At this point in time it is difficult to resolve differences which can be attributed to either of two quoting Dr. Jean Dickey of NASA’s Jet Propulsion Laboratory, Pasadena:
One possibility is the movements of Earth’s core (where Earth’s magnetic field originates) might disturb Earth’s magnetic shielding of charged-particle (i.e., cosmic ray) fluxes . ……
My small but pioneering effort in that direction is shown here:
http://www.vukcevic.talktalk.net/TMC.htm