Solar activity reconstructed over a millennium

Posted: January 20, 2021 by oldbrew in Cycles, History, research
Tags: , ,

This quote from the report stood out: ‘there are long-lasting periods of strong and weak solar activity, which is also reflected in the climate on Earth.’ Worth noting as we proceed through a period of weak activity right now.
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An international team of researchers led by ETH Zurich has reconstructed solar activity back to the year 969 using measurements of radioactive carbon in tree rings, reports

Those results help scientists to better understand the dynamics of the sun and allow more precise dating of organic materials using the C14 method.

What goes on in the sun can only be observed indirectly. Sunspots, for instance, reveal the degree of solar activity—the more sunspots are visible on the surface of the sun, the more active is our central star deep inside.

Even though sunspots have been known since antiquity, they have only been documented in detail since the invention of the telescope around 400 years ago. Thanks to that, we now know that the number of spots varies in regular eleven-year cycles and that, moreover, there are long-lasting periods of strong and weak solar activity, which is also reflected in the climate on Earth.

However, how solar activity developed before the start of systematic records has so far been difficult to reconstruct.

Solar activity from tree rings

To reconstruct solar activity over a millennium with an extremely good time resolution of just one year, the researchers used tree-ring archives from England and Switzerland.

In those tree rings, whose ages can be precisely determined by counting the rings, there is a tiny fraction of radioactive carbon C14, with only one out of every 1000 billion atoms being radioactive. From the known half-life of the C14 isotope—around 5700 years—one can then deduce the concentration of radioactive carbon present in the atmosphere when the growth ring was formed.

As radioactive carbon is mainly produced by cosmic particles, which in turn are kept away from the Earth to a greater or lesser extent by the magnetic field of the sun—the more active the sun, the better it shields the Earth—it is possible to deduce solar activity from a change in the concentration of C14 in the atmosphere.

Continued here.

  1. oldbrew says:

    Re. solar cycle amplitude (from the report):

    This procedure enabled the researchers to seamlessly reconstruct solar activity from 969 to 1933. From that reconstruction they could confirm the regularity of the eleven-year cycle as well as the fact that the amplitude of that cycle (by how much the solar activity goes up and down) is also smaller during long-lasting solar minima.

  2. pochas94 says:

    Doesn’t the concentration of carbon in the atmosphere change?

  3. JB says:

    “the more sunspots are visible on the surface of the sun, the more active is our central star deep inside”

    I consider that to be shown erroneous from the work having been rendered here.

  4. tallbloke says:

    The video tells us science has only been able to trace solar activity back 400 years. But the paper has
    Steinhilber, F., Beer, J. & Frohlich, C. Total solar irradiance during the Holocene. Geophys. Res. Lett. 36, L19704 (2009).
    In it’s bibliography. They’re claiming higher resolution, enabling them to determine the amplitude of individual 11 year cycles.

    The Sun provides the principal energy input into the Earth system and solar variability represents a significant external climate forcing. Although observations of solar activity (sunspots) cover only the last about 400 years, radionuclides produced by cosmic rays and stored in tree rings or ice cores serve as proxies for solar activity extending back thousands of years. However, the presence of weather-induced noise or low temporal resolution of long, precisely dated records hampers cosmogenic nuclide-based studies of short-term solar variability such as the 11-yr Schwabe cycle. Here we present a continuous, annually resolved atmospheric 14C concentration (fractionation-corrected ratio of 14CO2 to CO2) record reconstructed from absolutely dated tree rings covering nearly all of the last millennium (AD 969–1933). The high-resolution and precision 14C record reveals the presence of the Schwabe cycle over the entire time range. The record confirms the AD 993 solar energetic particle event and reveals two new candidates (AD 1052 and AD 1279), indicating that strong solar events that might be harmful to modern electronic systems probably occur more frequently than previously thought. In addition to showing decadal-scale solar variability over the last millennium, the high-temporal-resolution record of atmospheric radiocarbon also provides a useful benchmark for making radiocarbon dating more accurate over this interval.

  5. tallbloke says:

    Message sent to corresponding author:

    Dear Marcus,

    Congratulations on your recent paper, ‘Eleven-year solar cycles over the last millennium revealed by radiocarbon in tree rings’. This is an outstanding achievement in high resolution proxy reconstruction.

    My own research group has approached this from a different angle, with some success. We use a method involving the resonant interactions of planetary orbits. The model’s specification is in the 2013 paper by Rick Salvador attached. I’ve also attached a plot showing the refined model’s output (white curve), against monthly sunspot values since 1749 (blue crosses) R^2 = 0.91

    For validation purposes, it would be very valuable if you could supply us with the values comprising your reconstruction from 969 to 1933. We could then check how well our model hindcasts deeper into the past.

    The 979-1930 portion of our 4000 year decadal values hindcast matches the 2009 Steinhilber et al 10Be based reconstruction and your higher resolution reconstruction well, on visual inspection. I hope you can accommodate my request for data so we can see how well it matches in better detail.

    Kind regards

    Roger Tattersall

  6. Paul Vaughan says:

    We looked at something similar in Be (this is C) years ago — same conclusion.
    Phase (and hence cycle length) bias integrates over mediating spatiotemporal and material channels:

  7. tallbloke says:

    There’s something seriously wrong with the time scale along the top of that plot.

  8. Paul Vaughan says:

    If you hover a mouse over the image to learn who’s responsible I don’t think you’ll be surprised.

  9. Paul Vaughan says:

    Correction: “responsible” (in quotes as it should be)

  10. oldbrew says:

    Exploring the solar wind with a new view of small sun structures
    Date: January 19, 2021
    Source: NASA/Goddard Space Flight Center

    Scientists have combined NASA data and cutting-edge image processing to gain new insight into the solar structures that create the Sun’s flow of high-speed solar wind, detailed in new research published today in The Astrophysical Journal. This first look at relatively small features, dubbed “plumelets,” could help scientists understand how and why disturbances form in the solar wind.


    NASA article:

  11. tom0mason says:

    A ‘what if’ scenario that has more credibility than the current supposition of atmospheric CO2 changing the climate.

  12. Paul Vaughan says:

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    “IT so11ending

    504.41322652433 = beat(356.533700137559,1216.12719789676)
    504.413226524325 = beat(208.886643858908,356.533700137559)
    504.413226524326 = beat(131.716392653884,178.266850068779)
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    356.533700137559 = beat(208.886643858908,504.413226524325)
    356.533700137559 = beat(178.266850068779,356.533700137559)
    356.533700137559 = beat(131.716392653884,208.886643858908)
    356.533700137558 = beat(96.1829470900285,131.716392653884)
    356.533700137556 = axial(504.413226524325,1216.12719789676)
    356.533700137557 = harmean(208.886643858908,1216.12719789676)

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    131.716392653884 = beat(104.443321929454,504.413226524325)
    131.716392653884 = beat(96.1829470900285,356.533700137559)
    131.716392653884 = beat(65.8581963269421,131.716392653884)
    131.716392653884 = axial(208.886643858908,356.533700137559)
    131.716392653884 = axial(178.266850068779,504.413226524325)
    131.716392653884 = harmean(104.443321929454,178.266850068779)
    131.716392653884 = harmean(96.1829470900285,208.886643858908)

    “I don’t need EU[]reasons”

    147.715134099352 = beat(131.716392653884,1216.12719789676)
    147.715134099352 = beat(104.443321929454,356.533700137559)
    147.715134099351 = axial(208.886643858908,504.413226524325)

    “Don’t tell me: ‘Cause’ IT hurts”

    We US-D 2 B together. Our memories:
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    “$0: Pleas!!!! Stop!! Explain UN”