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Eleven-year solar cycles over the last millennium revealed by radiocarbon in tree rings

Nature Geoscience volume 14, pages 10–15 (2021)Cite this article

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Abstract

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.

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Fig. 1: From annual Δ14C records to solar modulation.
Fig. 2: Two new event candidates detected in the 1,000-yr record.
Fig. 3: Frequency analysis of band-pass filtered Δ14C records.
Fig. 4: Amplitude and period distributions.

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Data availability

The excel data that support the findings of this study are available in PANGEA at https://doi.org/10.1594/PANGAEA.921808.Source data are provided with this paper.

References

  1. Lal, D. & Peters, B. in Kosmische Strahlung II: Handbuch der Physik 551–612 (Springer, 1967).

  2. Herbst, K., Muscheler, R. & Heber, B. The new local interstellar spectra and their influence on the production rates of the cosmogenic radionuclides 10Be and 14C. J. Geophys. Res. Space Phys. 122, 23–34 (2017).

    Article  Google Scholar 

  3. Kovaltsov, G. A., Mishev, A. & Usoskin, I. G. A new model of cosmogenic production of radiocarbon 14C in the atmosphere. Earth Planet. Sci. Lett. 337, 114–120 (2012).

    Article  Google Scholar 

  4. Snowball, I. & Muscheler, R. Palaeomagnetic intensity data: an Achilles heel of solar activity reconstructions. Holocene 17, 851–859 (2007).

    Article  Google Scholar 

  5. Bard, E., Raisbeck, G., Yiou, F. & Jouzel, J. Solar irradiance during the last 1200 years based on cosmogenic nuclides. Tellus B 52, 985–992 (2000).

    Article  Google Scholar 

  6. Muscheler, R. et al. Solar activity during the last 1000 yr inferred from radionuclide records. Quat. Sci. Rev. 26, 82–97 (2007).

    Article  Google Scholar 

  7. Usoskin, I. G. A history of solar activity over millennia. Living Rev. Sol. Phys. 10, 1 (2013).

    Article  Google Scholar 

  8. Beer, J., Vonmoos, M. & Muscheler, R. Solar variability over the past several millennia. Space Sci. Rev. 125, 67–79 (2006).

    Article  Google Scholar 

  9. Steinhilber, F., Beer, J. & Frohlich, C. Total solar irradiance during the Holocene. Geophys. Res. Lett. 36, L19704 (2009).

  10. Miyake, F., Nagaya, K., Masuda, K. & Nakamura, T. A signature of cosmic-ray increase in ad 774–775 from tree rings in Japan. Nature 486, 240–242 (2012).

    Article  Google Scholar 

  11. Miyake, F., Masuda, K. & Nakamura, T. Another rapid event in the carbon-14 content of tree rings. Nat. Commun. 4, 1748 (2013).

    Article  Google Scholar 

  12. Park, J., Southon, J., Fahrni, S., Creasman, P. P. & Mewaldt, R. Relationship between solar acitvity and Δ14C in AD 775, AD 994, and 660 BC. Radiocarbon 59, 1147–1156 (2017).

    Article  Google Scholar 

  13. Usoskin, I. G. et al. The AD775 cosmic event revisited: the Sun is to blame. Astron. Astrophys. 552, L3 (2013).

  14. Mekhaldi, F. et al. Multiradionuclide evidence for the solar origin of the cosmic-ray events of AD 774/5 and 993/4. Nat. Commun. 6, 8611 (2015).

    Article  Google Scholar 

  15. Dyer, C., Hands, A., Ryden, K. & Lei, F. Extreme atmospheric radiation environments and single event effects. IEEE Trans. Nucl. Sci. 65, 432–438 (2018).

    Article  Google Scholar 

  16. Bayliss, A. et al. Informing conservation: towards 14C wiggle-matching of short tree-ring sequences from medieval buildings in England. Radiocarbon 59, 985–1007 (2017).

    Article  Google Scholar 

  17. Stuiver, M. & Braziunas, T. F. Sun, ocean, climate and atmospheric 14CO2: an evaluation of causal and spectral relationships. Holocene 3, 289–305 (1993).

    Article  Google Scholar 

  18. Eastoe, C. J., Tucek, C. S. & Touchan, R. Δ14C and δ13C in annual tree-ring samples from sequoiadendron giganteum, AD 998–1510: solar cycles and climate. Radiocarbon 61, 661–680 (2019).

    Article  Google Scholar 

  19. Hong, W. et al. Calibration curve from AD 1250 to AD 1650 by measurements of tree-rings grown on the Korean peninsula. Nucl. Instrum. Methods Phys. Res. Sect. B 294, 435–439 (2013).

    Article  Google Scholar 

  20. Moriya, T. et al. A study of variation of the 11-yr solar cycle before the onset of the Spoerer minimum based on annually measured 14C content in tree rings. Radiocarbon 61, 1749–1754 (2019).

    Article  Google Scholar 

  21. Menjo, H. et al. Possibility of the detection of past supernova explosion by radiocarbon measurement. In Proc. 29th International Cosmic Ray Conference (eds Sripathi Acharya, B. et al.) 357–360 (TIFR, 2005).

  22. Miyahara, H. et al. Variation of solar activity from the Spoerer to the Maunder minima indicated by radiocarbon content in tree-rings. Adv. Space Res 40, 1060–1063 (2007).

    Article  Google Scholar 

  23. Miyahara, H. et al. Transition of solar cycle length in association with the occurrence of grand solar minima indicated by radiocarbon content in tree-rings. Quat. Geochronol. 3, 208–212 (2008).

    Article  Google Scholar 

  24. Fogtmann-Schulz, A. et al. Variations in solar activity across the Sporer minimum based on radiocarbon in Danish oak. Geophys. Res. Lett. 46, 8617–8623 (2019).

    Article  Google Scholar 

  25. Kudsk, S. G. K. et al. New single-year radiocarbon measurements based on Danish oak covering the periods AD 692–790 and 966–1057. Radiocarbon 62, 969–987 (2019).

  26. Usoskin, I. G. et al. Revisited reference solar proton event of 23 February 1956: assessment of the cosmogenic‐isotope method sensitivity to extreme solar events. J. Geophys. Res. Space Physics 125, e2020JA027921 (2020).

  27. Synal, H. A. & Wacker, L. AMS measurement technique after 30 years: possibilities and limitations of low energy systems. Nucl. Instrum. Methods Phys. Res. Sect. B 268, 701–707 (2010).

    Article  Google Scholar 

  28. Stuiver, M. Solar variability and climatic-change during the current millennium. Nature 286, 868–871 (1980).

    Article  Google Scholar 

  29. Stuiver, M. & Quay, P. D. Atmospheric 14C changes resulting from fossil-fuel CO2 release and cosmic-ray flux variability. Earth Planet. Sci. Lett. 53, 349–362 (1981).

    Article  Google Scholar 

  30. Keeling, C. D. The Suess effect: 13C-14C interrelations. Environ. Int. 2, 229–300 (1979).

    Article  Google Scholar 

  31. Gleeson, L. J. & Axford, W. I. Solar modulation of galactic cosmic rays. Astrophys. J. 154, 1011–1026 (1968).

    Article  Google Scholar 

  32. Sunspot Index and Long-term Solar Observations (SILSO WDC, 2019); http://www.sidc.be/silso/

  33. Eddy, J. A. The Maunder minimum. Science 192, 1189–1202 (1976).

    Article  Google Scholar 

  34. Usoskin, I. G., Solanki, S. K. & Kovaltsov, G. A. Grand minima of solar activity during the last millennia. Proc. Int. Astron. Union 286, 372–382 (2012).

    Google Scholar 

  35. Brönnimann, S. et al. Last phase of the little ice age forced by volcanic eruptions. Nat. Geosci. 12, 650–656 (2019).

    Article  Google Scholar 

  36. Goosse, H., JoelGuiot, Mann, M. E., Dubinkina, S. & Sallaz-Damaz, Y. The medieval climate anomaly in Europe: comparison of the summer and annual mean signals in two reconstructions and in simulations with data assimilation. Glob. Planet. Change 84–85, 35–47 (2012).

    Article  Google Scholar 

  37. Ganopolski, A. & Rahmstorf, S. Abrupt glacial climate changes due to stochastic resonance. Phys. Rev. Lett. 88, 038501 (2002).

    Article  Google Scholar 

  38. National Research Council Severe Space Weather Events—Understanding Societal and Economic Impacts: A Workshop Report: Extended Summary (National Academies, 2009).

  39. Schrimpf, R. D. & Fleetwood, D. M. Radiation Effects and Soft Errors in Integrated Circuits and Electronic Devices (World Scientific, 2004).

  40. Cuny, H. E. et al. Woody biomass production lags stem-girth increase by over one month in coniferous forests. Nat. Plants 1, 15160 (2015).

  41. Stuiver, M., Kromer, B., Becker, B. & Ferguson, C. W. Radiocarbon age calibration back to 13,300 Years BP and the 14C age matching of the german oak and united-states bristlecone-pine chronologies. Radiocarbon 28, 969–979 (1986).

    Article  Google Scholar 

  42. Reimer, P. J. et al. IntCal13 and Marine13 radiocarbon age calibration curves 0–50,000 years cal BP. Radiocarbon 55, 1869–1887 (2013).

  43. Sookdeo, A. et al. Quality dating: a well-defined protocol implemented at ETH for high-precision 14C dates tested on late glacial wood. Radiocarbon https://doi.org/10.1017/RDC.2019.132 (2020).

  44. Němec, M., Wacker, L., Hajdas, I. & Gäggeler, H. Alternative methods for cellulose preparation for AMS measurement. Radiocarbon 52, 1358–1370 (2016).

    Article  Google Scholar 

  45. Welte, C. et al. Towards the limits: analysis of microscale 14C samples using EA-AMS. Nucl. Instrum. Methods Phys. Res. Sect. B 437, 66–74 (2018).

    Article  Google Scholar 

  46. Wacker, L., Nemec, M. & Bourquin, J. A revolutionary graphitisation system: fully automated, compact and simple. Nucl. Instrum. Methods Phys. Res. Sect. B 268, 931–934 (2010).

    Article  Google Scholar 

  47. Wacker, L., Christl, M. & Synal, H. A. Bats: a new tool for AMS data reduction. Nucl. Instrum. Methods Phys. Res. Sect. B 268, 976–979 (2010).

    Article  Google Scholar 

  48. Reimer, P. J., Brown, T. A. & Reimer, W. R. Discussion: reporting and calibration of post-bomb C data. Radiocarbon 46, 1299–1304 (2004).

    Article  Google Scholar 

  49. Stuiver, M. & Becker, B. High-precision decadal calibration of the radiocarbon time scale, AD 1950–6000 BC. Radiocarbon 35, 35–65 (2016).

    Article  Google Scholar 

  50. Stuiver, M. A note on single-year calibration of the radiocarbon time scale, AD 1510–1954. Radiocarbon 35, 67–72 (1993).

  51. Stuiver, M., Braziunas, T. F., Becker, B. & Kromer, B. Climatic, solar, oceanic, and geomagnetic influences on late-glacial and holocene atmospheric 14C/12C change. Quat. Res. 35, 1–24 (1991).

    Article  Google Scholar 

  52. Stuiver, M. & Braziunas, T. F. Anthropogenic and solar components of hemispheric 14C. Geophys. Res. Lett. 25, 329–332 (1998).

    Article  Google Scholar 

  53. Manning, S. W. et al. Fluctuating radiocarbon offsets observed in the southern Levant and implications for archaeological chronology debates. Proc. Natl Acad. Sci. USA 115, 6141–6146 (2018).

  54. Mursula, K., Usoskin, I. G. & Kovaltsov, G. A. Reconstructing the long-term cosmic ray intensity: linear relations do not work. Ann. Geophys. 21, 863–867 (2003).

    Article  Google Scholar 

  55. Owens, M. J., Usoskin, I. & Lockwood, M. Heliospheric modulation of galactic cosmic rays during grand solar minima: past and future variations. Geophys. Res. Lett. 39, L19102 (2012).

  56. Guttler, D. et al. Rapid increase in cosmogenic 14C in AD 775 measured in New Zealand kauri trees indicates short-lived increase in 14C production spanning both hemispheres. Earth Planet. Sci. Lett. 411, 290–297 (2015).

    Article  Google Scholar 

  57. Savitzky, A. & Golay, M. J. E. Smoothing and differentiation of data by simplified least squares procedures. Anal. Chem. 36, 1627–1639 (1964).

    Article  Google Scholar 

  58. Boden, T. A. & Andres, R. J. Global, Regional, and National Fossil-Fuel CO2 Emissions (Carbon Dioxide Information Analysis Center, 2016); https://doi.org/10.3334/CDIAC/00001_V2016

  59. Usoskin, I. G., Alanko-Huotari, K., Kovaltsov, G. A. & Mursula, K. Heliospheric modulation of cosmic rays: monthly reconstruction for 1951-2004. J. Geophys. Res. 110, A12108 (2005).

  60. Hellio, G. & Gillet, N. Time-correlation-based regression of the geomagnetic field from archeological and sediment records. Geophys. J. Int. 214, 1585–1607 (2018).

    Article  Google Scholar 

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Acknowledgements

We thank A. Arnold and R. Howard of the Nottingham Tree Ring Dating Laboratory for their careful dissection of the samples of English oak, and S. Arnold for her careful sample preparations. S. St George and the University of Minnesota are acknowledged for carefully reviewing the manuscript and for their positive and constructive comments, which considerably improved this study. The Laboratory of Ion Beam Physics is partially funded by its consortium partners PSI, EAWAG and EMPA. N.B. is funded by the Swiss National Science Foundation (SNSF grant number SNF 197137). I.U. acknowledges support from the Academy of Finland (project number 321882 ESPERA).

Author information

Author notes

  1. Florian Adolphi

    Present address: Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany

Authors and Affiliations

  1. Laboratory of Ion Beam Physics, ETHZ, Zurich, Switzerland

    Nicolas Brehm, Marcus Christl, Hans-Arno Synal, Silvia Bollhalder & Lukas Wacker

  2. Historic England, London, UK

    Alex Bayliss & Cathy Tyers

  3. Department of Geology, Lund University, Lund, Sweden

    Florian Adolphi & Raimund Muscheler

  4. Climate and Environmental Physics, University of Bern, Bern, Switzerland

    Florian Adolphi

  5. Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland

    Florian Adolphi

  6. Eawag, Dübendorf, Switzerland

    Jürg Beer

  7. Institute of Environmental Physics, Heidelberg University, Heidelberg, Germany

    Bernd Kromer

  8. Max-Planck-Institut für Sonnensystemforschung, Göttingen, Germany

    Sami K. Solanki

  9. School of Space Research, Kyung Hee University, Yongin, Republic of Korea

    Sami K. Solanki

  10. Space Physics and Astronomy Research Unit, University of Oulu, Oulu, Finland

    Ilya Usoskin

  11. Sodankylä Geophysical Observatory, University of Oulu, Oulu, Finland

    Ilya Usoskin

  12. Underwater Archaeology and Dendroarchaeology, Office for Urbanism, Zurich, Switzerland

    Niels Bleicher

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Contributions

L.W., M.C. and N. Brehm designed the study with input from H.-A.S., A.B., C.T. and N. Bleicher. A.B., C.T. and N. Bleicher supplied the annually resolved tree ring samples and are responsible for the documentation of the dendrochronology. Radiocarbon measurements and analyses were performed by S.B., N. Brehm and L.W. The modelling and interpretation of the 14C data to extract the solar modulation was done by N. Brehm, M.C. and L.W. with input from F.A., J.B., B.K., R.M., S.K.S., I.U. and H.-A.S. N. Brehm, M.C. and L.W. wrote the manuscript with input from all co-authors.

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Correspondence to Nicolas Brehm, Marcus Christl or Lukas Wacker.

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Extended data

Extended Data Fig 1 Comparison of IntCal13 raw data with ETH data.

Annually resolved radiocarbon measurements as Δ14C (red, left axis) compared with the raw data of IntCal13 (blue) at the top. The 14C age offsets in years (QL minus ETH, right axis) of the two datasets (green dots) with a moving average (green line, Savitzky-Golay filter) over time are shown on the bottom (8 years correspond to an offset of 1‰ in Δ14C). The error bars indicate two sigma errors.

Extended Data Fig 2 Comparison of Mediterranean Jordanian Juniper data with ETH data.

The published radiocarbon measurements on Jordanian juniper (JJ) performed in Oxford (OxA)53 and Arizona (AA)53 are compared with the raw values of IntCal13 (blue curve) and the new annual ETH measurements on British and Swiss oak samples (green) for selected time intervals (between dotted blue lines). The radiocarbon offsets of JJ from IntCal (as already observed by Manning et al.53) are substantially larger in some intervals and less consistant than the offsets of JJ to the ETH data. The error bars indicate two sigma errors.

Extended Data Fig. 3 Depiction of our in-house multi carbon box model.

The fluxes are given in Gt/yr and the 12C box contents are given in Gt of carbon.

Extended Data Fig. 4 Simulation of the Suess effect.

Simulated decrease of ∆14C of the northern (green) and southern (red) hemisphere compared with measured ETH 14C data (blue) and southern hemisphere Intcal13 data42(orange) using a constant 14C production rate of 6.6 kg/yr and using the global emission data of Boden et al.58 (black). The error bars indicate two sigma errors.

Extended Data Fig. 5 Direct comparison of reconstructed solar modulation parameter with sunspots.

Sunspots32 (black) with the solar modulation parameter calculated from ETH (blue) and QL (orange) data. The blue band indicates the estimated 2 sigma errors of the reconstructed solar modulation parameter of the ETH data by using 1000 Monte Carlo simulations.

Extended Data Fig. 6 Reconstruction of additionally produced 14C during SEP events.

(a) Different Monte Carlo simulations with the distribution in simulated ∆14C increases (b) and additional production (c) of the different datasets.

Extended Data Fig. 7 Direct peak to peak comparison with Sunspots.

Comparison of 6–18 yr band passed peak to peak distances of ETH (a/b blue) and QL (c/d orange) with band passed peak to peak distances of sunspots (black). In a/c the histogram of all distances is shown and in b/d only peak distances with a mean amplitude of more than 1.2 ‰ are shown.

Extended Data Fig. 8 Random data generation with increasing sinusoidal amplitude.

The blue histograms show amplitude, period, and point to point distance distributions (∆∆14C) after 6–18 yr bandpass filtering of random data containing an artificial periodic 10.4 yr signal with different amplitudes. From top to bottom the amplitude of the periodic signal is increased from 0‰ up to 3‰. The artificial data errors were adjusted such that the width of the ∆∆14C distribution is the same as the ∆∆14C distribution of our measured samples with a width of 2.03‰.

Supplementary information

Supplementary Information

Supplementary Discussion, Figs. 1–3 and Tables 1–17.

Source data

Source Data Fig. 1

Numerical data for Fig. 1.

Source Data Fig. 2

Numerical data for Fig. 2.

Source Data Extended Data Fig. 1

Numerical data for Extended Data Fig. 1.

Source Data Extended Data Fig. 2

Numerical data for Extended Data Fig. 2.

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Brehm, N., Bayliss, A., Christl, M. et al. Eleven-year solar cycles over the last millennium revealed by radiocarbon in tree rings. Nat. Geosci. 14, 10–15 (2021). https://doi.org/10.1038/s41561-020-00674-0

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