Temporal Fluctuations of Atmospheric 14C: Causal Factors and Implications

Damon, Paul E.; Lerman, J. C.; Long, Austin

doi:10.1146/annurev.ea.06.050178.002325

Cited by 205 publications

(98 citation statements)

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“…This assumption is well validated for the the Holocene (Damon et al 1978;Stuiver et al 1991) as there is no evidence of considerable oceanic change or other natural variability of the carbon cycle (Gerber et al 2002), and accordingly all variations of Δ 14 C predominantly reflect the production rate. This is supported by the strong similarity of the fluctuations of the 10 Be data in polar ice cores (Sect.…”

Section: Transport and Depositionmentioning

confidence: 77%

A history of solar activity over millennia

Usoskin

2017

Living Rev Sol Phys

391

241

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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 proxies, such as the cosmogenic isotopes 14 C and 10 Be 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

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Section: Transport and Depositionmentioning

confidence: 77%

A history of solar activity over millennia

Usoskin

2017

Living Rev Sol Phys

391

241

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“…Ice cores, and tree ring and other proxy records (e.g. lake macrofossil, marine foraminifera, coral and speleothem records), additionally reveal decadal to millennial variations associated with climate and carbon cycle variability, and, for 14 C, changes in solar activity and the geomagnetic field (Damon et al, 1978).…”

Section: Introductionmentioning

confidence: 98%

Compiled records of carbon isotopes in atmospheric CO<sub>2</sub> for historical simulations in CMIP6

et al. 2017

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Abstract. The isotopic composition of carbon ( 14 C and δ 13 C) in atmospheric CO 2 and in oceanic and terrestrial carbon reservoirs is influenced by anthropogenic emissions and by natural carbon exchanges, which can respond to and drive changes in climate. Simulations of 14 C and 13 C in the ocean and terrestrial components of Earth system models (ESMs) present opportunities for model evaluation and for investigation of carbon cycling, including anthropogenic CO 2 emissions and uptake. The use of carbon isotopes in novel evaluation of the ESMs' component ocean and terrestrial biosphere models and in new analyses of historical changes may improve predictions of future changes in the carbon cycle and climate system. We compile existing data to produce records of 14 C and δ 13 C in atmospheric CO 2 for the historical period 1850-2015. The primary motivation for this compilation is to provide the atmospheric boundary condition for historical simulations in the Coupled Model Intercomparison Project 6 (CMIP6) for models simulating carbon isotopes in the ocean or terrestrial biosphere. The data may also be useful for other carbon cycle modelling activities.

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“…It is concluded that the observed higher frequency wiggles in atmospheric "C/12C ratios occurring with time scales of about two hundred years and of 1 to 2 percent in magnitude (de Vries, 1958; Suess, 1970a,b;1979;Damon, Lerman, and Long, 1978), are largely due to solar activity dependent modulation of the galactic cosmic ray flux by solar plasma. These variations override a slowly varying sinusoidal change of about 10 percent in magnitude during the last approximately 8000 years, which is believed to be primarily due to changes in the geomagnetic field.…”

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confidence: 99%

Solar Modulation Effects in Terrestrial Production of Carbon-14

Castagnoli¹,

1980

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ABSTRACT. This paper is concerned with the expected deviations in the production rate of natural 14C on the earth due to changes in solar activity. We review the published estimates of the global production rates of 14C due to galactic and solar cosmic ray particles, and present new estimates of the expected secular variations in 14C production, taking into account the latest information available on galactic cosmic ray modulation and long-term variations in solar activity.Estimated secular variations are related to data on atmospheric 14Cf 12C ratios based on tree rings. It is concluded that the observed higher frequency wiggles in atmospheric "C/12C ratios occurring with time scales of about two hundred years and of 1 to 2 percent in magnitude (de Vries, 1958; Suess, 1970a,b;1979;Damon, Lerman, and Long, 1978), are largely due to solar activity dependent modulation of the galactic cosmic ray flux by solar plasma. These variations override a slowly varying sinusoidal change of about 10 percent in magnitude during the last approximately 8000 years, which is believed to be primarily due to changes in the geomagnetic field. The high frequency modulation effect in 14C production is substantial, about 20 percent, which, considering the response function of the atmosphere (cf Houtermans, Suess, and Oeschger, 1973), is adequate to explain the observed 14C wiggles (also named Suess wiggles or de Vries oscillations) if in the past, periods of large modulation effects and also periods of weak modulation persisted, ie, the sun remained both active and inactive over long periods of time, of the order of several decades to centuries. The pioneering investigations of Eddy (1976; 1977) of the ancient records of solar activity make it plausible that the 14C wiggles in the ancient 14C/12C ratios are primarily due to modulation of galactic cosmic ray flux by a varying sun. Thus, the 14C wiggles are good indicators of solar activity in the past.We also present revised estimates of the production rates of 14C on the earth due to solar flare accelerated cosmic rays and limits of direct accretion of 14C on the earth.

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Temporal Fluctuations of Atmospheric 14C: Causal Factors and Implications

Cited by 205 publications

References 0 publications

A history of solar activity over millennia

A history of solar activity over millennia

Compiled records of carbon isotopes in atmospheric CO<sub>2</sub> for historical simulations in CMIP6

Solar Modulation Effects in Terrestrial Production of Carbon-14

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Temporal Fluctuations of Atmospheric 14C: Causal Factors and Implications

Cited by 205 publications

References 0 publications

A history of solar activity over millennia

A history of solar activity over millennia

Compiled records of carbon isotopes in atmospheric CO&lt;sub&gt;2&lt;/sub&gt; for historical simulations in CMIP6

Solar Modulation Effects in Terrestrial Production of Carbon-14

Contact Info

Product

Resources

About

Compiled records of carbon isotopes in atmospheric CO<sub>2</sub> for historical simulations in CMIP6