Mysterious abrupt carbon-14 increase in coral contributed by a comet

Liu, Yi; Zhang, Zhaofeng; Peng, Zicheng; Ling, Ming‐Xing; Shen, Chuan‐Chou; Liu, Weiguo; Shen, Chengde; Liu, Kexin; Sun, Weixiang

doi:10.1038/srep03728

Cited by 38 publications

(49 citation statements)

References 32 publications

(51 reference statements)

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“…Hence, it is relevant to search for alternative suggestions. Liu et al (2014) pointed to an impact of a comet with Earth's atmosphere on AD 773 January 17, presumably seen in a 14 C peak in corals at that time, which was, however,…”

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confidence: 91%

“…Corresponding author: jessechapman@berkeley.edu rejected for three reasons: As mentioned in Neuhäuser & Hambaryan (2014), given the carbon cycle, 14 C would first be incorporated by trees, and later by corals, so that the sequence of events suggested by Liu et al (2014) is not possible. Both Usoskin & Kovaltsov (2014) and Melott (2014) showed that comets could not have delivered as much 14 C as needed for the AD 775 variation.…”

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confidence: 98%

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A review of East Asian reports of aurorae and comets circa AD 775

Chapman

Neuhäuser²,

Neuhäuser

et al. 2015

Astron Nachr

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Given that a strong 14C variation in AD 775 has recently been suggested to be due to the largest solar flare ever recorded in history, it is relevant to investigate whether celestial events observed around that time may have been aurorae, possibly even very strong aurorae, or otherwise related to the 14C variation (e.g. a suggested comet impact with Earth's atmosphere). We critically review several celestial observations from AD 757 to the end of the 770s, most of which were previously considered to be true, and in some cases, strong aurorae; we discuss in detail the East Asian records and their wording. We conclude that probably none among the events after AD 770 was actually an aurora, including the event in AD 776 Jan, which was misdated for AD 774 or 775; the observed white qi phenomenon that happened "above the moon" in the south-east was most probably a halo effect near the full moon - too late in any case to be related to the 14C variation in AD 774/5. There is another report of a similar (or identical) white qi phenomenon "above the moon", reported just before a comet observation and dated to AD 776 Jan; the reported comet observed by the Chinese was misdated to AD 776, but actually sighted in AD 767. Our critical review of East Asian reports of aurorae circa AD 775 shows some very likely true Chinese auroral displays observed and reported for AD 762; there were also several events prior to AD 771 that may have been aurorae but are questionable.Comment: 15 pages with 4 figure

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confidence: 91%

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confidence: 98%

A review of East Asian reports of aurorae and comets circa AD 775

Chapman

Neuhäuser²,

Neuhäuser

et al. 2015

Astron Nachr

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“…In addition, other events at 5480 BC (Miyake et al 2017a) and 660 BC (Park et al 2017) have been reported. There is also one report of excursions in corals growing in near-surface ocean (Liu et al 2014), although this is not independently reproduced. Because the amount of 14 C in the atmosphere is clearly much higher than the annual average production rate, a tremendous upsurge in production rate is needed to explain the dramatic increase in the AD 774-776 sequence (Pavlov et al 2013;Usoskin et al 2013).…”

Section: Introductionmentioning

confidence: 99%

More Rapid ¹⁴C Excursions in the Tree-Ring Record: A Record of Different Kind of Solar Activity at About 800 BC?

et al. 2018

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ABSTRACT. Two radiocarbon ( 14 C) excursions are caused by an increase of incoming cosmic rays on a short time scale found in the Late Holocene , which are widely explained as due to extreme solar proton events (SPE). In addition, a larger event has also been reported at 5480 BC (Miyake et al. 2017a), which is attributed to a special mode of a grand solar minimum, as well as another at 660 BC (Park et al. 2017). Clearly, other events must exist, but could have different causes. In order to detect more such possible events, we have identified periods when the 14 C increase rate is rapid and large in the international radiocarbon calibration (IntCal) data (Reimer et al. 2013). In this paper, we follow on from previous studies and identify a possible excursion starting at 814-813 BC, which may be connected to the beginning of a grand solar minimum associated with the beginning of the Hallstatt period, which is characterized by relatively constant 14 C ages in the period from 800-400 BC. We compare results of annual 14 C measurements from tree rings of sequoia (California) and cedar (Japan), and compare these results to other identified excursions, as well as geomagnetic data. We note that the structure of the increase from 813 BC is similar to the increase at 5480 BC, suggesting a related origin. We also assess whether there are different kinds of events that may be observed and may be consistent with different types of solar phenomena, or other explanations.

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“…This event is confirmed by annual 14 C data from a German oak tree , Russian and American tree samples (Jull et al 2014), New Zealand trees (Güttler et al 2013), etc., and corals from the Chinese Sea (Liu et al 2014) According to model simulations, the production of 14 C appears in agreement with that of 10 Be Melott and Thomas 2012;Pavlov et al 2013). Although some exotic scenarios were proposed for the event: an unidentified nearby supernova ); a gamma-ray burst (Hambaryan and Neuhäuser 2013;Pavlov et al 2013); or even a cometary impact on Earth (Liu et al 2014), it is generally accepted now that it was a signature of a (probably, consequence of) extreme SEP event Eichler and Mordecai 2012;Usoskin et al 2013;Melott and Thomas 2012;Thomas et al 2013;Cliver et al 2014). A detailed analysis performed by Mekhaldi et al (2015) not only confirmed its solar origin but also made it possible to assess, based on data from different cosmogenic isotopes, the reconstructed integral spectrum as shown in Fig.…”

Section: The Event Of 775 Ad: the Worst Case Scenario?mentioning

confidence: 99%

A history of solar activity over millennia

Usoskin

2017

Living Rev Sol Phys

359

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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Mysterious abrupt carbon-14 increase in coral contributed by a comet

Cited by 38 publications

References 32 publications

A review of East Asian reports of aurorae and comets circa AD 775

A review of East Asian reports of aurorae and comets circa AD 775

More Rapid ¹⁴C Excursions in the Tree-Ring Record: A Record of Different Kind of Solar Activity at About 800 BC?

A history of solar activity over millennia

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Mysterious abrupt carbon-14 increase in coral contributed by a comet

Cited by 38 publications

References 32 publications

A review of East Asian reports of aurorae and comets circa AD 775

A review of East Asian reports of aurorae and comets circa AD 775

More Rapid 14C Excursions in the Tree-Ring Record: A Record of Different Kind of Solar Activity at About 800 BC?

A history of solar activity over millennia

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More Rapid ¹⁴C Excursions in the Tree-Ring Record: A Record of Different Kind of Solar Activity at About 800 BC?