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Toward Reconciling Radiocarbon Production Rates With Carbon Cycle Changes of the Last 55,000 Years

Köhler, Peter ; Adolphi, Florian LU ; Butzin, Martin and Muscheler, Raimund LU orcid (2022) In Paleoceanography and Paleoclimatology 37(2).
Abstract

Since it is currently not understood how changes in 14C production rate (Q), and in the carbon cycle, can be combined to explain the reconstructed atmospheric Δ14C record, we discuss possible reasons for this knowledge gap. Reviewing the literature, we exclude that changes in the content of atoms in the atmosphere, which produce cosmogenic 14C after being hit by galactic cosmic rays, might be responsible for parts of the observed differences. When combining Q with carbon cycle changes, one needs to understand the changes in the atmospheric 14C inventory, which are partially counterintuitive. For example, during the Last Glacial Maximum, Δ14C was ∼400‰ higher compared with... (More)

Since it is currently not understood how changes in 14C production rate (Q), and in the carbon cycle, can be combined to explain the reconstructed atmospheric Δ14C record, we discuss possible reasons for this knowledge gap. Reviewing the literature, we exclude that changes in the content of atoms in the atmosphere, which produce cosmogenic 14C after being hit by galactic cosmic rays, might be responsible for parts of the observed differences. When combining Q with carbon cycle changes, one needs to understand the changes in the atmospheric 14C inventory, which are partially counterintuitive. For example, during the Last Glacial Maximum, Δ14C was ∼400‰ higher compared with preindustrial times, but the 14C inventory was 10% smaller. Some pronounced changes in atmospheric Δ14C do not correspond to any significant changes in the atmospheric 14C inventory, since CO2 was changing simultaneously. Using two conceptually different models (BICYCLE-SE and LSG-OGCM), we derive hypothetical Qs by forcing the models with identical atmospheric CO2 and Δ14C data. Results are compared with the most recent data-based estimates of Q derived from cosmogenic isotopes. Millennial-scale climate change connected to the bipolar seesaw is missing in the applied models, which might explain some, but probably not all, of the apparent model-data disagreement in Q. Furthermore, Q based on either data from marine sediments or ice cores contains offsets, suggesting an interpretation deficit in the current data-based approaches.

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author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
bipolar seesaw, carbon cycle, IntCal, radiocarbon
in
Paleoceanography and Paleoclimatology
volume
37
issue
2
article number
e2021PA004314
publisher
Wiley-Blackwell
external identifiers
  • scopus:85125409062
ISSN
2572-4517
DOI
10.1029/2021PA004314
language
English
LU publication?
yes
additional info
Publisher Copyright: © 2022. The Authors.
id
f152a543-0b18-4dc3-9c2a-43c13c237355
date added to LUP
2022-06-17 10:54:18
date last changed
2022-06-17 10:54:18
@article{f152a543-0b18-4dc3-9c2a-43c13c237355,
  abstract     = {{<p>Since it is currently not understood how changes in <sup>14</sup>C production rate (Q), and in the carbon cycle, can be combined to explain the reconstructed atmospheric Δ<sup>14</sup>C record, we discuss possible reasons for this knowledge gap. Reviewing the literature, we exclude that changes in the content of atoms in the atmosphere, which produce cosmogenic <sup>14</sup>C after being hit by galactic cosmic rays, might be responsible for parts of the observed differences. When combining Q with carbon cycle changes, one needs to understand the changes in the atmospheric <sup>14</sup>C inventory, which are partially counterintuitive. For example, during the Last Glacial Maximum, Δ<sup>14</sup>C was ∼400‰ higher compared with preindustrial times, but the <sup>14</sup>C inventory was 10% smaller. Some pronounced changes in atmospheric Δ<sup>14</sup>C do not correspond to any significant changes in the atmospheric <sup>14</sup>C inventory, since CO<sub>2</sub> was changing simultaneously. Using two conceptually different models (BICYCLE-SE and LSG-OGCM), we derive hypothetical Qs by forcing the models with identical atmospheric CO<sub>2</sub> and Δ<sup>14</sup>C data. Results are compared with the most recent data-based estimates of Q derived from cosmogenic isotopes. Millennial-scale climate change connected to the bipolar seesaw is missing in the applied models, which might explain some, but probably not all, of the apparent model-data disagreement in Q. Furthermore, Q based on either data from marine sediments or ice cores contains offsets, suggesting an interpretation deficit in the current data-based approaches.</p>}},
  author       = {{Köhler, Peter and Adolphi, Florian and Butzin, Martin and Muscheler, Raimund}},
  issn         = {{2572-4517}},
  keywords     = {{bipolar seesaw; carbon cycle; IntCal; radiocarbon}},
  language     = {{eng}},
  month        = {{02}},
  number       = {{2}},
  publisher    = {{Wiley-Blackwell}},
  series       = {{Paleoceanography and Paleoclimatology}},
  title        = {{Toward Reconciling Radiocarbon Production Rates With Carbon Cycle Changes of the Last 55,000 Years}},
  url          = {{http://dx.doi.org/10.1029/2021PA004314}},
  doi          = {{10.1029/2021PA004314}},
  volume       = {{37}},
  year         = {{2022}},
}