04 May 2023
 | 04 May 2023
Status: this preprint is currently under review for the journal CP.

Rejuvenating the ocean: mean ocean radiocarbon, CO2 release, and radiocarbon budget closure across the last deglaciation

Luke Cameron Skinner, Francois Primeau, Aurich Jeltsch-Thömmes, Fortunat Joos, Peter Köhler, and Edouard Bard

Abstract. Radiocarbon is a tracer that provides unique insights into the ocean’s ability to sequester CO2 from the atmosphere. While spatial patterns of radiocarbon in the ocean interior can indicate the vectors and timescales for carbon transport through the ocean, estimates of the global average ocean-atmosphere radiocarbon age offset (B-Atm) place constraints on the closure of the global carbon cycle. Here, we apply a Bayesian interpolation method to compiled B-Atm data to generate global interpolated fields and mean ocean B-Atm estimates for a suite of time-slices across the last deglaciation. The compiled data and interpolations confirm a stepwise and spatially heterogeneous ‘rejuvenation’ of the ocean, suggesting that carbon was released to the atmosphere through two swings of a ‘ventilation seesaw’ operating between the North Atlantic and the Southern Ocean/North Pacific. Sensitivity tests using the Bern3D model of intermediate complexity demonstrate that a portion of the reconstructed deglacial B-Atm changes may reflect ‘phase-attenuation’ biases that are unrelated to ocean ventilation, and that could arise from independent atmospheric radiocarbon dynamics instead. However, when correcting for such biases, the sensitivity tests further demonstrate that evolving ocean-atmosphere exchange could still account for at least one third of deglacial atmospheric CO2 rise. Approximately half of the contribution to CO2 rise appears to have been associated with the Bølling-Allerød, while the rest was linked mainly to Heinrich Stadial 1 and the Younger Dryas. Our global average B-Atm estimates place further new constraints on the long-standing mystery of global radiocarbon budget closure across the last deglaciation and suggest that glacial radiocarbon production levels are likely underestimated on average by existing reconstructions.

Luke Cameron Skinner et al.

Status: open (until 07 Jul 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Luke Cameron Skinner et al.

Luke Cameron Skinner et al.


Total article views: 324 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
213 105 6 324 15 1 3
  • HTML: 213
  • PDF: 105
  • XML: 6
  • Total: 324
  • Supplement: 15
  • BibTeX: 1
  • EndNote: 3
Views and downloads (calculated since 04 May 2023)
Cumulative views and downloads (calculated since 04 May 2023)

Viewed (geographical distribution)

Total article views: 320 (including HTML, PDF, and XML) Thereof 320 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
Latest update: 03 Jun 2023
Short summary
Radiocarbon is best known as a dating tool, but it also allows us to track CO2 exchange between the ocean and atmosphere. Using decades of data and novel mapping methods, we have charted the ocean’s average radiocarbon 'age' since the last Ice Age. Combined with climate model simulations, these data quantify the ocean’s role in atmospheric CO2 rise since the last ice Age, while also revealing that Earth likely received far more cosmic radiation during the last Ice Age than hitherto believed.