Climate and marine biogeochemistry during the Holocene from transient model simulations

Segschneider, Joachim; Schneider, Birgit; Khon, Vyacheslav

doi:https://doi.org/10.5194/bg-15-3243-2018

Articles | Volume 15, issue 10

https://doi.org/10.5194/bg-15-3243-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

Progress in quantifying ocean biogeochemistry – in honour...

https://doi.org/10.5194/bg-15-3243-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 15, issue 10

Research article

|

01 Jun 2018

Research article |

| 01 Jun 2018

Climate and marine biogeochemistry during the Holocene from transient model simulations

Joachim Segschneider, Birgit Schneider, and Vyacheslav Khon

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Final revised paper (published on 01 Jun 2018)
Preprint (discussion started on 04 Jan 2018)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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RC1: 'More clarification and improved explanations needed', Anonymous Referee #1, 09 Feb 2018
- AC1: 'Response to Rev#1', Joachim Segschneider, 07 Mar 2018
RC2: 'Interesting article with fascinating results comparing accelerated and normal model runs', Anonymous Referee #2, 11 Feb 2018
- AC2: 'Response to Rev#2', Joachim Segschneider, 07 Mar 2018

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (08 Mar 2018) by Christoph Heinze

AR by Joachim Segschneider on behalf of the Authors (17 Apr 2018) Author's response Manuscript

ED: Publish subject to minor revisions (review by editor) (25 Apr 2018) by Christoph Heinze

Dear Joachim Segschneider,
many thanks indeed for your revised manuscript and your detailed and throrough response. I think that you addressed the referees' points so that no further round with external reviews is needed.
There is one tiny thing, however, that I would like you to address which mainly is due to a misunderstanding. I think that referee #1 has a point in comment (7): "export production wrong metric to judge efficiency of the biological pump".
The referee is correct in that POC export production per se and atmospheric CO2 are not necessarily coupled. This would be true, if export production changes, but new production stays constant, but this ususally does not happen in the ocean. An increase in export production does not automatically imply a decrase in atmospheric pCO2 and vice versa. If one would decrease the sinking veolicty of POC, then both would go up in parallel, the POC export production and atmospheric pCO2. Biological pump efficiency as defined on how well the biological pump can keep surface nutrient (and carbon) concentrations at a low level (see Sarminto&Gruber, 2006, Ocean Biogeochemical Dynamics book, p. 111, eq. 4.1.1):
BiologicalPumpEfficiency = (Cdeep –Csurface)/Cdeep
Where C would be nutrient concentrations (or via Redfieldian changes also carbon concentrations with an offset added).
Therefore, it would be good to do two small corrections:
1. In the revised manuscript page 29 l. 26-29: Include the term pump efficiency in the discussion.
2. In the revised manuscript page 30 l. 9-10: Describe also how the pump efficiency is changing (using, e.g., global average values for nutrients and/or carbon above 200 m and below 200m depth; time slice values or indication of approximate trend suffice).
I expect that these changes can be done quickly without much additional work.
I look forward to your final version of the manuscript. Thank your for contributing to this special issue and for your patience!
Best wishes, Christoph Heinze

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AR by Joachim Segschneider on behalf of the Authors (27 Apr 2018) Author's response Manuscript

ED: Publish as is (02 May 2018) by Christoph Heinze

AR by Joachim Segschneider on behalf of the Authors (08 May 2018) Author's response

Short summary

To gain a better understanding of climate and marine biogeochemistry variations over the last 9500 years (the Holocene), we performed non-accelerated model simulations with a global coupled climate and biogeochemistry model forced by orbital parameters and atmospheric greenhouse gases. One main outcome is an increase in the volume of the eastern equatorial Pacific oxygen minimum zone, driven by a slowdown of the large-scale circulation.