# Projected decreases in future marine export production: The role of carbon fluxes through the upper ocean ecosystem

Author(s) Laufkötter, Charlotte, Vogt, M., Gruber, Nicolas, Aumont, O., Bopp, L., Doney, S.C., Dunne, J.P., Hauck, J., John, J.G., Lima, I.D., Seferian, R., Völker, C.
Publication Type Journal Items, Publication Status: Published
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Title Projected decreases in future marine export production: The role of carbon fluxes through the upper ocean ecosystem
Author(s) Laufkötter, Charlotte
Vogt, M.
Gruber, Nicolas
Aumont, O.
Bopp, L.
Doney, S.C.
Dunne, J.P.
Hauck, J.
John, J.G.
Lima, I.D.
Seferian, R.
Völker, C.
Journal or Series Title Biogeosciences Discussions
Volume Number 12
Start Page 19941
End Page 19998
ISSN 1810-6277
1810-6285
Publisher Copernicus Publ.
Publication Place Göttingen
Publication Date 2015
Abstract Accurate projections of marine particle export production (EP) are crucial for predicting the response of the marine carbon cycle to climate change, yet models show a wide range in both global EP and their responses to climate change. This is, in part, due to EP being the net result of a series of processes, starting with net primary production (NPP) in the sunlit upper ocean, followed by the formation of particulate organic matter and the subsequent sinking and remineralization of these particles, with each of these processes responding differently to changes in environmental conditions. Here, we compare future projections in EP over the 21st century, generated by four marine ecosystem models under IPCC's high emission scenario RCP8.5, and determine the processes driving these changes. The models simulate small to modest decreases in global EP between −1 and −12 %. Models differ greatly with regard to the drivers causing these changes. Among them, the formation of particles is the most uncertain process with models not agreeing on either magnitude or the direction of change. The removal of the sinking particles by remineralization is simulated to increase in the low and intermediate latitudes in three models, driven by either warming-induced increases in remineralization or slower particle sinking, and show insignificant changes in the remaining model. Changes in ecosystem structure, particularly the relative role of diatoms matters as well, as diatoms produce larger and denser particles that sink faster and are partly protected from remineralization. Also this controlling factor is afflicted with high uncertainties, particularly since the models differ already substantially with regard to both the initial (present-day) distribution of diatoms (between 11–94 % in the Southern Ocean) and the diatom contribution to particle formation (0.6–3.8 times lower/higher than their contribution to biomass). As a consequence, changes in diatom concentration are a strong driver for EP changes in some models but of low significance in others. Observational and experimental constraints on ecosystem structure and how the fixed carbon is routed through the ecosystem to produce export production are urgently needed in order to improve current generation ecosystem models and their ability to project future changes.
DOI 10.5194/bgd-12-19941-2015
Additional Notes Published online 14 December 2015
Document Type Article
Publication Status Published
Language English
Assigned Organisational Unit(s) 03731
Organisational Unit(s)
NEBIS System Number 010153508
Source Database ID FORM-1450361072
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@article{Lfkttr2015,
author = "Laufk{\"{o}}tter, Charlotte and Vogt, M. and Gruber, Nicolas and Aumont, O. and Bopp, L. and Doney, S.C. and Dunne, J.P. and Hauck, J. and John, J.G. and Lima, I.D. and Seferian, R. and V{\"{o}}lker, C.",
title = "{P}rojected decreases in future marine export production: {T}he role of carbon fluxes through the upper ocean ecosystem",
journal = "Biogeosciences Discussions",
year = 2015,
volume = "12",
pages = "19941--19998",
}


E-Citations record created: Thu, 17 Dec 2015, 14:04:36 CET