# Oceanic N2O emissions in the 21st century using the IPSL Earth System Model

Author(s) Martinez-Rey, J., Bopp, Laurent, Gehlen, Marion, Tagliabue, Alessandro, Gruber, Nicolas
Publication Type Journal Items, Publication Status: Published
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Title Oceanic N2O emissions in the 21st century using the IPSL Earth System Model
Author(s) Martinez-Rey, J.
Bopp, Laurent
Gehlen, Marion
Tagliabue, Alessandro
Gruber, Nicolas
Journal or Series Title Biogeosciences
Volume Number 12
Start Page 4133
End Page 4148
ISSN 1726-4170
1726-4189
Publisher Copernicus GmbH
Publication Place Goettingen
Publication Date 2015
Abstract The ocean is a substantial source of nitrous oxide (N2O) to the atmosphere, but little is known about how this flux might change in the future. Here, we investigate the potential evolution of marine N2O emissions in the 21st century in response to anthropogenic climate change using the global ocean biogeochemical model NEMO-PISCES. Assuming nitrification as the dominant N2O formation pathway, we implemented two different parameterizations of N2O production which differ primarily under low-oxygen (O2) conditions. When forced with output from a climate model simulation run under the business-as-usual high-CO2 concentration scenario (RCP8.5), our simulations suggest a decrease of 4 to 12 % in N2O emissions from 2005 to 2100, i.e., a reduction from 4.03/3.71 to 3.54/3.56 TgN yr−1 depending on the parameterization. The emissions decrease strongly in the western basins of the Pacific and Atlantic oceans, while they tend to increase above the oxygen minimum zones (OMZs), i.e., in the eastern tropical Pacific and in the northern Indian Ocean. The reduction in N2O emissions is caused on the one hand by weakened nitrification as a consequence of reduced primary and export production, and on the other hand by stronger vertical stratification, which reduces the transport of N2O from the ocean interior to the ocean surface. The higher emissions over the OMZ are linked to an expansion of these zones under global warming, which leads to increased N2O production, associated primarily with denitrification. While there are many uncertainties in the relative contribution and changes in the N2O production pathways, the increasing storage seems unequivocal and determines largely the decrease in N2O emissions in the future. From the perspective of a global climate system, the averaged feedback strength associated with the projected decrease in oceanic N2O emissions amounts to around −0.009 W m−2 K−1, which is comparable to the potential increase from terrestrial N2O sources. However, the assessment for a potential balance between the terrestrial and marine feedbacks calls for an improved representation of N2O production terms in fully coupled next-generation Earth system models.
DOI 10.5194/bg-12-4133-2015
Additional Notes Published online 13 July 2015
Document Type Article
Publication Status Published
Language English
Assigned Organisational Unit(s) 03731
Organisational Unit(s)
NEBIS System Number 006289717
Source Database ID FORM-1454057943
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@article{Mrtnz2015,
author = "Martinez-Rey, J. and Bopp, Laurent and Gehlen, Marion and Tagliabue, Alessandro and Gruber, Nicolas",
title = "{O}ceanic {N}2{O} emissions in the 21st century using the {I}{P}{S}{L} {E}arth {S}ystem {M}odel",
journal = "Biogeosciences",
year = 2015,
volume = "12",
pages = "4133--4148",
}


E-Citations record created: Fri, 29 Jan 2016, 08:59:05 CET