Projecting atmospheric N2O rise until the end of the 21st century: an Earth System Model study

Nitrous Oxide (N _2 O) is a potent greenhouse gas with a centennial-scale lifetime that contributes significantly to global warming. It is emitted from natural and anthropogenic sources. In nature, N _2 O is released mainly from nitrification and denitrification from the ocean and terrestrial system...

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Main Authors: M De Sisto, C Somes, A Landolfi, A H MacDougall
Format: Article
Language:English
Published: IOP Publishing 2024-01-01
Series:Environmental Research Letters
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Online Access:https://doi.org/10.1088/1748-9326/ad8c6c
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author M De Sisto
C Somes
A Landolfi
A H MacDougall
author_facet M De Sisto
C Somes
A Landolfi
A H MacDougall
author_sort M De Sisto
collection DOAJ
description Nitrous Oxide (N _2 O) is a potent greenhouse gas with a centennial-scale lifetime that contributes significantly to global warming. It is emitted from natural and anthropogenic sources. In nature, N _2 O is released mainly from nitrification and denitrification from the ocean and terrestrial systems. The use of agricultural fertilizers has significantly increased the emission of N _2 O in the past century. Here we present, to our knowledge, the first coupled ocean and terrestrial N _2 O modules within an Earth System Model. The coupled modules were used to simulate the six Shared Socioeconomic Pathways (SSPs) scenarios with available nitrogen fertilizer inputs. Our results are compared to projections of atmospheric N _2 O concentrations used for SSPs scenario experiments. Additionally, an extra set of simulations were prescribed with emulated N _2 O concentrations available as input in Shared Socioeconomic Pathways scenarios. We report four main drivers for terrestrial N _2 O uncertainties: atmospheric temperature, agricultural fertilizer input, soil denitrification and agricultural model dynamics. We project an atmospheric N _2 O concentration range from 401 to 418 ppb in six SSPs simulations with a robust lack of sensitivity to equilibrium climate sensitivity. We found a large difference between our low emission scenarios N _2 O concentrations by 2100 compared to the concentration provided for SSPs experiments. This divergence is likely explained by strong mitigation assumptions that were not accounted for in this study, which would require a substantial decrease of agricultural N _2 O emissions. The coupled model and the simulations prescribed with N _2 O concentrations showed a difference between −0.02 and 0.09 ^∘ C by 2100. Our model simulation shows a lack of sensitivity to climate mitigation efforts projecting similar N _2 O concentration in low and high mitigation scenarios, that could indicate the need of further development of agricultural model dynamics. Further improvements in Earth system models should focus on the impact of oxygen decline on N _2 O dynamics in the ocean and the representation of anaerobic soils and agricultural dynamics on land, including mitigation methods on nitrogen fertilizers.
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spelling doaj-art-c9a22c8ed1c7458182e726182c7c85ba2024-11-12T15:12:47ZengIOP PublishingEnvironmental Research Letters1748-93262024-01-01191212403610.1088/1748-9326/ad8c6cProjecting atmospheric N2O rise until the end of the 21st century: an Earth System Model studyM De Sisto0https://orcid.org/0009-0001-3478-3555C Somes1https://orcid.org/0000-0003-2635-7617A Landolfi2A H MacDougall3https://orcid.org/0000-0003-1094-6783St. Francis Xavier University , Antigonish, NS, Canada; Faculty of Engineering and Applied Science, Memorial University of Newfoundland , St. John’s, NL, CanadaGEOMAR Helmholtz Centre for Ocean Research Kiel , Kiel, GermanyGEOMAR Helmholtz Centre for Ocean Research Kiel , Kiel, GermanySt. Francis Xavier University , Antigonish, NS, CanadaNitrous Oxide (N _2 O) is a potent greenhouse gas with a centennial-scale lifetime that contributes significantly to global warming. It is emitted from natural and anthropogenic sources. In nature, N _2 O is released mainly from nitrification and denitrification from the ocean and terrestrial systems. The use of agricultural fertilizers has significantly increased the emission of N _2 O in the past century. Here we present, to our knowledge, the first coupled ocean and terrestrial N _2 O modules within an Earth System Model. The coupled modules were used to simulate the six Shared Socioeconomic Pathways (SSPs) scenarios with available nitrogen fertilizer inputs. Our results are compared to projections of atmospheric N _2 O concentrations used for SSPs scenario experiments. Additionally, an extra set of simulations were prescribed with emulated N _2 O concentrations available as input in Shared Socioeconomic Pathways scenarios. We report four main drivers for terrestrial N _2 O uncertainties: atmospheric temperature, agricultural fertilizer input, soil denitrification and agricultural model dynamics. We project an atmospheric N _2 O concentration range from 401 to 418 ppb in six SSPs simulations with a robust lack of sensitivity to equilibrium climate sensitivity. We found a large difference between our low emission scenarios N _2 O concentrations by 2100 compared to the concentration provided for SSPs experiments. This divergence is likely explained by strong mitigation assumptions that were not accounted for in this study, which would require a substantial decrease of agricultural N _2 O emissions. The coupled model and the simulations prescribed with N _2 O concentrations showed a difference between −0.02 and 0.09 ^∘ C by 2100. Our model simulation shows a lack of sensitivity to climate mitigation efforts projecting similar N _2 O concentration in low and high mitigation scenarios, that could indicate the need of further development of agricultural model dynamics. Further improvements in Earth system models should focus on the impact of oxygen decline on N _2 O dynamics in the ocean and the representation of anaerobic soils and agricultural dynamics on land, including mitigation methods on nitrogen fertilizers.https://doi.org/10.1088/1748-9326/ad8c6cprojecting atmospheric N2O concentrationscoupled terrestrial and ocean N2O dynamicsN2O emissions
spellingShingle M De Sisto
C Somes
A Landolfi
A H MacDougall
Projecting atmospheric N2O rise until the end of the 21st century: an Earth System Model study
Environmental Research Letters
projecting atmospheric N2O concentrations
coupled terrestrial and ocean N2O dynamics
N2O emissions
title Projecting atmospheric N2O rise until the end of the 21st century: an Earth System Model study
title_full Projecting atmospheric N2O rise until the end of the 21st century: an Earth System Model study
title_fullStr Projecting atmospheric N2O rise until the end of the 21st century: an Earth System Model study
title_full_unstemmed Projecting atmospheric N2O rise until the end of the 21st century: an Earth System Model study
title_short Projecting atmospheric N2O rise until the end of the 21st century: an Earth System Model study
title_sort projecting atmospheric n2o rise until the end of the 21st century an earth system model study
topic projecting atmospheric N2O concentrations
coupled terrestrial and ocean N2O dynamics
N2O emissions
url https://doi.org/10.1088/1748-9326/ad8c6c
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AT csomes projectingatmosphericn2oriseuntiltheendofthe21stcenturyanearthsystemmodelstudy
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AT ahmacdougall projectingatmosphericn2oriseuntiltheendofthe21stcenturyanearthsystemmodelstudy